Metronidazole-induced encephalopathy: a systematic review.

BACKGROUND AND AIMS: Metronidazole, a commonly used antibiotic drug, can cause adverse effects in the central nervous system termed metronidazole-induced encephalopathy, leading to diagnostic challenges. The condition is rare and a detailed description of its phenotype is lacking. In this systematic review we investigated the clinical features of metronidazole-induced encephalopathy to promote recognition and elaborate the description. METHODS: We performed a systematic literature search using PubMed.gov and hand searched the reference lists of included articles and other publications of interest. We included case series and single reports describing individual patients developing symptoms from the central nervous system in relation to metronidazole treatment. Data were extracted and analyzed descriptively. RESULTS: We identified 779 publications of which 112 papers comprising 136 patients were included. Typical findings were dysarthria, gait instability, limb dyscoordination and altered mental status. Frequently, patients concomitantly presented with metronidazole-induced polyneuropathy. Liver disease was the most common pre-existing condition. MRI showed a characteristic pattern of reversible symmetrical hyperintense lesions on T2/FLAIR of the dentate nuclei in 90% of patients. Most patients improved significantly after discontinuation of metronidazole. Poor outcome was associated with severe comorbidity. CONCLUSION: Metronidazole-induced encephalopathy should be considered in patients presenting with neurological symptoms in relation to newly initiated or prolonged metronidazole treatment. MRI changes are highly characteristic and specific. Patients with liver disease are at increased risk. Prognosis is good if recognized early.

Convulsive Seizures as Presenting Symptom of Metronidazole-Induced Encephalopathy: A Case Report.

INTRODUCTION: Encephalopathy and convulsive seizures are rare manifestations of metronidazole toxicity. The incidence is unknown, but the condition has most frequently been reported in patients in their fifth to sixth decades. Usually, this condition is regarded as reversible, but permanent deficits and even death have been reported. CASE REPORT: A 66-year-old female patient undergoing metronidazole treatment for pleural empyema was admitted to our institution after her second episode of seizure. Over the course of 1 week after admittance, the patient developed several convulsive seizures along with progressive cerebellar dysfunction and cognitive impairment. MRI revealed bilateral, symmetrical hyperintense signal changes in the pons and dentate nuclei. EEG, ECG, lumbar puncture, and blood samples were normal. The patient improved already 2-3 days after discontinuation of metronidazole and was discharged fully recovered after 17 days. Follow-up clinical assessment and MRI were unremarkable. CONCLUSION: Metronidazole-induced encephalopathy is a rare condition, and due to a general lack of awareness the diagnosis is often delayed. This condition should be considered in metronidazole-treated patients presenting with unprovoked seizures, myoclonus, cerebellar signs, and encephalopathy. Characteristic MRI lesions may support the clinical suspicion.