4 th ventricle- anatomical and surgical perspective
TRANSCRIPT
![Page 1: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/1.jpg)
cka
SURESH BISHOKARMA MS
MCH RESIDENT NEUROSURGERY
NINAS
FOURTH VENTRICLE
ANATOMY AND SURGICAL PERSPECTIVE
The fourth ventricle is a broad tent- shaped midline cavity located
between cerebellum and brainstem
It is lined by a membrane consisting of ependyma and a double fold of pia mater which
constitutes the tela choroidea of the fourth ventricle
COMMUNICATION
It has a roof a floor and two lateral recesses
The roof superior and inferior medullary velum and cerebellar
vermis
Apex tented into cerebellum
The upper part of the roof superior cerebellar peduncles and
the superior medullary velum (thin sheet of white matter)
The inferior part of the roof Inferior medullary velum (non-
nervous tissue) Medulloblastoma origin(Youman)
ROOF
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 2: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/2.jpg)
The fourth ventricle is a broad tent- shaped midline cavity located
between cerebellum and brainstem
It is lined by a membrane consisting of ependyma and a double fold of pia mater which
constitutes the tela choroidea of the fourth ventricle
COMMUNICATION
It has a roof a floor and two lateral recesses
The roof superior and inferior medullary velum and cerebellar
vermis
Apex tented into cerebellum
The upper part of the roof superior cerebellar peduncles and
the superior medullary velum (thin sheet of white matter)
The inferior part of the roof Inferior medullary velum (non-
nervous tissue) Medulloblastoma origin(Youman)
ROOF
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 3: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/3.jpg)
COMMUNICATION
It has a roof a floor and two lateral recesses
The roof superior and inferior medullary velum and cerebellar
vermis
Apex tented into cerebellum
The upper part of the roof superior cerebellar peduncles and
the superior medullary velum (thin sheet of white matter)
The inferior part of the roof Inferior medullary velum (non-
nervous tissue) Medulloblastoma origin(Youman)
ROOF
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 4: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/4.jpg)
It has a roof a floor and two lateral recesses
The roof superior and inferior medullary velum and cerebellar
vermis
Apex tented into cerebellum
The upper part of the roof superior cerebellar peduncles and
the superior medullary velum (thin sheet of white matter)
The inferior part of the roof Inferior medullary velum (non-
nervous tissue) Medulloblastoma origin(Youman)
ROOF
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 5: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/5.jpg)
The roof superior and inferior medullary velum and cerebellar
vermis
Apex tented into cerebellum
The upper part of the roof superior cerebellar peduncles and
the superior medullary velum (thin sheet of white matter)
The inferior part of the roof Inferior medullary velum (non-
nervous tissue) Medulloblastoma origin(Youman)
ROOF
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 6: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/6.jpg)
FLOOR OF FOURTH VENTRICLE
Each inferolateral margin of the floor is marked by a narrow white ridge called taenia
The right and left taeniae meet at the inferior apex of the floor to form a small fold
called the obex
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 7: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/7.jpg)
The lateral recesses pouches below the cerebellar peduncles
Luschka CPA
The ventral wall of each lateral recess is formed by the junctional
part of the floor and the rhomboid lip
The rostral wall of each lateral recess Caudal margin of the
cerebellar peduncles
The peduncle of the flocculus which interconnects the inferior
medullary velum and the flocculus crosses in the dorsal margin of
the lateral recess
LATERAL RECESS
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 8: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/8.jpg)
LATERAL RECESS
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 9: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/9.jpg)
The caudal wall is formed by the tela choroidea which stretches
from the taenia and attaches to the edge of the peduncle of the
flocculus
The rootlets of the glossopharyngeal and vagus nerves arise ventral
and the facial nerve rostral to the choroid plexus which extends
through the lateral recess and the foramen of Luschka into the
CPA
The fibers of the vestibulocochlear nerve cross the floor of the
recess
LATERAL RECESS
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 10: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/10.jpg)
LATERAL RECESS
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 11: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/11.jpg)
The cavity or fossa of the fourth ventricle communicates with the
third ventricle superiorly as a continuation of the cerebral aqueduct
Inferiorly it extends as the central canal of the brainstem which in
turn runs through the vertebral column
The cavity also communicates with the subarachnoid space through
the three apertures
CAVITY
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 12: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/12.jpg)
Foramina of the fourth ventricle
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 13: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/13.jpg)
First described during the 19th century
Franc ois Magendie French physiologist Magendie (1783-1855)
Pioneer of experimental physiology
Hubert von Luschka German anatomist (1820-1875)
Rhoton provided detailed descriptions of the neurosurgical anatomy
of the fourth ventricle and its foramina
FORAMINA OF 4TH VENTRICLE
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 14: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/14.jpg)
The choroid plexus of the fourth ventricle consists of several
segments
Its lateral segments extend laterally through the foramina of
Luschka (protruding into the cerebellopontine angle below the
flocculus and behind the glossopharyngeal vagus and accessory
nerves) and
Its medial segments extend longitudinally through the foramen of
Magendie
The tonsillar parts of the choroid plexus are located anterior to the
tonsils and extend inferiorly through the foramen of Magendie
CHOROID PLEXUS OF 4TH VENTRICLE
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 15: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/15.jpg)
The PICA is intimately related to the inferior half of the roof
The PICA segment coursing in the cleft between the tonsil on one
side and the tela and velum on the opposite side is referred to as the
ldquotelovelotonsillar segmentrdquo3
This PICA loop which forms a convex rostral curve in its course
around the rostral pole of the tonsil is also referred to as either the
ldquocranialrdquo or ldquosupratonsillar looprdquo
VASCULAR RELATIONS
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 16: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/16.jpg)
PICA
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 17: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/17.jpg)
The main trunks of the anterior inferior cerebellar artery course near
the foramen of Luschka where they extend small choroidal
branches to the tela and choroid plexus in the lateral recess
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 18: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/18.jpg)
The largest vein of the
cerebellomedullary fissure
Originate nodule and uvula
courses laterally near the
junction of the inferior medullary
velum and tela choroidea
Courses dorsal or ventral to
the flocculus
CPA
Superior petrosal sinus
Venous system
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 19: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/19.jpg)
Ikezaki and co-workers classified posterior fossa ependymomas
into three groups based on location
(1)The lateral type presenting in the CPA characterized by a poor prognosis
secondary to involvement of cranial nerves and brainstem
(2) Ependymomas localized to the floor of the fourth ventricle with an
intermediate prognosis and
(3) Those localized to the roof of the fourth ventricle with the most favorable
outcome
Leptomeningeal dissemination
Medulloblastoma 33
Ependymoma 8 to 12
Spread and dissemination route
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 20: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/20.jpg)
Hydrocephalus is one of the conditions that can result from
blockage of the median and lateral apertures
In Arnold Chiari malformation (Type II Chiari malformation) the
medulla and the tonsils of the cerebellum come to lie in the
vertebral canal by descending through the foramen magnum
The median and lateral apertures are blocked by this condition
leading to obstruction of CSF flow
This causes internal hydrocephalus
Chiari II can also present with syringomyelia due to the
development of CSF-filled cyst or syrinx
CLINICAL IMPORTANCE OF 4TH
VENTRICLE
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 21: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/21.jpg)
PICA
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 22: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/22.jpg)
Medulloblastoma is the most common malignant brain tumour in
children which arises in the cerebellum and can therefore impinge
on the roof of the fourth ventricle
The area postrema of the caudal region of the fourth ventricle is also
of clinical significance because of its role in the control
of vomiting
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 23: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/23.jpg)
In adults the occlusion is rather acquired than congenital linked to
infection head trauma intraventricular haemorrhage tumours or
Arnold-Chiari malformation
Despite its rare occurrence congenital imperforation or
membranous obstruction of the foramen of Magendie must be
considered as a possible etiology of chronic hydrocephalus in adult
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 24: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/24.jpg)
Main pathological conditions affecting the
foramina of the fourth ventricle
1 Occlusion
(Infection head trauma intraventricular haemorrhage space-
occupying lesions congenital anomalies)
2 Membrane obstruction
3 Congenital imperforation (agenesis)
4 Idiopathic stenosis
5 Arachnoid adhesions
6 Cystic dilation
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 25: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/25.jpg)
Tumors of the ventricular system account for less than 1 of
intracranial lesions most of which are benign and slow growing
14 of all ventricular tumor occurs within the fourth ventricle
Tumor originating in 4th Ventricle
1 Medulloblastoma most common childhood
2 Ependyoma most common adults
3 Hemangioblastoma
4 Epidermoid cyst
Tumor expanding inside the 4th Ventricle
1 Astrocytoma
2 Oligodendroglioma
3 Exophytic cavernous malformation
Tumor of 4th venticle
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 26: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/26.jpg)
Medulloblastoma
Usually originates from inferior medullary velum from germinative cells
originating in the neuroepithelial roof of the fourth ventricle and grow anteriorly
into the fourth ventricle
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 27: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/27.jpg)
Hemangioblastoma
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 28: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/28.jpg)
CHOROID PLEXUS PAPILLOMA
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 29: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/29.jpg)
APPROACH
TO
4th VENTICULAR TUMOR
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 30: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/30.jpg)
bull Midline pathology of the fourth ventricle that arises from the
cerebellar vermis or brainstem
bullTumors Medulloblastoma ependymoma-subependymoma as-
trocytoma choroid plexus papilloma hemangioblastoma dermoid-
epidermoid cysts brainstem glioma and metastatic lesions
bull Vascular lesions Arteriovenous and cavernous malformations
bull Inflammatory and infectious conditions Cerebellar and brainstem
abscesses
bull Traumatic or spontaneous hematomas
INDICATION
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 31: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/31.jpg)
CSF diversion endoscopic ventriculostomy external ventricular
drain or permanent ventriculoperitoneal shunt
followed by microsurgical resection of the underlying ventricular tumor
Emergency Acute obstructive hydrocephalus or intratumoral
hemorrhage
INDICATIONS
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 32: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/32.jpg)
In the past operative access to the fourth ventricle was obtained by
splitting the cerebellar vermis or by removing part of a cerebellar
hemisphere
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 33: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/33.jpg)
Dandy Median suboccipital craniectomy and splitting the vermis
TRANSVERMIAN APPROACH
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 34: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/34.jpg)
Transvermian approach provided slightly better visualization of the
medial part of the superior half of the fourth ventricular roof
(Disadv Lateral recess)
In cases where a tumor is located around the fastigium or originates
from the vermis
ADVANTAGES
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 35: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/35.jpg)
It avoids complications related to injuries of the posterior inferior
cerebellar artery (PICA) branches to the brainstem and the inferior
and middle cerebellar peduncles
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 36: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/36.jpg)
TELOVELAR(TRANSCEREBELLO-MEDULLARY FISSURE)
APPROACH
1980Rhoton AL Jr
This approach is identical to traditional midline approaches
Preserve the cerebellar tissue Anatomic plane through the tela choroidea and velum
interpositum
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 37: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/37.jpg)
Opening the CMF safe retraction of the cerebellar hemisphere
Good visualization of lateral recess
The cerebellar mutism syndrome Avoids vermian split
Early vascular control
ADVANTAGES OF TELOVELAR
APPROACH
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 38: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/38.jpg)
STEPS OF TELOVELAR APPROACH
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 39: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/39.jpg)
POSITIONING
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 40: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/40.jpg)
INCISION
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 41: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/41.jpg)
The craniotomy includes opening of the foramen magnum dorsally
and is larger in the superior portion than in the inferior
CRANIOTOMY
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 42: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/42.jpg)
Dural opening is usually performed in a Y-shaped fashion
Bleeding from the occipital sinus can be controlled with silver dural clips or bipolar coaguation or running silk suture
DURAL OPENING
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 43: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/43.jpg)
DECOMPRESSION OF CISTERNA
MAGNA
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 44: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/44.jpg)
Opening techniques for the telovelar approach depending on different
targets
Matsushima T et al
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 45: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/45.jpg)
Small arachnoid trabeculae around the tonsil is sharply cut and cerebellar tonsil is gently elevated off its inferior fixation
The superior portion of the tonsils is separated from the cerebellar vermis on both sides to gain access to the tela choroidea
Careful inspection of the tela reveals small branches of the PICA that supply the choroid plexus
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 46: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/46.jpg)
In similar fashion the
caudal loop of the PICA
is freed from the
neuraxis by incising
small arachnoid
trabeculae while slightly
retracting the tonsils
laterally
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 47: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/47.jpg)
The uvula of the cerebellar
vermis is elevated gently with
a self-retaining retractor and
the arachnoid between the
uvula and the tonsil is
gradually incised to expose
the course of the PICA
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 48: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/48.jpg)
The telovelar junction is
visualized
The superior medullary
velum may be further
divided to allow for more
rostral exposure of the
fourth ventricle
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 49: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/49.jpg)
When the roof of the fourth
ventricle is adequately opened to
allow for exposure of the tumor
the interface of the tumor and
the brainstem is inspected
Cottonoid strip along floor and cervicomedullary junction
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 50: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/50.jpg)
Superior and lateral edges adherence to the cerebellum
Larger tumors debulk the tumor lateral margins
A point of origin of the tumor more adherant part
TUMOR INSPECTION
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 51: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/51.jpg)
Hemostasis cerebellum bipolar cautery or tamponade
Inspect aqueduct blood clot
Saline irrigation until clear
Finishing touch
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 52: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/52.jpg)
Closure
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 53: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/53.jpg)
Retraction injury to cerebellar tonsils vermis and cerebellar peduncles
Injury or occlusion of posterior inferior cerebellar arteries from
retraction
Injury to the floor of the fourth ventricle (brainstem)
Tracking of blood into third and lateral ventricles that may produce
hydrocephalus
Injury to the transverse sinus during the craniotomy
Significant blood loss or air emboli from occipital sinus or midline
occipital bone
Tumor dissemination along foramina and obex
AvoidancesHazards Risks
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 54: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/54.jpg)
1 Postoperative hematoma
2 CSF leak
3 Infection
4 Cranial nerve deficits or other brainstem deficits
5 Hydrocephalus
6 Cerebellar deficits
7 Supratentorial epidural hematoma
8 Tumor residual or recurrence
9 Posterior inferior cerebellar artery or vertebral artery infarction
10 Cerebellar edema
Complications
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 55: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/55.jpg)
Medulloblastoma (13) ependymoma (10) and then choroid plexus
papilloma (2)
GTR8 cases (32) near total (˃80 of tumor volume) in 14 cases
(56) and subtotal excision (˂80 of tumor volume) in 3 cases
(12)
Cerebellar mutism in 2 cases (8) facial palsy 2 cases(8)
postoperative bulbar affection 3 cases (12)
Mortality 2
Conclusion Telovelar approach access Low incidence of CM
Retrospective study
25 cases with midline posterior fossa tumors
2012-2014
Neurosurgery Department Cairo University Egypt
Refaat MI Elrefaee EA Elhalaby WE (2016) Telovelar Approach for Midline Posterior Fossa Tumors in Paediatrics 25 Cases Experience J Neurol Disord 4315 doi 1041722329-68951000315
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References
![Page 56: 4 th ventricle- Anatomical and surgical perspective](https://reader033.vdocuments.us/reader033/viewer/2022051318/5a65f7d97f8b9aaf638b693d/html5/thumbnails/56.jpg)
Thank you
1 Mussi AC Rhoton AL Telovelar approach to the fourth
ventricle microsurgical anatomy JNS 200092(5)812-23
2 Schmidek and Sweet operative technique 6th Edn
3 Refaat MI Elrefaee EA Elhalaby WETelovelar Approach
for Midline Posterior Fossa Tumors in Paediatrics 25 Cases
Experience J Neurol Disord 20164315
References