spinal cord arteriovenous malformations
TRANSCRIPT
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SPINAL AVM – CLASSIFICATION AND MANAGEMENT
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Spinal Cord Vascular Malformations
It represent a heterogeneous group of non-neoplastic vascular
abnormalities
Spinal arteriovenous malformation (AVM) is an abnormal
tangle of arteries and veins in which the arteries feed directly
into the veins with abnormal intervening capillary bed.
AV fistula (AVF): direct communication between artery & vein
AV malformations (AVMs): multiple complex communications
Nidus: the core of an AVM that appears angiographically and
anatomically as a conglomeration of vessels because of the
superimposition of arteries and veins.
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Incidence
Rare cause of neurologic dysfunction
5% of all intraspinal pathology
Occur throughout the spine
Affect any age group, majority: 30-50
Better diagnosis and management with improved
techniques of spinal angiography, MRI, MRA
and endovascular surgery
O`Toole and McCormick. Chapter 83: Vascular Malformations of the Spinal Cord. Rothman-Simeone The Spine. 5th Edition
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HISTORY AND CLASSIFICATION
Classification of spinal AVM has evolved with thetechnology available to study them.
Earliest studies were based on postmortem examinations.
1888, Gaupp described them as “hemorrhoids of the piamater spinalis”.`
In 1914, Charles Elsberg performed the first successfuloperation on a spinal cord AVM.
1925 – Sargent: classified 19/21 cases as venous angiomas
1943 – Wyburn Mason classified AVMs into histologicalgroups arteriovenous angiomas and purely venousangiomas(more common)
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Baker –layton in 1967 classified AVM s into 3
categories:
Type 1 - single coiled vessel type
Type 2 - Glomus AVM
Type 3 - juvenile AVMs
• 1977 – Kendall and logue identified AVFs in the
dural sleeve of spinal nerve roots which were
consistent with single coiled vessel type of
AVMs.
HISTORY AND CLASSIFICATION
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HISTORY AND CLASSIFICATION
Two additional advances in the last 25years
1977 – Recognition by Djindjian that some
intradural lesions that were previously
considered AVMs of the spinal cord are actually
simple AVFs in the pia(Perimedullary AVFs)
Recognition of cavernous angiomas
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Classification: Berenstein A(1999)
Spinal cord vascular malformation
Isolated - AVMs and Av fistulas
Multiple – Metameric (Cobb syndrome and otherassociations) and non metameric (Rendu –Osler– weber syndrome)
• Spinal cord telangiectasias
• Cavernomas
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Classification: Anson, Spetzler(1992)
Most widely accepted. 4 types
Type 1: AV Fistula located between a duralbranch of the spinal ramus of a radicular arteryand an intradural medullary vein
Type 2 : Intramedullary glomus malformationwith a compact nidus within the substance of thespinal cord
Type 3: Juvenile or combined AVMs -extensiveAVM often extending to the vertebra orparaspinal tissues.
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Type 4 : Intradural perimedullary arteriovenous
fistula
A – simple fistula fed by a single arterial
branch.
B – Intermediate sized fistula with multiple
dilated arterial feeders
C – Large perimedullary fistula with multiple
giant arterial feeders.
Classification: Anson, Spetzler(1992)
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MODIFIED CLASSIFICATION OF
SPINAL CORD VASCULAR LESIONS
1. NEOPLASTIC VASCULAR LESION
• Hemangioblastoma
• Cavernous malformation
2. SPINAL ANEURYSM
3. AVF :
Extradural
Intradural
• Ventral (Small/Medium/Large shunt)
• Dorsal (Single/Multiple feeder)
4 AVM
• EXTRADURAL-INTRADURAL
• INTRADURAL
• CONUS MEDULLARIS
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Arterial Anatomy
1. Anterior spinal artery: Arises from the fusion of a contribution from each of the vertebral
arteries
Supplies the ventral 2/3 of the cord
Important contribution to the ASA is from the artery of Adamkiewicz, which may arise anywhere from T8 to L1, more often on the left side.
The anterior spinal axis in the anterior commissure of the spinal cord and gives rise to perforators throughout its length.
2. Paired posterior spinal arteries: run the length of the spine
supply the posterior 1/3 of the cord
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Arterial Anatomy
3. At each segmental level: a dorsal ramus of the segmental artery enters the intervertebral foramen and gives rise to 3 branches:
Dural branch: to dura
Radicular branch: to nerve root
Medullary branch: Augments the flow to the anterior spinal artery
During the 3rd stage of fetal development, most of the medullary branches involute distal portion of the cord relatively ischemic
Somewhere between T8 & L2, especially on the left: the medullary branch does not involute and becomes the artery of Adamkiewicz
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Arterial Anatomy
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Venous Anatomy
Coronal venous plexus: A plexus on the cord surface
Formed by coalescence and anastomosis of radial veins
Epidural venous plexus: At segmental levels, medullary veins leave the coronal plexus
and exit the intervertebral foramen to join the epidural plexus
The plexus communicates with the venous sinuses of the cranial dura
It drains into the ascending lumbar veins and the azygousvenous system
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Pathophysiology of Symptoms
Depends on the type of the AVM
High-flow:
Ischemia
Hemorrhage
Slow-flow:
Venous congestion
Mechanical compression of the spinal cord and
roots
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CLINICAL PRESENTATION
The clinical signs are due to:
(1) SAH;
(2) haematomyelia;
(3) steal into AVF/AVM;
(4) venous hypertension;
(5) thrombosis of draining vein,
(6) pressure of aneurysm, venous or arterial, true or false;
(7) arachnoiditis;
(8) syringomyelia and
(9) Foix-Alajouanine syndrome, a result of chronic venousischaemia of the spinal cord.
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Dural Arterio-
Venous Fistula
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Type I (Dural AV Fistula)
The most common type
60% of spinal AVF/AVM
Single AV connection within the
dura of the nerve root sheath
Results in dilated arterialized
coronal venous plexus
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Dural AV Fistula
Medullaryvein
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Spinal Dural Arteriovenous Fistula
Represent at least 35% of all spinal vascularmalformations in large series, although some estimatesrange as high as 80%
Most commonly occur at thoracolumbar levels, usuallybetween T5 and L3
It represents an AV shunt that occurs within duralcovering of spinal cord, below and medial to the pedicle.
Located adjacent to intervertebral foramen or withindural root sleeve, with arterial supply arising from duralbranch of radicular artery.
An intradural vein drains the shunt directly into the pialveins of the cord
J Neurosurg 1983;59:1019-1030.06-Jan-16
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Pathophysiology
AV shunting result in venous engorgement andvenous hypertension involving the spinal cord(Venous congestion, steal phenomenon, ischemiaand hemorrhage)
Most often, no direct arterial supply to the spinalcord itself originates from the radicular arteryfeeding an SDAVF.
In 10% to 15% of cases, however, SDAVF is fedby a radicular artery that also supplies spinal cordvia a radiculomedullary or radiculopial branch
Radiology 1985;154:687-689.06-Jan-16
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SUBACUTE NECROTIZING MYELOPATHY
VENOUS HYPERTENSIVE MYELOPATHY &
Cord edema, stagnation of bloood flow , blood – CNS disruption
Intramedullary vasodialation, Loss of autoregulatory capacity
Tissue perfusion ( hypoxia )
Intramedullary arteriovenous pressure gradient
Venous engorgement & venous hypertension
Increased pressure & engorgement of pial veins
Intradural vein Pial veins
PATHOPHYSIOLOGY
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Clinical presentation
Most common spinal vascular anomaly in older adult, afflicts malesin 80% to 90% of cases
Presents after the fourth or fifth decade;
Chronic progressive myelopathy leads to progressive lower extremityweakness, often characterized by both UMN & LMN signs.
Localized or radicular back pain, bowel, bladder, and sexual
dysfunction -Often exacerbation by excersise
Claudication pain is a common presentation in dural AVF.
Claudication pain and neurological deficit may be worsened by a
heavy meal
Lead to paraplegia within 2 – 4 years.
Never bleeds.
15% of the patients have rapid neurological worsening and is called
Foix alajouanine syndrome and is due to venous congestion andshould be treated immediately 06-Jan-16
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Imaging
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Anteroposterior (A) and lateral (B) lumbothoracic spine radiographs reveal medial erosion of the pedicles (A, arrows) and scalloping of the posterior aspect of several vertebrae (B).
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MRI
Conus and lumbar enlargement of the cord are almost uniformly affected; however, abnormal signal may extend into upper thoracic cord levels – Non specific.
Hallmark of diagnosis is demonstration of dilated pialveins of cord, most commonly along dorsal surface.
MR reflect pathophysiologic features of SDAVF including cord edema and venous hypertension with engorgement of the pial veins
Ischemia and venous infarct can occur.
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SPINAL ANGIOGRAPHY :
•AVF shunt below or medial to the pedicle .
•The draining vein is almost 10 times larger than feeding
artery.
•The arterial flow is slow .
•Recently, the use of time-resolved imaging of contrast
kinetics (TRICKS) has improved the detection rate and
accuracy of MRA and DSA for diagnosis and localisation
is often unnecessary.
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Type II (Glomus AVMs)
Analogous to intracranial AVMs
Tightly packed nidus of dysmorphicarteries and veins in direct communication w/o capillary bed; over a short segment of the spinal cord
The nidus may be completely or partially intramedullary
Typically lie in the anterior half of the spinal cord and are supplied by one or two medullary arteries via the anterior spinal artery
Usually at the cervicothoracic junction
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glomus type
•Compact nidus
•Intramedullary
• Multiple branches of ASA
& PSA
•High pressure
•Relatively low resistance
•High blood flow
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Pathophysiology of Type II
Vascular steal mechanism: High-flow lesion; AVM
nidus acts as a low-resistance sump siphoning blood
away from the surrounding normal spinal cord
Dysmorphic vessels susceptible to hemorrhage
Mass effect: myelopathy or radiculopathy
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Clinical Presentation of Type II
Childhood or adult years
Acute presentation from subarachnoid or intramedullary
hemorrhage is most common
Acute onset of severe neck or back pain “coup de
poignard” approximates the level of AVM: typically the
first symptom of AVM hemorrhage
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Juvenile
Spinal
AVM
Intramedullary
& extramedullary
+/-
extraspinal
extension
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Vascular anatomy – Intradural AVMs
Juvenile type (TYPE 3):
These lesions are fed by multipleenlarged medullary arteries via theanterior and posterolateral spinalarteries and may have avoluminous nidus that completelyfills up the thecal sac.
The nidus also has interveningneural tissue.
These may frequently involvevertebrae and paraspinal tissues .
These lesions are high-flow AVMs;a spinal bruit may indicate theirpresence.
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JUVENILE SCAVM
EXTRADURAL-INTRADURAL AVM
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SYMPTOMS
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• MALE or FEMALE
• Age : 2 or 3 decade
Nearly 50 % < 16 years .
• 30 % weakness as initial symptoms
• 20 % Back pain at onset .
• Over 70 % develop sensory symptoms
• 50 % Spinal hemorrhage
• Bladder & bowel involvement
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•Slow flow AVM Myelopathic symptoms .
• High flow AVM Bleed:
•HEMORRHAGE :
•SAH OR intramedullary bleed ,
•High mortality ( 30 % )
•High rate of bleeding (40 % within first year )
ACUTE MEDULLARY SYNDROME .
May progress rapidly , or there may be partial
remissions.
Prognosis : Poor .
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Imaging
Flow voids representing enlarged arterial feeding vesselsand intramedullary nidus are well seen
Haemorrhage is also seen in various stages.
Nonhemorrhagic intramedullary signal abnormalityadjacent to the nidus and most likely indicates gliosis,edema, or areas of cord infarction.
Extension of nidus into extramedullary structures,paraspinal soft tissue structures, is also well seen on MR
Angiographic evaluation of delineation of all feedingvessels, aneurysms, locating the nidus within the cord,and mapping the size and location of draining veins.
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IMAGING : AVMs
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MRI : best noninvasive modility
Flow voids enlarged arterial feeding vessels
Intramedullary nidus
Recent / remote intramedullary hemorraghe
T2W Hyperintensity : gliosis, edema, infarction
Draining veins :
• Flow voids,
• Ectasia ,
• Mass effect,
• Thrombosis
Intramedullary contrast enhancement
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Juvenile-type intramedullary (AVM) of the cervical and thoracic segments Right vertebral arteriography,anteroposterior (A) and lateral (B) views,demonstrates the superior aspect of a large intramedullary AVM that extends from C4 to T2. The nidus of the AVM fills the spinal canal from front to back and from side to side.
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On sagittal T1-weighted
magnetic resonance imaging ,
the signal void from the AVM
clearly involves not only the
cross-sectional area of the spinal
cord but also the anterior and
posterior elements of the spine
and paraspinous soft tissue
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glomus type
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Selective spinal cord arteriogram demonstrating a
glomus-type intramedullary arteriovenous
malformation supplied by the anterior spinal
artery via the artery of Adamkiewicz
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Feature SDAVF SCAVM
Age >4th decade 2nd-3rd decade
Symptom onset Slow progressive Acute
Male predominance Yes (marked) Minimal
Hemorrhage No Yes (frequent)
Bruit No 5-10%
Origin Acquired Congenital
Site of nidus Dura, root sleeve Spinal cord
Medullary arterial supply involved
10-15% 100%
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Perimedullary
Fistula
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Perimedullary arteriovenous fistulas
Consist of direct AVF located on the cord and fed directly by arteries supplying the cord, most frequently the ASA
8-19 % of spinal AVM.
Single hole between one or more radiculomedullary arteries & perimedullary veins on the surface of cord .
Features that differentiate SCAVFs from both SDAVFs and SCAVMs Intradural location of shunt, constant involvement of arteries supplying
the spinal cord, and lack of intervening nidus
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AV fistula
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Etiology And Clinical Presentation
Believed to be congenital lesions, usually present in patients in their second through fourth decade
Most common neurologic presentation is one of progressive asymmetrical radiculomedullary signs involving lower extremities, reflecting the most common location of SCAVFs in the lower thoracic or lumbar region
Hemorrhage is also common and has been noted in nearly one third of patients at presentation
Three subtypes have been identified based on the size and number of vessels involved
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Perimedullary AVF
A – Simple perimedullary fistula fed by single arterial branch. (Venous drainage minimally dilated)
B – Intermediate sized fistula with multiple dilated arterial feeders. (ASA & PSA are mildly dilated and draining vein markedly dilated)
C – Large perimedullary fistula with multiple giant arterial feeders.(Main supply is ASA and draining proximal venous segment is ectatic)
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SYMPTOMS
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Young adults , 2 – 4 Decade
No sex predilection .
Most common presentation :
• Progressive asymmetrical radiculomedullary signs,involving lower extremities .
• Progressive paraplegia without remission.
• Impaired venous return & long intradural course ofthe venous drainage may be responsible forascending myelopathy & spinal cord ischaemia .
• Spinal SAH In 1/3 patients .
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IMAGING
Flow voids - enlarged feeding and draining vessels of
SCAVF.
Intrinsic cord signal abnormality and evidence of
hemorrhage may also be present.
Small size of some lesions and lack of nidus may make
differentiation from SDAVF difficult.
Abnormal enhancement of the cord may be present.
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PERIMEDULLARY
AVF
3D PC MRAT1WI
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MRISCAVM PMF SDAVF
Flow voids + + +
Parenchymal signal changes
+ + +
Aneurysm + + -
Hemorrhage + + -
Nidus in the cord - -
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Radiological differences between duralAVM and Intradural Avm
Dural AVM Intradural AVM
Site of nidus Lateral canal
100%
Within cord 80%
Level of spine Lower half diffuse
Rapid flow 0 80%
Assoc aneurysm 0 44%
Supply by
medullary artery
15% 100%
Route of drainage Rostral 100%
Caudal 4%
Rostral 81%
Caudal 72%
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Cavernous Malformation
Cavernous malformations(CMs) are slow flow vascularmalformations without AVshunting
3% to 5% of CMs involve thespine
Site- Most often intramedullaryand occur proportionallythroughout the cord
CMs of the spine have beennoted to preferentially affectfemales
It can arise denovo, postradiotherapy and post traumatic.
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Clinical presentation
Symptoms may begin at any age, patients most oftenpresent in the fourth decade
Acute presentation is probably secondary to hemorrhageeither within vascular spaces of malformation or intosurrounding parenchyma (hematomyelia)
Progressive myelopathy may result from growth orenlargement of the lesions by several mechanismsincluding vessel dilation, repeated hemorrhage, orcapillary proliferation
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IMAGING
Varies in size from mm to cms.
Well demarcated with low grade hemorrhage of
varying ages
Surrounded by hemosiderin stained gliotic neural
tissue.
Histology show single cell layer to hyalinized,
thickened walls containing densely packed
collagen but no elastic or smooth muscle fibres.
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Cavernous Malformation- treatment
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They are not subjects for endovascular treatment, and
surgical resection is advocated for symptomatic lesions.
It is generally reserved for symptomatic lesions
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AVM/AVF-Treatment
Treatment planning for spinal vascular
arteriovenous lesions is based on
The hemodynamics of the lesion,
Location in the axial and longitudinal plane, and
The angioarchitecture.
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EMBOLIC AGENTS
Particulate materials Poly vinyl alcohol(150-250micro) :Temporary & Reduces arterial steal
safely.
Gelfoam
Sponge microparticulate
Balloon occlusion
Liquid agents N-butyl cyanoacrylate (NBCA) : If AVM is supplied by only PSA
ethylene vinyl alcohol copolymer)
If AVM is supplied by ASA , embolization only if : Normal anterior RMA supplying above & below the
AVM. Superselective catheterization , close to nidus.
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Treatment - Dural AVF
Goal of treatment of spinal dural AVF is permanentelimination of of venous congestion of the spinalcord
Simple interruption of the AvF produces permanentresolution of venous congestion and improvementof myelopathy.
Medullary vein(arterialised) is coagulated
Neurological outcome is closely related to preopfunction.
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Endovascular occlusion of SDAVF is possible in
more than 80% of cases and can be accomplished
at the same time as the diagnostic angiogram using
permanent liquid embolic agents such as
NBCA(N-butyl cyanoacrylate) or ONYX.
Perimedullary venous thrombosis.
Clinical symptoms may worsen.
Post procedure anticoagulation for 3 months.
Treatment - Dural AVF
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TREATMENT : AVMs
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Should be pursued aggressively because of the poor
outcomes in untreated patients.
AIM : To suppress the risk of hemorrhage & arrest
progression of neurological defecit .
Maximum suppression of arterial steal may reverse a
progressive neurological defecit.
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EMBOLIZATION
• Method of choice .
• Risk of embolization is 3 to 5 times lower
than surgery .
• Angiographic criteria for endovascular
approach is
Enlarged prominent ASA
Multiple commissural branches
participating in AVM .
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TREATMENT : Perimedullary AVF
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Type I: Embolisation is not indicated if the fistula is surgically accessible since
surgery is the safer and more reliable treatment.
• Catheterisation in the anterior spinal artery can be difficult and is always
hazardous.
• Fistulas situated on the ventral cord surface are candidates for embolisation
which has been performed with particles (as a presurgical manoeuvre) or
NBCA
Type II: If the fistula is situated on the dorsal surface of the cord, surgical ligation
and embolisation are of equal value and efficacy.
• Ventral lesions are difficult cult to approach surgically but difficult cult to
completely exclude by embolisation, if there are multiple feeders
Type III: The high-flow and dilated vessels in this type makes surgery difficult, and
embolisation with coils or liquids is usually performed as curative or presurgery
procedures.
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TREATMENT : Perimedullary AVF
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SURGERY :
1. Smaller lesion ,
2. AVF I & II , located posterior to the spinal cord
3. Endovascular treatment failed in AVF III .
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Intradural arteriovenous fistula at surgery (A) Before, (B) After
obliteration
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Summary of outcomes of treatments for spinal
vascular malformations
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Intramedullary AVM Surgery Curative resection
if possible
Embolisation (curative or
palliative)
Particles: high recurrence
NBCA: better cure rates
Onyx: no data
Perimedullary AVF Type I. Surgery (or embolisation)
Surgery first-line
treatment if AVF accessible
NBCA embolisation, but
particles may be safer
Perimedullary AVF Type II EVT (or surgery) NBCA, particles or surgery
Perimedullary AVF Type
III
EVT (surgery if
incomplete)
Coils, (balloons), NBCA or
Onyx
DAVF EVT (surgery if recurrent) NBCA or Onyx
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Indications for occluding only the feeding vessels
Dural AVM
Intramedullary diffuse AVM
Combined AVM
Conus medullaris AVM
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Complications
Complications that result from open surgical ligation orresection
Infection of meninges (meningitis)
Cerebrospinal fluid leak
Wound dehiscence
Complications that result from the endovascular technique
Femoral hematoma
Pseudoaneurysms and thrombosis
Arterial dissection
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Stereotactic radiosurgery
Single high dose SRS
20 to 30% rate of occlusion.
Hypofractionated irradiation
Internal fiducial markers and image‐guided
radiation allow stereotactic irradiation for spinal
disease with real‐time verification and an
accuracy of ±1 mm for every 0.03 seconds
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Type Typical
location
Vascular
supply
Presentation &
course
Clinical
associations
Treatment
DAVF Lumbar,
thoracic
Dural
arteries
Chronic
myelopathy
None 1.Embolizati
or
2.Surgery
AVM Cervical,
thoracic,
Lumbar
Spinal
arteries
(ASA,
PSA)
Acute;
hemorrhage
common
Vascular
syndromes;
paraspinal
involvement
rarely
1.Embolizati
or
2.Surgery
PAVF Lumbar,
thoracic
Spinal
arteries
(ASA >
PSA)
Acute or
chronic; may
hemorrhage
None 1.Embolizati
or
2.Surgery
CM Cervical,
thoracic,
Lumbar
Minimal Acute or
chronic; may
hemorrhage
Intracranial or
familial CM
Surgery
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Grade Gait
0 Normal
1 Leg weakness, abnormal gait or stance, but no restriction of activity
2 Restricted activity
3 Requiring 1 stick for walking
4 Requiring 2 sticks, crutches, or walker
5 Confined to wheelchair
Grade Micturi tion
0 Normal
1 Hesitancy, frequency, urgency
2 Occasional urinary incontinence or retention
3 Total incontinence or persistent retention
Modified Aminoff-Logue grading scale
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THANK YOU
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