Tuberculous Meningitis

Tuberculous meningitis is the most severe form of extrapulmonary TB and the leading cause of death in pediatric TB, usually occurring within 1 year of primary infection, especially at 3-6 months. Widespread BCG vaccination and TB control have reduced incidence. However, uneven control efforts leave the disease still common in some areas, with many cases diagnosed late. Understanding its development, early diagnosis, and rational treatment are crucial for reducing mortality and sequelae.

Common Symptoms

Coma; hematogenous dissemination of tubercle bacilli; neck stiffness; bulging fontanelle; irritability; low fever; opisthotonus; thready rapid pulse; convulsions

Causes and Pathogenesis

Tubercle bacilli enter lymph nodes and hematogenously seed the meninges and brain parenchyma including subependymal regions, replicating there. When host immunity declines or with aging, bacilli reactivate and rupture into the subarachnoid space, spreading with CSF over days to weeks. Tuberculous meningitis is often part of miliary TB: of 1180 cases at Beijing Children's Hospital (1964-1977), 44.2% had miliary pulmonary TB; pathology showed extrapulmonary TB in 94%, pulmonary TB in 93.4% (mostly miliary), hepatic/splenic miliary TB in ~62%, renal miliary TB in 41%, and intestinal/mesenteric TB in ~24%. Pathogenesis: Involvement of the meninges mainly occurs via the blood-CSF route and relates to high host allergy; it can also result from rupture of parenchymal or meningeal caseous foci, or direct spread from spinal, skull, or ear/mastoid TB. (1) M. tuberculosis is aerobic with a lipid-rich wall; it enters via the respiratory tract and initially forms small foci without enzymes or toxins causing asymptomatic infection. Weeks later, bacilli enter lymph nodes and hematogenously seed the meninges. When immunity develops, T cells sensitize macrophages that fuse into Langhans giant cells; most bacilli are killed, but a few persist within granulomas walled by incomplete capsule-like tissue, remaining dormant for years. When immunity declines, bacilli rupture into the subarachnoid space causing meningitis. Exudate accumulates in basal cisterns causing arachnoiditis; fibroblasts proliferate thickening meninges, causing communicating hydrocephalus, or obstruction of the fourth ventricle foramina causing obstructive hydrocephalus. (2) Pathology: Brain swelling, diffuse opacification of the pia, gray-yellow fibrinous exudate most prominent at basal cisterns; inflammatory exudate invades cranial nerve sheaths. Microscopy shows diffuse mononuclear/lymphocytic infiltration with scattered miliary tubercles composed of Langhans giant cells, monocytes, fibroblasts, and occasional plasma cells, often with caseous necrosis. Cerebral edema, occasional tuberculomas, ependymal/choroid plexitis, and arteritis progressing to thrombosis, infarction, or hemorrhage are seen. Hu Changheng et al. (1986) reported autopsy cases with massive intracerebral hemorrhage; chronic fibrotic thickening causes hydrocephalus. Ma Huaizhen and Li Wei (1988) found extrapulmonary TB in 62 of 65 autopsies, supporting tuberculous meningitis as a manifestation of systemic TB.

Treatment

Drug therapy, symptomatic treatment, supportive therapy

Preventive Measures

Main principles: build resistance, prevent respiratory transmission, manage and treat TB patients, immunize neonates and children, and provide early comprehensive treatment to reduce complications. The fundamental measure is preventing pediatric TB infection: 1. Ensure BCG primary and booster vaccination; effective BCG prevents or reduces tuberculous meningitis. Most affected children were unvaccinated. 2. Early detection and treatment of adult TB sources, especially among close contacts such as parents, nannies, and teachers. 3. Improve child resistance through proper feeding, reasonable routines, and immunization. 4. Early thorough treatment of pediatric primary TB; isoniazid chemoprophylaxis is practically meaningful for prevention.

Department to Visit

It is recommended to visit the Neurology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.