Wilkinson RJ, Rohlwink U, Misra UK, et al. Tuberculous meningitis. Nat Rev Neurol. 2017;13(10):581-598. doi:10.1038/nrneurol.2017.120.
Tuberculosis remains a global health problem, with an estimated 10.4 million cases and 1.8 million deaths resulting from the disease in 2015. The most lethal and disabling form of tuberculosis is tuberculous meningitis, for which more than 100,000 new cases are estimated to occur per year. In adults, the best-documented risk factor for tuberculous meningitis is HIV‑1 co‑infection. Among HIV-infected individuals who live in areas where tuberculosis is highly endemic, the proportion of HIV‑1‑associated meningitis cases attributable to Mycobacterium tuberculosis can exceed 50%. Individuals with tuberculous meningitis and a HIV‑1 co‑infection have a twofold to threefold increase in relative risk of death from any cause with overall mortality around 40%, even in those individuals prescribed antiretroviral therapy. Drug-resistant tuberculous meningitis in people co‑infected with HIV‑1 has a particularly poor prognosis, approaching 100% mortality.
Bacterial replication must occur in the CNS for tuberculous meningitis pathogenesis to proceed. However, the bacillary load in the CSF rarely exceeds 100–1000 bacterial colonies per milliliter, and viable bacilli are difficult to detect in the majority of individuals. Early studies in experimental animal models showed that the meningitis syndrome and even death of tuberculin-sensitized animals could be induced by meningeal inoculation with dead bacilli. Much of the tissue damage is therefore attributed to a dysregulated host inflammatory response. Once bacilli have traversed the blood–brain barrier, they are taken up by microglia and can also replicate in these cells, leading to the induction of microglial cytokine and chemokine production.
The importance of infarction to long-term outcomes has led to interest in cranial vessel imaging. CTA has been used to define lesions in the anterior and posterior cerebral circulation, and has demonstrated that the supraclinoid portion of the internal carotid artery …