Reporting on Adverse Clinical Events

A 43-year-old female patient developed sudden bilateral hearing loss, ataxia, and vertigo approximately 20 days after starting metronidazole (total dose = 28 g) as part of a regimen for the treatment of Helicobacter pylori. A physical examination revealed lethargy, encephalopathy, slurred speech, and apathy. Despite normal muscle tone, the muscle force was decreased on the right side of the body. Screenings for infectious etiologies were negative. A brain magnetic resonance imaging demonstrated bilateral symmetric T2-weighted hypersignal lesions in dentate nucleus, the splenium of corpus callosum, and cerebral white matter. Metronidazole was discontinued and treatment with L-carnitine and coenzyme Q10 was initiated with significant improvements observed in hearing and walking within 3 days. The authors concluded that this patient experienced metronidazoleinduced encephalopathy and neurotoxicity based on the temporal relationship between the administration of the drug and the appearance and resolution of symptoms. Suggested mechanism of action included mitochondrial dysfunction, inhibition of protein synthesis by binding to neural RNA, and modifying cerebellar and vestibular g-aminobutyric acid receptors. Metronidazole [“Flagyl”] Agah E et al (A Tafakhori, NeuroImmunology Research Association, Universal Scientific Education and Research Network, Tehran, Iran; e-mail: a_tafakhori@sina.tums.ac.ir) Metronidazole-induced neurotoxicity presenting with sudden bilateral hearing loss, encephalopathy, and cerebellar dysfunction. Eur J Clin Pharmacol 73:249–250 (Feb) 2017