Tuberculosis meningitis
Definition: Tuberculous meningitis is a chronic/subacute infection of the meninges caused by Mycobacterium tuberculosis, usually resulting from hematogenous spread from a primary focus (lungs most common).
Pathogenesis
- Primary TB infection → dissemination
- Formation of Rich foci in brain/meninges
- Rupture into subarachnoid space → intense inflammatory response
- Basal exudates → cranial nerve involvement + hydrocephalus
Clinical Stages
Stage I (Prodromal stage): Low-grade fever.Malaise, fatigue. Headache. Behavioral changes
Stage II (Meningitic stage): Severe headache. Neck stiffness. Vomiting. Cranial nerve palsies (especially VI → diplopia). Mild confusion
Stage III (Advanced stage): Altered consciousness → coma. Seizures. Focal neurological deficits. Severe hydrocephalus
Meningeal Syndrome in TB Meningitis: Neck stiffness. Kernig sign positive. Brudzinski sign positive. Subacute onset (important distinction from bacterial meningitis)
CSF Findings
- Typical TB CSF Pattern: ↑ Opening pressure. Clear or slightly cloudy CSF. ↑ Lymphocytes (lymphocytic pleocytosis). ↑↑ Protein (very high). ↓ Glucose
- Additional findings:
- Fibrin web formation (“cobweb clot” on standing)
- Positive Ziehl-Neelsen stain (low sensitivity)
- PCR for TB (more sensitive)
Neuroimaging Findings (supportive): Basal meningeal enhancement. Hydrocephalus. Tuberculomas. Infarcts (vasculitis of small vessels)
Complications: Hydrocephalus (common).Cranial nerve palsies (III, VI, VII). Cerebral infarctions. Seizures. Cognitive impairment. Death if untreated
Differential Diagnosis
1. Bacterial meningitis: Acute onset. Neutrophils in CSF. Very rapid deterioration
2. Viral meningitis: Mild course. Normal glucose
3. Fungal meningitis: Similar CSF but immunocompromised host
4. Brain tumor: No infection signs. Focal deficits, mass effect
Treatment : Anti-TB therapy (long duration). Isoniazid. Rifampicin. Pyrazinamide. Ethambutol
Adjunct therapy
- Corticosteroids (reduce inflammation and mortality)
- Management of hydrocephalus (shunt if needed)
Prognosis: Depends on stage at diagnosis
Stage I → good recovery possible
Stage II → variable outcome
Stage III → high mortality and severe deficits