What are the typical presentation and treatment of tubercular meningitis?

Tuberculous Meningitis: Presentation and Treatment

Tuberculous meningitis (TBM) is a potentially devastating disease with high morbidity and mortality that requires early recognition and prompt treatment with a standard four-drug regimen plus adjunctive corticosteroids to improve outcomes. 1

Clinical Presentation

Initial Phase (Prodromal)

• Subacute onset with symptoms persisting for 2-3 weeks before diagnosis 2, 3
• Early nonspecific symptoms:
  • Malaise
  • Fever
  • Headache (often severe and persistent)
  • Personality changes
  • Fatigue

Progressive Phase

• Meningeal signs develop:
  • Neck stiffness (meningismus)
  • Positive Kernig's and Brudzinski's signs
  • Vomiting
  • Photophobia 4
• Neurological deterioration:
  • Altered mental status (confusion progressing to drowsiness)
  • Cranial nerve palsies (especially VI nerve) 4
  • Focal neurological deficits
  • Seizures
  • Visual impairment (can be irreversible if diagnosis is delayed) 5

Advanced Phase

• Severe neurological impairment:
  • Stupor or coma
  • Hydrocephalus
  • Stroke-like symptoms 3
  • Increased intracranial pressure 4

Diagnostic Approach

CSF Analysis

• Characteristic findings:
  • Lymphocytic-predominant pleocytosis
  • Elevated protein levels
  • Low glucose levels 2, 4
• Acid-fast bacilli (AFB) smear and culture have low sensitivity but increased yield with multiple, large-volume samples 2
• PCR testing has high specificity but suboptimal sensitivity 2

Imaging

• CT scan findings highly suggestive of TBM:
  • Basilar meningeal enhancement
  • Hydrocephalus (any degree)
  • Tuberculomas may be present 6

Treatment

Antituberculous Therapy

• Treatment should be initiated immediately upon clinical suspicion, even before diagnostic confirmation 7, 2
• Initial phase (2 months):
  • Isoniazid (INH)
  • Rifampin (RIF)
  • Pyrazinamide (PZA)
  • Ethambutol (EMB) 7, 1
• Continuation phase (7-10 months):
  • INH and RIF 7, 1
• Parenteral forms available for patients with altered mental status 7
• Treatment duration may need extension up to 18 months for severe cases or slow responders 1

Adjunctive Corticosteroid Therapy

• Recommended for all TBM patients, particularly those with decreased level of consciousness 7, 1
• Dexamethasone regimen:
  • Adults: 12 mg/day
  • Children <25 kg: 8 mg/day
  • Initial treatment for 3 weeks, then tapered over the following 3 weeks 7, 1

Monitoring

• Repeated lumbar punctures to monitor CSF changes (cell count, glucose, protein) 7
• Serial CT scans to evaluate hydrocephalus and tuberculoma response 6
• Monitor for steroid-related adverse effects 1

Special Considerations

Staging and Prognosis

• British Medical Research Council staging system:
  • Stage I: Alert and oriented with no focal neurological deficits
  • Stage II: Lethargy or behavioral changes, minor neurological deficits
  • Stage III: Stupor or coma, severe neurological deficits 1
• Prognosis directly related to stage at treatment initiation 1, 6

Complications Management

• Hydrocephalus may require surgical shunting, especially with symptoms of raised intracranial pressure 6
• Tuberculomas are best treated medically, often with adjunctive corticosteroids 6
• Visual impairment may be irreversible if diagnosis and treatment are delayed 5

HIV Co-infection

• HIV patients have increased risk of developing TBM
• Clinical features and outcomes similar to non-HIV patients 7

Key Pitfalls to Avoid

• Delaying treatment while awaiting diagnostic confirmation - this significantly worsens outcomes 7, 5
• Failing to consider TBM in patients with subacute meningitis, especially those from endemic regions 4
• Discontinuing corticosteroids too quickly, which may lead to clinical deterioration 1
• Inadequate monitoring for complications like hydrocephalus and tuberculomas 6