Metronidazole Induced Encephalopathy: A Case Report Showing Devastating Course on Consecutive MR Imaging

Metronidazole-induced encephalopathy is a rare neurologic adverse effect of an antibiotic drug ‘metronidazole’. Although it is usually reversible with immediate cessation of the drug, it can also be fatal when used continuously. Here, we present a 72- year-old female who was on metronidazole for a total of 46 consecutive days. Her initial MRI on the 22nd day of medication use revealed a typical involvement of the cerebellar dentate nuclei, corpus callosum splenium, and periaqueductal midbrain, suggesting metronidazole-induced encephalopathy. However, she continued the medication for another 24 days, until she revisited our emergency department with mental status change. Her consecutive MRI showed diffuse cerebral and brainstem involvement, as well as a more prominent involvement of the dentate nuclei and splenium. We present this case to highlight that it is possible for metronidazole-induced toxic encephalopathy to worsen without immediate withdrawal of the offending drug.