primary (spontaneous) and secondary; Gendeh et al. classified them into congenital, acquired, and spontaneous.
• The prevalence in various series varies from 3% to 36%.
• 75% of these leaks are associated with raised ICP
• 50% to 100% of these leaks have associated encephaloceles; likely due to the long-standing nature of these leaks
• The leaks are notoriously difficult to seal, and are associated with 25% to 87% recurrence rate.
• Herniation of intracranial contents through bony defects
• Meningocele involves herniation of dura only.
• Encephalocele (more accurately termed meningoencephalocele) involves herniation of dura and brain.
• Encephalocystocele involves herniation of dura, brain, and part of the ventricular system.
• A relatively larger skull base defect can cause CSF leaks with herniation of the above.
• These herniated materials are considered non-functioning, and are to be surgically removed prior to the repair of the skull base defect.
• Congenital encephaloceles: three subtypes
1. Occipital: most common; ~75% of cases
2. Sincipital (frontoethmoidal): ~15% of cases; nasofrontal (most common subtype), nasoethmoidal, nasoorbital
3. Basal: ~10% of cases; transethmoidal (most common subtype), sphenoethmoidal, transsphenoidal, sphenoorbital
• Patient often have few symptoms until a significant leak occurs.
• They may complain of clear, runny nasal discharge, which is often unilateral, commonly associated with headaches.
• This is increased when the patient bends over (reservoir sign) or increases his or her intracranial pressure with Valsalva-like maneuvers.
• The expansion of a nasal encephalocele with compression of the internal jugular vein or with crying/straining is known as Furstenberg’s sign; this is not present in gliomas or dermoids as there is no associated patent CSF tract.
• A central nervous system complication—for example, meningitis or intracranial abscess—may be the first presentation for some patients.
• Clinical: halo sign; only in traumatic injuries with mixed CSF and bloody rhinorrhea; a drop of the rhinorrhea will separate into two haloes (central ring of blood and an outer ring of CSF) on a filter paper
• Clinical: diagnostic endoscopy with maneuvers like bending forward and Valsalva
• Biochemical: presence of glucose (≥5 mg/dL); absent in nasal mucus
• Biochemical: β2 transferrin (sensitivity 99% and specificity 97%), a protein found in CSF, aqueous humour, and perilymphatic fluid, but not in blood or nasal secretions; the presence of cirrhosis or congenital protein anomalies increases false positive
• A newer assay, β trace protein appears very promising (in reports, sensitivity and specificity reaches 100%).
• High-resolution axial CT with coronal and sagittal reconstructions