Metronidazole-induced encephalopathy and polyneuropathy

Though effective, metronidazole poses multiple side effects, especially with prolonged therapy or high dosage. Among these are metronidazole-induced peripheral neuropathy and encephalopathy, which are severely debilitating. We describe a middle-aged man with a liver abscess who was treated with metronidazole 2.4 g/day for nearly 2 months, and who went on to develop dysarthria, ataxic gait and sensory loss, including numbness and burning paraesthesia in his limbs. Neurological assessment comprised nerve conduction studies (NCS) and magnetic resonance imaging (MRI). NCS indicated axonal neuropathy, and MRI revealed T2/FLAIR hyperintensities in the dentate nuclei and corpus callosum, which are indicative of toxic encephalopathy. Symptoms improved considerably after metronidazole was stopped. This case documents the possibility of metronidazole-induced severe neurological sequelae, such as peripheral neuropathy and encephalopathy, especially with high doses (140 gm) or prolonged therapy. Clinicians must remain vigilant for evidence of neurotoxicity in metronidazole-treated patients, especially those on prolonged or high-dose therapy.