Metronidazole Induced Encephalopathy: A Case Report Showing Devastating Course on Consecutive MR Imaging

Abstract

Metronidazole-induced encephalopathy is a rare neurologic adverse effect of an antibiotic drug 'metronidazole'. Although it is usually reversible with immediate cessation of the drug, it can also be fatal when used continuously. Here, we present a 72-yearold female who was on metronidazole for a total of 46 consecutive days. Her initial MRI on the 22nd day of medication use revealed a typical involvement of the cerebellar dentate nuclei, corpus callosum splenium, and periaqueductal midbrain, suggesting metronidazole-induced encephalopathy. However, she continued the medication for another 24 days, until she revisited our emergency department with mental status change. Her consecutive MRI showed diffuse cerebral and brainstem involvement, as well as a more prominent involvement of the dentate nuclei and splenium. We present this case to highlight that it is possible for metronidazole-induced toxic encephalopathy to worsen without immediate withdrawal of the offending drug.

What Is Your Diagnosis?

“…Resolution of clinical signs and MRI lesions in most patients between 3 and 16 weeks after drug discontinuation has been reported in humans. 5 In conclusion, metronidazole neurotoxicity is a cause of cerebellar and central vestibular deficits in dogs. Patient history, including previous or current gastrointestinal conditions and metronidazole administration, should alert the clinician to the possibility of metronidazole toxicosis.…”

“…4 Consistent with the MRI features for the dog of the present report, the most characteristic change in people with metronidazole neurotoxicity is symmetric hyperintensity of dentate nucleus on T2-weighted or FLAIR images, though it can also affect other intracranial sites, such as the midbrain, pons, medulla, and splenium of corpus callosum. 5,6 Tauro et al 3 reported non-contrast-enhancing, symmetric T2 and FLAIR hyperintensity of the dentate nuclei in a dog with metronidazole neurotoxicity. It is important to note that in that study, 3 only 1 of the 19 dogs with clinically suspected metronidazole neurotoxicity that had MRI performed showed changes to the dentate nuclei, underscoring the possibility of premature exclusion of a reversible condition based on normal imaging findings alone.…”

“…It is important to note that in that study, 3 only 1 of the 19 dogs with clinically suspected metronidazole neurotoxicity that had MRI performed showed changes to the dentate nuclei, underscoring the possibility of premature exclusion of a reversible condition based on normal imaging findings alone. A geriatric woman who continued metronidazole treatment for 24 days after onset of clinical signs and appearance of MRI lesions showed worsening of signs and imaging features, which progressed from the involvement of dentate nuclei, splenium, and periaqueductal midbrain to that of the cerebral white matter and brainstem, 5 indicating potentially more diffuse lesions in progressive cases. Resolution of clinical signs and MRI lesions in most patients between 3 and 16 weeks after drug discontinuation has been reported in humans.…”