Atypical extrapyramidal syndrome: metamizole-associated hemidystonia – A case report and review of cardiovascular implications in analgesic safety

Drug-induced extrapyramidal syndrome usually has clinical features like dyskinesia, dystonia, akathisia, Gilles de la Tourette syndrome, myoclonus, and Parkinsonism. The most common drugs that cause drug-induced extrapyramidal syndrome are neuroleptics. Metamizole (dipyrone) is a widely used non-opioid analgesic in human medicine. Metamizole is generally considered a safe medication, though it is not entirely without potential side effects. There have been no reports of people using metamizole experiencing extrapyramidal syndrome symptoms such as hemidistonia. A 42-year-old man presented with hemidystonia and dysphasia after receiving metamizole injection. He had a similar episode in the past associated with the same medication. Neurological examination revealed hemidystonia without loss of consciousness, seizure, or headache. The patient was also being treated for pulmonary tuberculosis and had comorbid anemia, thrombocytopenia, elevated liver enzymes, hypoalbuminemia, hyponatremia, and hypokalemia. A contrast-enhanced head CT scan showed no structural abnormalities. Intravenous administration of diphenhydramine led to symptom resolution. Metamizole was discontinued, and no recurrence occurred during the follow-up period. This case highlights metamizole-associated hemidystonia as a rare but reversible extrapyramidal reaction. Clinicians should consider this potential adverse effect, especially in patients with metabolic or hepatic dysfunction.