Incidence of Intracranial Tuberculosis Abscess
Tuberculous brain abscess (TBA) is a rare manifestation of central nervous system tuberculosis, representing approximately 4% of CNS TB cases, with an even lower incidence among all extrapulmonary TB presentations.
Epidemiological Data
The incidence of intracranial TB abscess is notably low across multiple studies:
In specialized neurological centers, TBA accounts for only 4% of all CNS tuberculosis cases 1. This was demonstrated in a Mexican referral center where only 6 of 149 patients (4%) with CNS TB met diagnostic criteria for tuberculous brain abscess 1.
Among brain abscess cases in general, tuberculous etiology represents a small minority, with only 4 cases identified among 75 brain abscess specimens over a five-year period in one surgical series 2.
Genitourinary TB represented only 4.6% of extrapulmonary TB cases in the European Union between 1997 and 2017, indicating that tuberculous brain abscess is even less common 3, as it falls into an even rarer category of extrapulmonary manifestations.
Population-Specific Considerations
Endemic Areas
TBA occurs more frequently in developing countries and areas endemic for tuberculosis 4, where Mycobacterium tuberculosis remains an important causative pathogen of brain abscess 4.
The European Society of Clinical Microbiology and Infectious Diseases recommends sending pus samples for Ziehl-Neelsen stain, culture, and PCR for tuberculosis in endemic areas or based on clinical presentation 3.
Immunocompromised Patients
While TBA is traditionally associated with immunocompromised states, the majority of cases (75% in one series) actually occurred in immunocompetent patients 2. This challenges the assumption that TBA is primarily a disease of immunosuppression.
Nocardia species, fungi, and parasites are more common causes of brain abscess in severely immunocompromised patients, rather than tuberculosis 4.
Clinical Context and Risk Factors
Five of six patients (83%) in one series had a previous history of tuberculosis 1, suggesting that TBA often represents reactivation or progression of existing disease rather than primary infection.
TBA can develop despite ongoing antituberculous treatment, as documented in cases where patients developed brain abscesses while receiving treatment for pulmonary TB, lymph node TB, or TB meningitis 1, 5.
Three of six children in one pediatric series developed TBA despite 3 weeks to 12 months of antitubercular chemotherapy prescribed for post-TBM hydrocephalus 5.
Important Clinical Pitfalls
Multiloculated tuberculous brain abscesses represent a particularly high-risk presentation, as multiloculated lesions are recognized as a distinct risk factor for abscess rupture, which carries case-fatality rates of 27-50% 3.