Haloperidol-induced rhabdomyolysis without neuroleptic malignant syndrome in a handicapped child

A 6-year-old severely handicapped boy with haloperidol-induced mild rhabdomyolysis without neuroleptic malignant syndrome is reported. He had suffered from frontal lobe epilepsy, severe mental retardation and involuntary movements. To reduce the involuntary movements, oral administration of haloperidol was started. Haloperidol was effective for the involuntary movements, and he became well. However, his urine was sometimes dark brown, and the myoglobin level in his urine was increased. After discontinuation of haloperidol, his urine never became dark brown. It was suspected that haloperidol might cause mild rhabdomyolysis without neuroleptic malignant syndrome. Neuroleptic malignant syndrome is a rare but severe adverse effect of neuroleptics, and is usually accompanied by rhabdomyolysis. Although there have been a few adult cases presenting rhabdomyolysis without neuroleptic malignant syndrome, this patient might be the first child case with such symptoms. We have to pay attention to this syndrome when using haloperidol even in children.