What are the stages and treatment of tubercular meningitis?

Stages and Treatment of Tuberculous Meningitis

Tuberculous meningitis (TBM) is classified into three stages based on clinical severity, with treatment requiring a prolonged antitubercular regimen plus adjunctive corticosteroids for stages II and III to reduce mortality.

Clinical Staging of Tuberculous Meningitis

The British Medical Research Council staging system is used to classify TBM severity:

• Stage I (Mild): Patients are fully conscious, rational, and without neurological deficits
• Stage II (Moderate): Patients present with confusion or neurological signs such as cranial nerve palsies or hemiparesis
• Stage III (Severe): Patients are comatose or stuporous with severe neurological signs

Treatment Approach

Antitubercular Therapy

1. Standard Regimen:

   • Duration: 12 months total for TBM 1, 2
   • Intensive Phase (first 2 months): Isoniazid, Rifampin, Pyrazinamide, and a fourth drug (Ethambutol or Streptomycin)
   • Continuation Phase (next 10 months): Isoniazid and Rifampin

2. Medication Considerations:

   • Isoniazid, pyrazinamide, and prothionamide/ethionamide penetrate well into CSF 1
   • Rifampin penetrates less well into CSF 1
   • Streptomycin and ethambutol only penetrate adequately when meninges are inflamed early in treatment 1
   • Ethambutol should be used with caution in unconscious patients (Stage III) as visual acuity cannot be tested 1

Adjunctive Corticosteroid Therapy

• Strong recommendation for adjunctive corticosteroid therapy in TBM 1, 2
• Reduces mortality by approximately 25% 2
• Recommended regimens:
  • Dexamethasone: 12 mg/day, tapered over 6-8 weeks 2
  • Alternative: Prednisolone 60 mg/day, tapered over 6-8 weeks 2
• Particularly indicated for more severe disease (Stages II and III) 1, 3

Management of Complications

1. Hydrocephalus:

   • Occurs in approximately 65-82% of TBM patients 4, 5
   • May require neurosurgical intervention (ventriculoperitoneal shunting) 1, 3
   • Early-stage hydrocephalus may resolve with medical therapy alone 5

2. Other complications requiring neurosurgical referral:

   • Tuberculous cerebral abscess
   • Paraparesis 1

Prognostic Factors

Poor prognostic factors include:

• Advanced stage of disease at presentation 4, 6
• Presence of hydrocephalus 6, 5
• Presence of basal exudates 5
• Cranial nerve palsies 5
• Visual impairment 5
• Cerebral infarctions 4

Treatment Algorithm

1. Initial Assessment:

   • Determine clinical stage (I, II, or III)
   • Perform neuroimaging to assess for hydrocephalus, infarctions, tuberculomas
   • Analyze CSF (expect lymphocytic pleocytosis, elevated protein, low glucose)

2. Initiate Treatment:

   • Start antitubercular therapy immediately upon clinical suspicion
   • Include 4 drugs initially: Isoniazid, Rifampin, Pyrazinamide, and Ethambutol/Streptomycin
   • Add corticosteroids for all patients, especially critical for Stage II and III

3. Duration:

   • Continue Isoniazid and Rifampin for 12 months
   • Pyrazinamide and fourth drug for first 2 months
   • Taper corticosteroids over 6-8 weeks

4. Monitoring:

   • Regular neurological assessment
   • Follow-up neuroimaging to assess for hydrocephalus resolution
   • Monitor for drug adverse effects

Special Considerations

• HIV co-infection: May require longer treatment duration and careful monitoring for drug interactions 7
• Drug resistance: If suspected, consult TB experts and ensure at least two effective drugs are included in the regimen 3
• Pregnancy: Avoid streptomycin (risk of congenital deafness) and consider risks of pyrazinamide 8

Early diagnosis and prompt initiation of appropriate treatment are critical for improving outcomes in TBM, as mortality and severe sequelae remain high despite optimal therapy.