Teaching NeuroImages: The dentate sign in subacute cerebellar ataxia
Metronidazole neurotoxicity
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A 79-year-old woman developed infectious periaortitis after an abdominal aortic aneurysm repair. A month later, she exhibited vertigo, dysarthria, and unsteady gait, progressing to inability to stand, painful paresthesia, and disorientation. Her examination showed dysmetria, dysdiadochokinesia, and severe cerebellar ataxia. She underwent extensive laboratory investigations, including autoimmune and paraneoplastic panels. Prominent dentate hyperintensity on T2-weighted and fluid-attenuated inversion recovery sequences had been overlooked (figure). The cerebellar syndrome, and the abnormal dentate signal, resolved within 15 days from discontinuing metronidazole. Besides encephalopathy and polyneuropathy, metronidazole can induce subacute cerebellar ataxia by selectively affecting the dentate nucleus.1,2 Recognizing this imaging hallmark identifies a reversible iatrogenic complication and prevents unnecessary testing.
Fluid-attenuated inversion recovery sequences 1 month after initiation of metronidazole (A) showed bilateral symmetrical hyperintensities in the dentate nucleus. Within 15 days after metronidazole discontinuation (B), the signal in the dentate had normalized.
Study funding
No targeted funding reported.
Disclosure
M.T. Jiménez and P.S. Gándara report no disclosures relevant to the manuscript. A.J. Espay has received grant support from the NIH, Great Lakes Neurotechnologies, and the Michael J. Fox Foundation; personal compensation as a consultant/scientific advisory board member for AbbVie, Adamas, Acadia, Acorda, Neuroderm, Impax, Sunovion, Lundbeck, Osmotica Pharmaceutical, and USWorldMeds; publishing royalties from Lippincott Williams & Wilkins, Cambridge University Press, and Springer; and honoraria from USWorldMeds, Lundbeck, Acadia, Sunovion, the American Academy of Neurology, and the Movement Disorders Society. Go to Neurology.org/N for full disclosures.
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Footnotes
Go to Neurology.org/N for full disclosures.
Teaching slides links.lww.com/WNL/B46
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