Reversible Metronidazole-Induced Encephalopathy With Typical MRI Features Following a Low Cumulative Dose: Case...

Metronidazole-induced encephalopathy (MIE) is an under-recognised but potentially reversible neurotoxic complication of metronidazole therapy, typically associated with high cumulative doses or underlying comorbidities such as hepatic dysfunction. Classic MRI findings include symmetric T2/FLAIR hyperintensities in the cerebellar dentate nuclei, brainstem, and splenium of the corpus callosum.

We report a 64-year-old woman with well-controlled hypertension and type 2 diabetes who developed acute dysarthria, gait instability, and a generalized seizure after a 7-day course of metronidazole totaling 10.5 g. Laboratory evaluation was unremarkable.Stool cultures and pathogen-specific PCR were negative. The MRI shows bilateral symmetric T2/FLAIR hyperintensities in the dentate nuclei, brainstem, and splenium, consistent with MIE. No alternative etiology was identified. This case occurred in an adult without hepatic dysfunction. Metronidazole was discontinued immediately, leading to rapid clinical improvement and complete neurological recovery.

This case highlights that MIE can occur even after short treatment durations and low cumulative doses, particularly in patients without traditional risk factors. Early recognition of the clinical and radiologic features is essential, as prompt drug cessation leads to full reversibility in most cases.