Possible contribution of XYY syndrome to neuroleptic malignant syndrome in a child receiving quetiapine.

PURPOSE

A case of early neuroleptic malignant syndrome (NMS) in a child with XYY syndrome after three weeks of quetiapine therapy is reported.

SUMMARY

A four-year-old, 23-kg boy with a history of oppositional defiant disorder, mood disorder, and XYY syndrome was brought to the emergency care center (ECC) for evaluation secondary to somnolence, gait disturbances, and altered mental status. Three weeks prior, he was started on a daily oral dose of quetiapine 25 mg; this was adjusted upward to 400 mg daily. He had been experiencing episodes of severe confusion, somnolence, and extreme agitation. He was also ataxic and unbalanced on his feet. Upon evaluation at the ECC, he was found to have an elevated creatine kinase (CK) concentration, as well as elevated CK-MB and CK-MM levels, both of which were indicative of skeletal muscle damage. He was slightly diaphoretic and displayed mild rigidity accompanied by varying degrees of agitation and confusion. The diagnosis of NMS secondary to quetiapine therapy was made. Quetiapine was discontinued, and the patient was admitted for observation. His symptoms steadily resolved over the course of his hospital stay, and his total CK levels, as well as CK isoenzyme levels, fell over the course of observation. Quetiapine was not restarted at discharge, and no new medications were prescribed.

CONCLUSION

A four-year-old boy with XYY syndrome developed signs and symptoms consistent with early NMS after three weeks of quetiapine therapy. High-dose quetiapine, along with possible baseline liver dysfunction secondary to XYY syndrome, may have contributed to the development of NMS in this patient, which resolved after the discontinuation of quetiapine.