Neuroleptic malignant syndrome in an adolescent with the GNAO1 mutation movement disorder phenotype: a challenging diagnosis

Mónica Santos, Neurology, Department of Neurosciences and Mental Health, Centro Hospitalar Universitário Lisboa Norte. Lisbon, Portugal
Tiago Proença dos Santos, Neuropediatrics, Department of Pediatrics, Centro Hospitalar Universitário Lisboa Norte. Portugal
Sofia Almeida, Pediatric Intensive Care Unit, Department of Pediatrics, Centro Hospitalar Universitário Lisboa Norte. Portugal
Miguel Coelho, Neurology, Department of Neurosciences and Mental Health, Centro Hospitalar Universitário Lisboa Norte; Instituto
António Levy, Neuropediatrics, Department of Pediatrics, Centro Hospitalar Universitário Lisboa Norte. Portugal

Introduction: Neuroleptic malignant syndrome (NMS) is a rare and life-threatening condition resulting from exposure to dopamine-blocking agents. GNAO1 mutations are a neurodevelopmental disorder associated with a hyperkinetic movement disorder, usually treated with dopamine-blocking agents. Case report: A 16-year-old adolescent, previously diagnosed with a GNAO1 dyskinetic movement disorder, and prescribed tetrabenazine, chlorpromazine and clonidine, was admitted during the summer due to nausea, fever and a slight worsening of dyskinesias. Initially, a heat stroke was assumed. A few days later, the patient manifested generalized dyskinesias, refractory hyperthermia, diaphoresis and progressive worsening of consciousness, suggesting neuroleptic malignant syndrome. Neuroleptic treatment was stopped, and the patient was started on dantrolene and admitted to the pediatric intensive care unit. The patient eventually recovered over the subsequent two months, symptomatic treatment for dyskinesias was slowly introduced, except chlorpromazine, and he was admitted to a rehabilitation center. Discussion: This case illustrates the diagnostic challenge of malignant neuroleptic syndrome in children and adolescents, particularly in patients with previous dyskinetic movement disorders treated with dopamine antagonists.