Tuberculous meningitis

Definition

• Meningeal infection by Mycobacterium tuberculosis

Classification

• Stage 1: normal level of consciousness, no focal neurological deficits
• Stage 2: decreased level of counsciousness, significant focal neurological deficits
• Stage 3: seizures, comatose

Epidemiology

• About 1% of TB cases in Canada

Differential Diagnosis

• Fungal meningitis
• Sarcoidosis
• Neoplasm

Risk Factors

• Young
• Female
• Originally from endemic country
• Previous TB

Presentation

History

• Prodrome (1-3 weeks)
  • Personality changes
  • Low-grade fever
  • Malaise
  • Weight loss
  • Gradual onset of worsening headache
• Headache
• Fevers
• Vomiting
• Confusion
• Personality changes
• Photophobia (only 5-10%)
• Seizures

Physical Exam

• Meningeal symptoms
• Fevers
• Vomiting
• Meningismus
• Focal neurological deficits
  • Cranial nerve palsies in VI, III, and IV
  • Hemiplegia, paraplegia
  • Urinary retention
• Confusion, coma

Investigations

• Lumbar puncture
  • Increased lymphocytes, decreased glucose, and increased protein
  • Need 3-5mL of CSF for culture
  • May need serial LPs
• CT head

Management

• Rule out neoplasm and fungus, then start empiric treatment
• HIV test (delay antiretrovirals by 8 weeks, though)
• Standard HREZ x2mo then HR x7-10mo
  • Can replace ethambutol with a fluoroquinolone
• Dexamethasone 3mg po qid x2wk then taper over 6-8wks
  • High risk of IRIS

Prognosis

• Depends on stage at presentation
• Mortality is high
  • Stage 1: 10-20%
  • Stage 2: 20-40%
  • Stage 3: 60%
• Morbidity is high, with about 20% of patient being left with significant neurological sequelae
  • Mental retardation
  • Psychiatric disorders
  • Seizures
  • Blindness
  • Deafness
  • Ophthalmoplegia
  • Hemiparesis