Epidemiology India has one fifth of the world’s TB burden. 2 million new cases in 2009. Around 10% develop CNS disease.
Etiology Mycobacterium tuberculosis. Risk Factors: Delay in diagnosis and treatment HIV, Immunocompromised state.
Pathophysiology 50% cases : History present, Hematogenous spread Seed meninges or brain – Sub-pial/Sub-ependymal foci ofmetastatic caseous lesion – Rich Foci. Proximity to S.A Space determines type of CNS involvemeny. Rupture into S.A space – Meningitis Deep in parenchyma cause Tuberculoma or Abscesses.
Contd. Paresis of C.N nerves common as involvement more at base ofbrain. Disease evolves over 1-2 weeks. Thick gelatinous exudate infiltrates the cortical, meningeal bloodvessels, producing inflammation, obstruction, or infarction. Ultimate evolution to coma, with hydrocephalus and intracranialhypertension.
Management Initiate if high index of suspicion. Initial Therapy: Isoniazid – 300mg/d Rifampicin – 10mg/kg/d Pyrazinamide – 30mg/kg/d Ethambutol – 15-25 mg/kg/d Pyridoxine – 50mg/d Good Response : Discontinue Pyrazinamide after 2 months continueH & R for 6 – 12 months Inadequate Resolution : Continue for 9 – 12 months Dexamethasone in HIV –ve Patients. 12 -16mg/day for 3weeks, tapered over next 3 weeks
Contd. Obstructive hydrocephalus and neurological deterioration :ventricular drain or ventriculoperitoneal or ventriculoatrial shunt. Prevention: BCG Vaccine