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For further information, see CMDT Part 35-36: Tuberculous Meningitis

KEY FEATURES

Essentials of Diagnosis

  • Gradual onset of listlessness and anorexia

  • Fever, headache, vomiting, and seizures common

  • Cranial nerve abnormalities typical

  • Tuberculous focus may be evident elsewhere

  • Cerebrospinal fluid shows several hundred lymphocytes per microliter, low glucose, and high protein

General Considerations

  • Caused by rupture of a meningeal tuberculoma resulting from earlier hematogenous seeding of tubercle bacilli from a pulmonary focus, or may be a consequence of miliary spread

CLINICAL FINDINGS

Symptoms and Signs

  • Onset usually gradual

    • With listlessness, irritability, anorexia, and fever

    • Followed by headache, vomiting, convulsions, and coma

  • In older patients, headache and behavioral changes are prominent early symptoms

  • Nuchal rigidity and cranial nerve palsies occur as the meningitis progresses

  • Evidence of active tuberculosis elsewhere or a history of prior tuberculosis is present

Differential Diagnosis

  • Fungal and other granulomatous meningitides

  • Syphilis

  • Carcinomatous meningitis

  • Tuberculous meningitis may be confused with any other type of meningitis, but the gradual onset, the predominantly lymphocytic pleocytosis of the spinal fluid, and evidence of tuberculosis elsewhere often point to the diagnosis

DIAGNOSIS

Laboratory Tests

  • The spinal fluid is frequently yellowish, with increased pressure, 100–500 cells/mcL (0.1–0.5 × 109/L) (predominantly lymphocytes, though neutrophils may be present early during infection), increased protein, and decreased glucose (Table 32–2)

  • Acid-fast stains of cerebrospinal fluid usually are negative, and cultures also may be negative (sensitivity less than 50%)

  • Nucleic acid amplification tests allow for rapid diagnosis, when positive

  • The tuberculin skin testing and interferon-gamma release assays do not distinguish between active and latent tuberculosis and may be negative in the presence of CNS infection

Table 32–2.Typical CSF findings in various CNS diseases (listed in alphabetical order after Normal).

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