Diagnostic features of tuberculous meningitis: a cross-sectional study

BACKGROUND: Tuberculous meningitis (TBM) is a common central nervous system infection in the Philippines; however it is difficult to diagnose as findings are non-specific. Hence we decided to determine if, among patients with chronic meningitis syndrome, the following are associated with the diagnosis: new-onset seizures; focal neurologic deficit; pulmonary tuberculosis (PTB) on chest X-ray; cerebrospinal fluid (CSF) pleocytosis with lymphocytic predominance; decreased CSF glucose; increased CSF protein. METHODS: Adult patients with suspected TBM were enrolled after informed consent was obtained. Baseline physical examination and diagnostic tests including CT scan of the head with contrast and CSF analysis for acid fast bacilli (AFB) smear, TB culture and cryptococcal antigen detection were done and results collected. Definite TBM was defined as positive AFB smear or positive TB culture or positive basal meningeal enhancement on CT contrast study. Logistic regression was done to determine which were associated with a diagnosis of TBM. RESULTS: 91 patients were included. Using the gold standard criteria mentioned above, 44 had definite TBM; but if subsequent clinical course and response to anti-Koch's therapy are considered, 68 had a final diagnosis of TBM. After logistic regression was performed, only abnormal CSF (the combination of CSF pleocytosis with lymphocytic predominance, decreased CSF glucose, and increased CSF protein) was associated with the diagnosis of TBM. CONCLUSION: In patients with chronic meningitis syndrome, only abnormal CSF was associated with the diagnosis of TBM.