TB Meningitis 101

This past week we discussed about TB meningitis at Morning Report. Below are some key points about this disease and its management:

Diagnosis and Presentation

  • Occurs when subependymal or subpial tubercles, also known as “Rich foci” seeded during bacillemia of primary infection or disseminated disease, rupture into the subarachnoid space
  • Risk factors include travel to or residence in a country with high TB prevalence, elderly, alcoholism, HIV, drug abuse
  • Presentation may be subacute or chronic as symptoms are variable and non-specific: unrelenting headache (28%), fever (13%), lethargy, confusion, seizures
  • 25% of patients present with cranial nerve VI palsy (diplopia and medial strabismus)
  • Hyponatremia due to SIADH is common
  • Characteristic CSF findings: lymph-predominant pleiocytosis, elevated protein levels (100-500mg/dL), low glucose (<45mg/dL) or CSF:plasma ratio < 0.5, high opening pressure
  • CSF samples sent for multiple tests increase sensitivity (smear, culture, PCR, adenosine deaminase)

Imaging

  • CXR: pulmonary TB seen in 25-55% of adults
  • MRI/CT: may show leptominengeal enhancement, hydrocephalus, tuberculoma, or infarcts

Treatment

  • RIPE: If sensitive to isoniazid and rifampin, can narrow down to I+R after 2 months. Duration of 9-12 months.
  • Steroids recommended for more severe disease: 12mg/day of dexamethasone for 3 weeks then taper for a total length of 6 weeks

References:

1. Marx, et al. Tuber Res and Treat. 2011

2. Johns Hopkins ABX Guide