A 15-year-old girl presented with ataxia and dysmetria 7 days after beginning treatment with metronidazole for Crohn disease. MRI revealed bilateral symmetric T2/FLAIR hyperintense lesions of the dentate nuclei (Fig. 1). The lesions did not show contrast enhancement or restricted diffusion. No other lesions were seen. The lesions resolved completely after metronidazole was discontinued (Fig. 2).

Fig. 1
figure 1

Axial FLAIR image

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Fig. 2
figure 2

Axial FLAIR image shows complete resolution

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Metronidazole is an antibiotic used in the treatment of Crohn disease and anaerobic-related infections [1]. Metronidazole-induced cerebellar toxicity is a rare complication. Patients often present with cerebellar symptoms, including ataxia or dysarthria, which often gradually resolve after ceasing treatment [2]. The most characteristic radiological finding is bilateral symmetric hyperintense lesions of the dentate nuclei [1], and less commonly the brainstem, corpus callosum, and subcortical white matter.

Neurotoxicity should be suspected in patients presenting with cerebellar symptoms in the presence of treatment with metronidazole.