Description

• A granulomatous infection of the brain, meninges, or spinal cord caused by Mycobacterium tuberculosis
• Central nervous system tuberculosis (CNS TB) includes tuberculous meningitis, intracranial or spinal tuberculoma, and spinal tuberculous arachnoiditis.

Epidemiology

Incidence

• 2.8 cases of TB per 100,000 in United States
• CNS TB accounts for 1% of all active TB cases but is more debilitating than other types of TB.

Prevalence
In 2017, 10 million cases of active TB with 1.3 million TB-related deaths worldwide (CDC)

Etiology and Pathophysiology

M. tuberculosis: History of TB is elicited in only 10% of infected adults.

• Spreads hematogenously to the CNS, generally from a pulmonary focus
• Small areas of infection (Rich foci) form in the brain parenchyma. Meningitis occurs when Rich foci rupture into subarachnoid space.

Genetics
Host factors that influence the risk of infection are polymorphisms associated with the LTA4H gene (1).

Risk Factors

• Very young and very old, HIV infection, solid organ transplant patients, diabetics, patients on steroids or other immunosuppressive therapies
• History of pulmonary TB or exposure to active TB
• Malnutrition, recent measles (children), alcoholism, malignancy
• Latent TB infection
• Immigrants from TB-endemic areas

General Prevention

• Direct-observed antituberculous therapy improves treatment success and minimizes drug resistance.
• Neonatal and childhood bacillus Calmette-Guérin (BCG) vaccination in areas with high incidence of TB disease recommended to protect against TB meningitis (2)

Commonly Associated Conditions

HIV infection; alcohol abuse; malignancy