Table Of Contents
TB Meningitis
CNS tuberculosis can occur as meningitis (the most common form), intracranial tuberculomas or spinal tuberculous arachnoiditis. It usually occurs following dissemination after primary infection (in children and young adults) or during reactivation as part of miliary TB.
The prevalence of CNS tuberculosis is high in regions with a high incidence of TB. It accounts for 1% of all cases of tuberculosis and 6% of all cases of extrapulmonary tuberculosis in immunocompetent individuals. 80% of TB meningitis occurs in patients with HIV infection.
If untreated, most patients with TB meningitis die within 5-8 weeks of the onset of illness.
Phases of TB Meningitis
| Phase | Description |
|---|---|
| Prodrome (2 – 3 weeks) | Gradual onset of malaise, lassitude, headache, low-grade fever and personality change |
| Meningitic phase | Pronounced neurologic features such as meningismus, protracted headache, vomiting, lethargy, confusion, cranial nerve and long-tract deficits and hydrocephalus |
| Paralytic phase | Illness accelerates rapidly leading to stupor and coma, seizures, and hemiparesis. |
- Pathophysiology
- Primary infection or latent reactivation of tuberculosis
- Bacillemia (Mycobacterium tuberculosis in blood) spreads to the central nervous system
- Scattered tuberculomas are established in the brain, meninges or adjacent skull/spine
- Proliferative arachnoiditis at the base of the brain (fibrous mass involving cranial nerves and other structures)
- CNS vasculitis leading to thrombosis and infarction commonly in the basal ganglia, cerebral cortex, pons and cerebellum
- Communicating hydrocephalus due to inflammation of the basilar cisterns which impairs CSF circulation and resorption. Tuberculomas and exudates may also obstruct outflow through the aqueducts.
- Signs and symptoms
- Headache
- Vomiting
- Confusion
- Lethargy
- Seizures
- Focal neurological deficits
- Personality change
- Coma
- Investigations
- CSF analysis + GeneXpert + Ziehl-Neelsen Stain and Mycobacteria Culture
- High opening pressure
- Clear but may form a fine clot (“spider-web”) if allowed to stand
- High WBCs (500 cells/mm3) predominantly lymphocytes
- Markedly elevated protein
- Low glucose
- CT Scan or MRI
- Basilar meningeal enhancement
- Tuberculoma (space occupying lesion)
- Hydrocephalus (ventricular enlargments)
- CSF analysis + GeneXpert + Ziehl-Neelsen Stain and Mycobacteria Culture
- Treatment
- RHZE for 9 – 12 months for drug sensitive
- Intensive phase with RHZE for 2 months
- Continuation phase with RH for 7 – 10 months
- RHE for 18 months (when pyrazinamide is omitted or cannot be tolerated)
- Corticosteroids: dexamethasone ****or prednisone ****for 6-8 weeks: reduces the rates of complications
- Ventriculoperitoneal shunt for hydrocephalus or raised ICP
- RHZE for 9 – 12 months for drug sensitive
