Tuberculous meningitis — DTM&H MCQ

Correct answer: C — Tuberculous meningitis

The correct answer is C, tuberculous meningitis. The subacute (three week) history of headache, fever and confusion with a CSF profile of lymphocytic pleocytosis, high protein and low glucose is the classic triad for tuberculous meningitis, and basal exudate causing raised intracranial pressure commonly entraps the long intracranial course of the sixth cranial nerve, producing the false localising VI palsy described. India has a high tuberculosis burden, making TB the most likely cause of this picture. NICE guidance stresses starting anti-TB therapy plus corticosteroids on clinical and CSF suspicion because confirmatory smear, culture and PCR are often negative despite true disease. The gradual, weeks long evolution and specific biochemical CSF pattern together point away from the alternatives. Why the other options are wrong: B. Cryptococcal meningitis: occurs mainly in immunocompromised (especially HIV positive) patients; nothing in the stem suggests immunosuppression, and basal exudate causing cranial nerve palsy is far more characteristic of TB. A. Japanese encephalitis: causes an acute encephalitic illness over days with CSF lymphocytosis but normal glucose and only mildly raised protein, not the low glucose seen here. E. Cerebral malaria: presents acutely over hours to a few days with fever and altered consciousness, but CSF is usually normal or mildly raised protein with normal glucose and no significant pleocytosis. D. Typhoid encephalopathy: occurs with systemic enteric fever features (relative bradycardia, abdominal symptoms), and CSF is typically normal, not showing this lymphocytic, low glucose, high protein pattern. Key point: subacute meningitis with lymphocytic CSF, low glucose, high protein and a cranial nerve palsy (especially VI) in someone from a TB endemic country is tuberculous meningitis until proven otherwise, and treatment should not await microbiological confirmation.

Reference: NICE. Tuberculosis. NICE guideline NG33 (2016, updated 2024), section 1.3.7 on CNS TB diagnosis and adjunctive corticosteroids. https://www.nice.org.uk/guidance/ng33