Cerebellar ataxia after a single day of metronidazole use: Case report

Cerebellar ataxic syndromes, although uncommon, have been reported previously in patients taking metronidazole. However, almost all cases describe instances where patients were taking prolonged or high doses of the drug. We report a 65-year-old man who consumed 400 mg of metronidazole 3 times over 1 day and presented with slurring of speech, imbalance while walking and diplopia. The symptoms developed the day after consumption of metronidazole. Examination showed slurring of speech, gaze-evoked nystagmus, and dysmetria in all limbs. MRI brain revealed symmetric hyperintense lesions in the dentate nucleus and pons on T2-weighted imaging and FLAIR, which have a well-established association with metronidazole-induced central nervous system (CNS) toxicity. On discontinuation of the drug, symptoms improved, and complete recovery was noted at follow-up 2 weeks later. This case indicates that CNS side effects of metronidazole may not necessarily occur only at high doses or after prolonged courses of metronidazole, but may occur as an idiosyncratic reaction to the drug. Reasons for variable susceptibility require further investigation.