Temporal lobe encephalitis need not always be herpes simplex encephalitis: Think of tuberculosis

Historically, temporal lobe encephalitis is considered as a pathognomonic feature of Herpes simplex encephalitis. This rule may not always be true and we believe that clinicians should keep their differential open. We here report once such. Case of a 36-year-old Indian male who developed altered sensorium following a prodrome of headache and fever. Examination and imaging suggested Temporal Lobe Encephalitis (TLE). Herpes encephalitis was considered and he was started on anti-virals awaiting lumbar puncture reports. Cerebrospinal fluid (CSF) analysis for Herpes Polymerase Chain Reaction (PCR) turned out to be negative. Later, to our surprise PCR for tuberculosis (TB) was positive. CSF was 100% lymphocytic and Adenosine deaminase was 12. He was started on 5 drug anti-tuberculosis regimen following which he showed a significant clinical improvement. Given the prevalence of tuberculosis in the sub-continent, clinicians must be aware of this diagnostic possibility when a patient with TLE does not respond to anti-virals. Apart from disease specific therapy, multi-disciplinary approach involving speech therapy is warranted. An early aetiological characterization of TLE has both diagnostic and prognostic implications, failing which patient may succumb.