Purpose or Case Report: Metronidazole is a commonly used and effective antimicrobial agent for gastrointestinal and genitourinary infections throughout the world. Common side effects of nausea, taste/appetite changes, and headache are well known, however, CNS side effects such as cerebellar dysfunction, dysarthria, and seizures have been reported even at therapeutic levels in rare instances. A previous review of the case literature concluded that resolution of symptoms was independent of age, however, evaluation of the pediatric population is limited.
Methods & Materials: The patient is a 17-year-old autistic male who presented with one day history of ataxia and leaning to the right during ambulation. He was afebrile, and lumbar puncture revealed no evidence of meningitis. There were no recent illnesses or sick contacts. Past medical history was significant for Hirschsprung's Disease.
Results: There is diffuse T2 signal abnormality throughout the cerebellar hemispheres with notable involvement of the cerebellar cortex and dentate nuclei. Symmetrical regions of abnormal FLAIR/T2 signal hyperintensity are also present within the dorsal pons and medulla. There is ill-defined T2 signal hyperintensity within the callosal splenium which demonstrates corresponding restricted diffusion. There is no associated contrast enhancement. Review of the patient's medical record showed long-term use of metronidazole. MRI changes and mental status improved following withdrawal of the medication.
Conclusions: Unexplained change in mental status often prompts imaging evaluation. The MR imaging findings of metronidazole induced CNS toxicity in this case expands on the limited literature of this condition in the pediatric population. Additionally, the unique imaging findings discussed will serve to initiate prompt cessation of therapy in an otherwise reversible disease course.