CSF is a clear fluid that cushions the brain and circulates through the ventricles and subarachnoid space. CSF leaks can occur due to trauma, spontaneous defects, meningoencephaloceles, or iatrogenically. Investigations like CT, MRI, and CSF tracer tests are used to locate the leak site. Small or localized leaks are managed conservatively but larger leaks or those at high risk for complications require surgical repair either extracranially via endoscopy or intracranially. Endoscopic techniques have high success rates using grafts, fat, fascia, or synthetic materials to plug the defect. Intrathecal fluorescein helps identify leak sites during surgery.

1. CSF
RHINORRHOEA

2. Learning objectives:
 Etiology
 Common sites
 Investigations to be done
 Surgical approaches for repair

3. CSF
 It is a clear , colourless body fluid found in the brain and spine.
 Produced in the choroid plexus of ventricles and reabsorbed
via the arachnoid granulations.
 Acts as a cushion for the cortex, providing mechanical and
immunological protection to the brain.
 Total volume:90 – 150 ml.
 Normal pressure: 50-150 mm of water

4. CSF BASICS: CIRCULATION
LATERAL VENTRICLES
THIRD VENTRICLE
FOURTH VENTRICLE
SUBARACHNOID SPACE OVER BRAIN AND SPINAL CORD
REABSORBED INTO VENOUS SINUS BLOOD VIA ARACHNOID
GRANULATIONS
AQUEDUCT OF
SYLVIUS
FORAMEN OF
LUSCHKA
FORAMEN OF MONRO

6.  SECRETED AT RATE OF ABOUT 20 ml/hr (300- 350 ml/day)
 TOTAL CSF REPLACED 3-5 TIMES A DAY.
 RISES ON COUGHING, SNEEZING, NOSE BLOWING, STRAINING ON
STOOLS OR HEAVY WEIGHT LIFTING.

8. Why repair:
 Risk of meningitis or other intracranial
complications.
 Socially troubling symptom.

9. ETIOLOGY:
 Traumatic ( skull base trauma)
 Spontaneous
 Meningoencephalocele
 Iatrogenic

11. TRAUMATIC:
 2% of head injuries and 12- 30% of the skull base fractures.
 Most as a result of blunt trauma.
 Most heal with conservative management (within 10 days).
 Bony spicules continue to hold the edges apart, persist for a longer time, need
surgical management.
 Common sites: fovea ethmoidalis > sphenoid> posterior table of frontal sinus.
 When heals spontaneously, only the sinus mucosal aspect of the defect closes as
dura does not regenerate, producing a relatively fragile closure.
 the layer may erode spontaneously by the pulsatile effect of the brain or
inflammation within the nose.
 The conservative management might be challenged towards a more active
intervention policy.

12. SPONTANEOUS LEAKS (IDIOPATHIC):
 Most commonly : cribriform plates, ethmoid roof and lateral wall
of the sphenoid sinus
 Cribriform plates : occur due to dilatation of the dural sheath
around the olfactory fibres.
 Sphenoid sinus leaks are mostly due to well pneumatised
sphenoid sinus or the arachnoid granulation in the floor of
middle cranial fossa.
 Most of the patients have undiagnosed benign raised
intracranial pressure (pre operatively diagnosed empty sella,
enlarged ventricles or diffuse erosion of the skull base)
 Associated with middle aged women with raised BMI.

13. MENINGOENCEPHALOCELE:
 Can be spontaneous ( congenital or acquired) or associated
with previous traumatic events.
 Consists of meninges and dura containing CSF with variable
amount of brain tissue prolapsing through the bony defect into
nasal cavity.
 Brain tissue contained within the encephalocele is invariably
non functional.

14. IATROGENIC:
 Frequently seen on the lateral wall of the olfactory fossa ,
anterior skull base weakened by anterior ethmoidal
neurovascular bundle, and posteriorly due to confusion
between anatomical relationship of posterior ethmoidal cell and
spenoid sinus.
 These leaks are apparent at the time of surgery and should be
addressed at the time of the surgery.
 Occurs mostly in the hands of inexperienced surgeons.

15. LEAKS ASSOCIATED WITH TUMORS:
 Tumors causing erosion of the skull base, or following induction
chemotherapy.
 Important: margins should be free of tumors for successful
closure.

16. APPROACH TO A PATIENT:
 HISTORY: Clear rhinorrhoea, posturally evoked
 May be increased on rising in the morning when patient bends
his head ( reservoir sign: fluid which had collected in the
sinuses, particularly sphenoid, empties into the
nose).

17. Difference between CSF and nasal
secretions:
FEATURE
S
CSF FLUID
NASAL
SECRETIONS
History:
Nasal surgery, head injury or
intracranial tumor
Sneezing, nasal stuffiness, itching
in the nose, lacrimation
Flow of
discharge
A few drops or stream of fluid
gushes down when bending
forward or straining, cant be
sniffed back
No effect on bending, can be
sniffed back
Character of
discharge
Thin, watery, clear, high sugar
content
Slimy or mucus stained
Presence of
beta transferrin:
Always present absent
Double target
sign Seen when mixed with blood
Absent

18. CSF TRACERS
 Visible dyes--- Fluorescein
 Radionuclide markers--- Radioactive iodine (I131), serum
albumin (RISA), technetium (99mTc)-labeled serum albumin and
diethylene-triamterene-penta-acetic acid (DTPA) and Indium
(In111)- labeled DTPA
 Radiopaque dyes--- Metrizamide

19. PRE OPERATIVE ASSESSMENT:
 Beta 2 transferrin: to confirm the CSF leak
 High resolution CT scan of the sinuses / T2 weighted MRI / CT
cisternography / Gadolinium enhanced CT cisternography: to
confirm the site of the leak

21. CONSERVATIVE MANAGEMENT
 Immediate post-traumatic leak (within
48 hours)
 Small post-operative leaks
 Poor risk patients for surgery
 Bed rest in head up position (300)
 Avoid coughing, sneezing, nose
blowing, straining
 Anti-tussive: for dry persistent cough
 Laxative: for constipation
 Medications: Acetazolamide,
Furosemide
 Repeated removal of CSF via repeat
lumbar taps or indwelling lumbar
sub-arachnoid drain
 Prophylactic antibiotics to prevent
meningitis
INDICATIONS TREATMENT

22. INDICATIONS FOR SURGICAL Rx

23. SURGICAL APPROACHES
 Precisely located leak
 Single, small leak (< 1
cm)
 Non-identifiable leaks
 Large leak (> 1cm)
 Multiple leaks
EXTRACRANIAL
(ENDOSCOPIC)
INTRACRANIAL
(PREFERABLY
INTRADURAL)

24. SURGICAL TECHNIQUES:
 Traditional management of CSF leaks in the anterior skull base was via
an anterior craniotomy and intracranial repair of the leak. Success
rate was around 70% with loss of smell.
 Endoscopic techniques have given a success rate of 90% at the initial
attempt and upto 97% with revision .
 Success rate for spontaneous etiology is the worst and are likely to
recur, as there can be multiple sites of weakness.
 Broad spectrum IV antibiotics are given along with induction of
anaesthesia and followed there after.

25. Endoscopic closure of the leak:
 Materials used: free mucosal grafts, pedicled mucosal grafts, fat, fascia,
muscle, and synthetic materials such as hydroxyapatite.
 Type of material did not appear to make a significant difference to the
success rate of the closure.
 Techniques used:
 On-lay technique
 Bath plug closure and fascia lata repair
 Under lay technique

27. INTRATHECAL FLUORESCEIN:
 Used for difficult to find CSF leak sites.
 Procedure:
lumbar drain is placed when patient is awake and
CSF is collected
0.2 ml of 5% fluorescein mixed with 10 ml of CSF
and is administered back slowly over 10 minutes
patient is kept in head down position for 1-2 hours
patient is put under anaesthesia

28.  Uses:
 Diagnosing a leak
 Disclosing its exact location
 Providing evidence of successful repair
 Complications:
 Paresthesia
 Tingling and numbness in the hands and feet
 Convulsions
 Can be seen better with a blue light filter.

29. Bath plug technique:
 Identification of the leak
 Enlargement of the dural defect so that the bony rim is clearly
seen.
 Small pieces of bones should be removed before the repair
 Nasal mucosa is stripped off the bony defect for around 5mm
 The fat lobule harvested (from ear lobule/ greater trochanter or
abdomen)
 A free mucosal graft (most common hadad- bassagasteguy flap)
or a fascia lata is given over the fat plug
 Fibrin glue is applied and gelfoam is placed over the mucosal graft
and fibrin glue reapplied.

34. SPECIAL STUATIONS:
MENINGOENCEPHALOCELES:
 Meninges and protruding brain tissue are
resected upto the skull base.
 Dural edges are cauterised with a suction
bipolar to ensure hemostasis.
 Assessment needs to be done whether edges
of the prolapsed brain tissue are in contact
with the edges of the skull base defect and
whether it is adhesive to the dura surrounding
it.
 For larger defects (>2cm) ,a 2nd layer of fascia
lata or a pedicled septal flap is placed over the
fascia lata followed by tissue glue.

35. Schematic diagrams depicting the different grades of CSF leak and the graded repair strategies.
A) No CSF leak and intact arachnoid. B) Grade 1 CSF leak (minor leak with no obvious
arachnoid defect). C) Moderate Grade 2 CSF leak, with a visible arachnoid defect. D) Large
grade 3 CSF leak, with large arachnoid and dural defects usually seen in the cases of extended
transsphenoidal procedures.

36. TURBINATE FLAP REPAIR

37. Post operative care:
 Broad spectrum antibiotics for 5 days.
 Patient is advised not to blow the nose for atleast 2- 3 weeks
post operatively.
 A lumber drain is to be kept on free drainage at the level of the
shoulders, and removed after 24 hours.
 Patient is slowly mobilised after 24 hours.

38. Key points:
 CSF leak cant be closed if not identified.
 Fluorescein should be used in all patients .
 Lumbar drain should be kept for 24 hours to
prevent any sudden increase in CSF pressure
from putting excessive pressure over the
repair.
 Introduction of fat has potential risk of
damage to the intracranial vasculature.
Introduction should be very gentle.
 Neurosurgical opinion is necessary
regarding any doubt about resection of the