Tubercular Meningitis: TB of the Brain — The Most Dangerous Form of Tuberculosis

Tubercular meningitis (TBM) — Mycobacterium tuberculosis infecting the meninges and CSF — is a medical emergency with a mortality of 20–30% even with treatment, and significant neurological disability in up to 50% of survivors. India bears the world's highest burden of tuberculosis, and TBM is not uncommon in Hyderabad and Telangana. Its clinical presentation is insidious and subacute — very different from the acute presentation of bacterial meningitis — making early diagnosis challenging and delays common.

Subacute Presentation — The Diagnostic Challenge

TBM typically evolves over 1–4 weeks (not hours like bacterial meningitis): prodrome of fever, malaise, anorexia, and weight loss; gradually worsening headache; meningismus (neck stiffness) developing over days; cranial nerve palsies (sixth nerve palsy — diplopia; third nerve palsy — ptosis and large pupil — from basal exudate involving the cranial nerves at the base of the brain); progressive drowsiness; seizures. Hydrocephalus — from blockage of CSF pathways by inflammatory exudate — is a common complication causing worsening consciousness.

Diagnosis

LP findings in TBM: lymphocytic pleocytosis (100–500 cells); high protein (100–500mg/dL — very high, sometimes forming a pellicle); low glucose (CSF:serum glucose ratio below 0.5); AFB smear: low sensitivity (10–40%) — repeat on 3 consecutive LPs to improve yield; CSF culture: gold standard but takes 6–8 weeks; GeneXpert MTB/RIF Ultra: rapid PCR — sensitivity 70–90% in TBM; adenosine deaminase (ADA): elevated. MRI brain with gadolinium: basal meningeal enhancement (enhancement around the brainstem); hydrocephalus; cerebral infarcts (from vasculitis of the blood vessels running through the infected meninges).

Treatment

Standard anti-tubercular therapy (HRZE — isoniazid + rifampicin + pyrazinamide + ethambutol) for 2 months, followed by HR for 7–10 months (12 months total). Adjuvant dexamethasone (corticosteroids) reduces mortality and disability. Manage hydrocephalus with ventriculoperitoneal shunting if necessary. Sri Anand CNC, Chanda Nagar, Hyderabad. Call +91 90633 66983.