Exceptionally high creatine kinase levels in risperidone-induced neuroleptic malignant syndrome: A case report.

Neuroleptic malignant syndrome is a rare, fatal antipsychotic-induced idiosyncratic reaction characterised by hyperthermia, altered consciousness, autonomic instability and rigidity with elevated creatine kinase levels and leukocytosis. Neuroleptic malignant syndrome and antipsychotics are significant causes for elevated creatine kinase among the extensive list of differential diagnoses. Risperidone is an atypical antipsychotic drug with anti-serotonergic and anti-dopaminergic properties which has a wide range of side effects, including neuroleptic malignant syndrome. Though the rise in creatine kinase in neuroleptic malignant syndrome is commonly around 2000 to 15,000 IU/L due to myonecrosis, ischaemia and heat production, normal creatine kinase levels in neuroleptic malignant syndrome were also reported. Up to now, only two cases have been reported with creatine kinase levels of more than 50,000 IU/L in neuroleptic malignant syndrome, but neither of them was risperidone-induced. We report the first case of an exceptional rise in creatine kinase levels more than 250-fold in a 16-year-old girl following low-dose risperidone-induced neuroleptic malignant syndrome.