Tuberculous MeningitisSANJAY GEORGE

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 of metastatic 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 of brain.

Disease evolves over 1-2 weeks.

Thick gelatinous exudate infiltrates the cortical, meningeal blood vessels, producing inflammation, obstruction, or infarction.

Ultimate evolution to coma, with hydrocephalus and intracranial hypertension.

Clinical Features

Headache

Vomiting

Low Grade Fever

Malaise, Anorexia, Irritability

Severe Headache

Confusion

Lethargy

Altered Sensorium

Neck Rigidity

Initially

Late

Signs

Meningism (maybe absent)

Occulomotor palsies

Papilloedema

Depression of conscious level

Focal hemisphere signs.

Differential Diagnosis

Other Infectious causes of meningitis

Acute hemorrhagic leukoencephalopathy

Behçet disease

Chemical meningitis

Chronic benign lymphocytic meningitis

Neoplastic: metastatic, lymphoma

Systemic lupus erythematosus

Vascular: Multiple emboli, subacute bacterial endocarditis, sinus thrombosis

Vasculitis

Vogt-Koyanagi-Harada syndrome

Investigations

Lumbar Puncture: High leucocyte count (upto 1000/μL) with lymphocytic predominance.

Elevated Protein (100-800 mg/dL).

Mildly Decreased Glucose Concentration (20 – 40 mg/dL)

AFB – 1/3rd cases

CSF culture (Gold Standard) – diagnostic in 80% cases.

PCR

Imaging Studies – MRI, CT

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 continue H & R for 6 – 12 months

Inadequate Resolution : Continue for 9 – 12 months

Dexamethasone in HIV –ve Patients. 12 -16mg/day for 3 weeks, tapered over next 3 weeks

Contd.

 Obstructive hydrocephalus and neurological deterioration : ventricular drain or ventriculoperitoneal or ventriculoatrial shunt.

Prevention: BCG Vaccine

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