Metronidazole-induced encephalopathy: case report and review of MRI findings.

A 74-year-old man presented with a four week history of behavioural disturbances, upper and lower extremity numbness and impaired balance. He had been treated with metronidazole for six months for osteomyelitis of the right hallux. Examination revealed encephalopathy, and glove-and-stocking sensory loss to pinprick with reduced vibration threshold at the toe. The gait was wide based and ataxic. Nerve conduction studies showed a large fibre sensory-motor axonal polyneuropathy. Magnetic resonance imaging (MRI) revealed a solitary restricted diffusion lesion in the splenium of the corpus callosum (Figure A, B) with subtle prolongation of T2 (Figure C). The radiographic differential diagnosis included hypoglycaemia, viral encephalitis, antiepileptic drug toxicity/withdrawal and metronidazole toxicity1. The combination of the imaging finding with the history of prolonged metronidazole use suggested metronidazole induced encephalopathy. Metronidazole was discontinued based