The Role of Whole-body CT and MRI Imaging to Aid a Diagnosis of Tuberculous Meningitis in a Low Incidence Setting

Abstract

Background Tuberculous meningitis (TBM) is difficult to diagnose in view of its non-specific signs and symptoms and low accuracy of tests to diagnose TBM. Patients with TBM often have coexisting pulmonary or other extra-pulmonary sites of infection and as a result clinical scoring systems have included radiological tests outside the CNS to aid diagnosis (Lancet scoring system). Methods We conducted a retrospective observational study of all consecutive patients with probable TBM diagnosed between 2017 and 2021 at a large East London Hospital to investigate the use of imaging including CT chest, abdomen, and pelvis (CT CAP) and MRI brain to aid to a diagnosis of TBM. Results We included 48 cases with a probable diagnosis of TBM. Sixty-five percent were male. Median age was 37 years (IQR 20.5). Twenty-one patients were migrants, ten patients were UK born. Median CSF WCC was 43/mm3 (149.5/mm3) , median CSF lymphocyte count was 70% (IQR 45%), median CSF protein count was 1353mg/l (IQR 1113mg/L) and median CSF glucose count was 2.9mmol/L (IQR 1.6mmol/L). Twenty-five patients had a MRI brain showing meningeal enhancement (52%), tuberculomas (58%), infarcts (13%) and hydrocephalus (15%). Five patients had a positive CSF culture for TB and three patients had a positive TB PCR in CSF. Seven patients had a normal MRI brain. Thirty-eight patients had a CT CAP, as the result of CT CAP these patients had further investigations confirming a diagnosis of TB including bronchoscopy / BAL, EBUS, pleural aspiration, sputum culture, brain biopsy, lymph node biopsy, abscess aspiration/culture, urine culture, bone marrow biopsy and colonic/peritoneal biopsy. Conclusion Whole body CT and MRI brain is useful in confirming a diagnosis of TBM in a low incidence TB setting. Patients with TBM often have concomitant pulmonary TB or TB in other extra pulmonary sites which can aid diagnosis.