Table 1. Case definitions used in establishing a TBM diagnosis.

Category	Criterion
(a) Clinical meningitis criteria	Neurological symptoms such as altered consciousness, sensation or strength, seizure or dysphasia with one or more of the following: fever, headache, neck rigidity, CSF pleocytosis (> 5 leukocytes/μl), or brain imaging suggestive of meningitis
(b) Tuberculous meningitis CSF characteristics	Protein >40 mg/dl Glucose <40 mg/dl Leukocytes >5 white blood cells /μl ADA > 9 U/L
(c) Tuberculous meningitis definitions
(c.1) Not TBM	Alternative diagnosis established, without a laboratory proven diagnosis of tuberculous meningitis from the CSF.
(c.2) TBM diagnosis	Clinical suspicion (e.g. prior TB history, cerebral imaging results) combined with abnormal CSF consistent with TBM and exclusion of other potential etiologies, causing the patient’s clinician to commence treatment for TBM.
(c.2.1) Definite TBM	Either AFB seen in the CSF smear; or M. tuberculosis cultured from the CSF; or a CSF positive GeneXpert MTB/RIF result.
(c.2.2) Probable TBM*	No AFB seen in the CSF smear; no M. tuberculosis cultured from the CSF; no CSF positive GeneXpert MTB/RIF result. May also have a positive M. tuberculosis smear and/or culture or PCR result from samples taken outside the CNS. PLUS ≥ 10 points on the diagnostic criteria scale (when cerebral imaging is not available) or ≥12 points (when cerebral imaging is available) with at least two points coming from either CSF or cerebral imaging criteria
(c.2.3) Possible TBM*	No AFB seen in the CSF smear; no M. tuberculosis cultured from the CSF; no CSF positive GeneXpert MTB/RIF result. May also have a positive M. tuberculosis smear and/or culture or PCR result from samples taken outside the CNS. PLUS A score of 6–9 points (when cerebral imaging is not available) or 6–11 points (when cerebral imaging is available)

*follows the scoring system based on the consensus uniform clinical case definition found in Marais et al [4].