Describe cerebrospinal fluid otorrhoea and encephalocele.

Cerebrospinal Fluid Otorrhoea

• CSF otorrhoea is leakage of cerebrospinal fluid from the ear, through a defect in the dura and the bone of the middle or posterior cranial fossa.
• Where the drum is intact, the fluid passes down the eustachian tube and appears as CSF rhinorrhoea instead.
• Causes — temporal bone fracture.
• The critical significance IS the risk OF meningitis.
• Features — clear, watery discharge from the ear or nose; increasing on straining, coughing, bending forward or Valsalva; a salty taste; positional headache; and conductive hearing loss where CSF fills the middle ear
• A clear effusion behind an intact drum after head injury should raise the possibility, and myringotomy releasing clear fluid confirms it
• Diagnosis:
• The halo (double-ring) sign — blood-stained fluid on tissue paper separates into a central red spot with a clear halo. It is suggestive but not reliable, since other fluids do the same
• Glucose testing — CSF contains glucose whereas nasal secretion does not; but it is unreliable because blood contamination gives false positives
• Beta-2 transferrin is the investigation of choice — it is found only in CSF, perilymph and aqueous humour, is highly sensitive and specific, and requires only a small sample. Beta-trace protein is an alternative
• Localisation — high-resolution CT for the bony defect; MRI cisternography, which is non-invasive and shows the CSF column; and CT cisternography with intrathecal contrast for a difficult case
• Management — conservative first for a traumatic leak, since the majority close spontaneously within 7 to 10 days: bed rest with the head elevated, avoidance of straining, nose-blowing and Valsalva, stool softeners, and a lumbar drain where it persists

Encephalocele and Meningoencephalocele

• An encephalocele is herniation of brain, and a meningocele of meninges, through a defect in the tegmen into the middle ear or mastoid
• Causes — previous mastoid surgery.
• The danger IS that IT looks like A polyp OR granulation tissue, and avulsing it tears brain and dura, causing a CSF leak, meningitis or worse. This is the practical reason the condition is taught
• Features suggesting it — a smooth, pale, pulsatile mass in the attic or a mastoid cavity.
• Never biopsy OR avulse A pulsatile mass IN the attic OR A mastoid cavity until it has been imaged
• Investigation — high-resolution CT showing the tegmen defect, and MRI.