cerebrospinal fluid
TRANSCRIPT
Journal club
CEREBROSPINAL FLUID: IMPLICATIONS IN ORAL AND MAXILLOFACIAL SURGERY
M. Todd Brandt, W. Scott Jenkins, Tirbod T Fattahi, Richard H Haug.JOMS 2002; 60: 1049-1056.
Introduction CSF is an essential component of the nervous
system. Serves as cushion, lubrication for cerebral
hemisphere and meningeal layer. CSF fistula and leaks are documented in variety
situation trauma, skull base surgery, functional endoscopy, spontaneous.
Galen in 2nd century AD, first documented the description of CSF fistula(rhinorrhea)
First correlation of CSF rhinorrhea with craniomaxillary trauma was made in 17th century by Bidloo & Elder.
CSF fistula is serious potential fetal condition, successful management requires through understanding of pertinent anatomy & path physiology.
This article reviews the anatomy & path physiology of CSF , clinical significance of CSF fistula , highlights on etiology and management of CSF leaks seen in OMFS.
Anatomy
CSF is formed in the choroid plexus around the lateral ventricle and lesser amount by 3rd & 4th ventricle. Partly by arachnoid villi with rate of 0.35-0.40ml/min.
Choroid plexusLateral
ventricle Third
ventricle Forth
ventricle
Circulation & absorption of
CSF
Lateral ventricles
Intra ventricular foraminaMonroe foramina
3rd ventricles
Cerebral aqueduct of midbrain
4th ventricles
Tentorial notch
Inferior surface of cerebrum
Superolateral surface of cerebrum
Arachoid granulations
Superior sagittal sinus
Central canal of spinal cord
Subarachnoid space around spinal cord & cauda equina
Veins of spinal cord
Foramina MagendieForamina Luschka
Sub arachinoid space
laterally
medially
Cerebrospinal Fluid Circulation.flv
Physiology CSF termed as third circulation. Clear fluid bathing the brain & meninges produced
on daily basis in ventriculocisternal portion of nervous system.
In adult avg intracranial volume is 1700ml, CSF makes about 5-10% volume (50-160 ml).
Rate of formation is 20-22ml/hr or 500ml/day or 0.35-0.40 ml/min.
CSF as a whole is renewed 4-5 times a day. In recumbent position intra cranial pressure is 8-12
mm Hg or 110-150 mm H2O (ie equilibrium to capillary pressure)
Autoregulation maintains the intracranial pressure irrespective of ↑ arterial pressure.
Co2 has profound effect on the CSF pressure. Hyperventilation: rapid ↓ in Pco2, ↑ pH & ↓
the CSF pressure.
Function of CSF:1. Serves as water cushion for brain & spinal
cord protect from blunt force trauma.
2. Provides the media to support the nervous system in closed bony cavity and protect by countercoup mechanism.
3. No lymphatic channels in nervous system , serves to remove the cerebral metabolic waste.
4. Active transport & passive diffusion allows exchange of electrolyte and fluid between plasma & extracellular space around choroid cell.
Various constituent of CSF.
Constituents CSF Serum Nasal secretion
Osmolarity (mOsm/L)
295 295 277
Na (mEQ/L) 140 140 150
K (mEQ/L) 2.5-3.5 3.3-4.8 12-41
Cl (mEQ/L) 120-130 100-106 119-125
Glucose (mg/100ml) 58-90 80-120 14-32
Albumine (of total protein)
50-75% 55% 57%
Total protein (mg/dL) 5-45 6-8.4 335-636
IgG (mg/100ml) 3.5 1140 51
B2 Transferrin 15 0 0
Incidence of CSF leak
CSF not common in all the trauma. Reports suggests 80% CSF leaks are direct results of
trauma ( craniomaxillary trauma- naso-orbito-ethmoidal #, postrior table frontal sinus #, skull base #)
closed head injury with basilar skull # and CSF leaks range from 2%-30%.
16% occurs secondary to surgery (iatorgenic nasal, paranasal, skull base surgery, functional endoscopic procedure)
remaining 4% spontaneous in origin(hydrocephalus, brain tumor, congenital anomaly)
Pediatric population presents with lower CSF leaks as facial skeletal development not reached the maturation & sinus pneumatization is incomplete,
Patho-physiology
It presents as CSF Rhinorrhea or CSF otorrhea.
most of times, occurs through anterior cranial fossa as at this region dura is tightly adhered to thin bone of cribriform plate and roof of ethmoid.
factors affecting nature of leak- Disruption of arachinoid & dura laceration,
tear in periosteum & mucosa. Degree of displacement of bony
fragments. Intracranial pressure Increased production of CSF
Classification
Ommaya classification system for CSF leak (1964)
Traumatic (80-90%) Non-traumatic (10-20%)
Accidental (Cranimaxillofacial fractures)
High pressure leaks1. Tumors2. Hydrocephalous3. Benign intracranial
hypertension
Iatrogenic (neurosurgical & functional endoscopic procedures)
Normal pressure leaks1. Congenital anomaly2. Focal atrophy3. Osteomyelitic erosion
Evaluation Clinical presentation
Clinical/Laboratory identification
Imaging
1. Otorrhea (25%), rhinorrhea (68%)
2. High suspicious with epistasis, pharyngorrhea, hemotympanum , battels sign, post traumatic serous otitis media.
3. CSF leaks should be assumed until ruled out.
Clinical-1) Reservoir sign2) Target sign (ring test)3) Altered ICP causes
headaches.4) Low pressure- headache
to be relieved by staining or performing Valsalva movement .
5) High pressure- headache relieved by release of CSF eg lumbar puncture
Laboratory-6) Glucose CSF conce ≥
plasma7) ↓Protein & K+ level8) β2 transferrin
1) Plane radiographs , CT scans: disruption of bony architecture, air or fluid level, tumor masses.
2) Cysternography :a. non radioactive dyes- Methylene blue,
phenol sulfonphthalein, flurescin.
b. Radioactive agent- Indium 11diethyleen
triaminic penta acetic acid (DPTA), technetium 99m-DPTA.
c. Combination of imaging along with contract medium (metrizamide)
Clinical management-
Conservative medical approach
Surgical intervention
Conservative medical approach Strict bed rest Head elevation 35 ° -45° Instruction to avoid activity that ↑ ICP
(coughing, nose blowing, sneezing, straining) Stool softener Acetazolamide (↓ CSF production ) Incidence of meningitis is 3%-50% and
mortality associated with post traumatic meningitis is 10%
Antibiotic prophylaxis is not recommended Clemenza et al
Protocol for surgical intervention Spontaneous closure of CSF fistulas within 48 hrs =
68%, 1 week = 85%. With reduction of craniofacial fracture CSF leaks
resolve spontaneously During reduction any suspicion regarding posterior
frontal table, orbito-ethmoidal #, fistulas are obliterated with galeal flap or fat.
If conservative management of facial # to slow the leak with 72 hr, lumbar subarachnoid drain placed ( if no indication for craniotomy)
Persistent leak > 8days despite of subarachnoid lumbar drain, craniotomy is require to repair the CSF fistula.
Surgery can be performed extra cranially ( endoscopic or transfacial) intracranially (craniotomy)
Patient selection for surgical repair Complication of CSF fistula – tension meningitis,
pneumocele. ↓ Incidence of meningitis (9%), {post traumatic
meningitis organism asso. Pneumococcous species} Repair of basal dural tear can prevent meningitis
(Teasdaie & Jennett) Classification of compound skull fracture by Sakas et al
I- Cribiform II- Fronto-ethmoidal III- lateral frontal IV- complex(any combiantion of above).
Type I are more prone fro infection than type II & III (near to sagittal midline are prone for infection)
Large fracture with max bone displacement (> 1 cm any plane .
Patient with transient rhinorrhea >8 days high risk of meningitis.
A. Lumbar drain- First indwelling catheter was reported in
1963. these are subarachnoid lumbar drain
effectively reduce the hydrostatic pressure.
Drains are kept for 4-10 days, drains CSF about 150 ml /day.
Risk of meningitis ↑ up to 10% when lumbar drains violate the subarachnoid space.
procedure may also present with complications like transient lumbar nerve root irritation, CSF overdraining leading temporary neurological decline.
B. Intracrainal repair- Dandy 1926, first described intracranial repair of
CSF fistula. Craniotomy
Advantage- Direct visualization of dural tear. Allows inspection of adjacent t brain injury Preferred when extracranial approach has failed.
Disadvantage- Asomia Intracranial hemorrahge Brain edema Skull base exposure Brain retraction
C. Extracranial repair- Dohlman 1948, first extra cranial approach
for CSF fistula repair. Appproaches- External ehtmoid-sphenoidal (medial
orbital incision, dissect orbital content posteriorly to gain ethmoidal labyrinth, fistula repair can be done with fascial late, muscle, fibrin glue)
Transmastoid (with high speed bur mastoid air cells are removed)
Transseptosphenoidal (trans nasal route),
D. Endoscopic repair Overall success 98%, Can address ethmoidal roof, cribiform
plate, sphenoidal defects Recommended when defect is < 1 cm.Disadvantage- Limited visualization Possible cerebral damage.
Post operative care
Patient going for the surgical repair shunts are kept at adjacent to direct repair
Shunts are kept appro 4-10 days Antibiotic prophylaxis for the patient with
higher risk of meningitis, preexisting sinusitis, compound skull base fracture with gross contamination.
Nafcillin, gentamicin, cephazolin excellent choice.
Surgical pack with antibiotic is kept to reduce bacterial endotoxin.
Thank you…