A patient with CSOM develops headache, vomiting, bilateral papilloedema and a lucid but drowsy state. CT head shows no mass lesion, no hydrocephalus, and a filling defect in the right sigmoid sinus. The pathogenetic basis of this presentation is:

• A Vasospasm of the anterior cerebral artery
• B Direct extension of infection into the fourth ventricle
• C Obstruction of cerebrospinal fluid absorption due to impaired venous drainage through the thrombosed lateral sinus ✓
• D Obstruction of the aqueduct of Sylvius by periaqueductal oedema

Explanation

This is otitic hydrocephalus, a recognised sequela of lateral sinus thrombosis. Thrombosis of the dominant lateral sinus impedes venous outflow from the brain, which reduces cerebrospinal fluid absorption across the arachnoid villi and raises intracranial pressure diffusely, producing papilloedema without focal signs, ventricular dilatation or a mass lesion. Aqueductal obstruction would produce obstructive hydrocephalus visible on CT, which is explicitly absent here.

Reference: Dhingra, Diseases of Ear, Nose and Throat, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.