Table 1 Diagnostic criteria for classification of definite, probable, possible, and not tuberculous meningitis⁴

 Symptom duration > 5 days

4

 Systemic symptoms suggestive of TB (one or more of the following): weight loss (or poor weight gain in children), night sweats, or persistent cough > 2 weeks

2

 History of recent (within past year) close contact with an individual with pulmonary TB or a positive TST or IGRA (only in children <10 years of age)

2

 Focal neurological deficit (excluding cranial nerve palsies)

1

 Cranial nerve palsy

1

 Altered consciousness

1

 Clear appearance

1

 Cells: 10–500 per μl

1

 Lymphocytic predominance (>50 %)

1

 Protein concentration > 1 g/L

1

 CSF to plasma glucose ratio < 50 % or an absolute CSF glucose concentration < 2.2 mmol/L

1

 Hydrocephalus

1

 Basal meningeal enhancement

2

 Tuberculoma

2

 Infarct

1

 Pre-contrast basal hyperdensity

2

 Evidence of TB elsewhere

(Maximum category score = 4)

 Chest radiograph suggestive of active TB: signs of TB = 2; miliary TB = 4

2/4

 CT/ MRI/ ultrasound evidence for TB outside the CNS

2

 AFB identified or M.tuberculosis cultured from another source—ie, sputum, lymph node, gastric washing, urine, blood culture

4

 Positive commercial M.tuberculosis TB NAAT from extra-neural specimen

4