Dystonic reaction associated with ondansetron administration in a patient with normal pressure hydrocephalus.

A 77-year-old female with normal pressure hydrocephalus underwent urgent revision of the abdominal component of a ventriculoperitoneal shunt. Upon emergence from an uneventful general anesthetic, the patient exhibited cogwheel rigidity with decerebrate posturing and a markedly irregular respiratory rate. This prohibited extubation and prompted an unplanned intensive care unit admission. Ondansetron was the only medication administered that had previously been associated with dystonic reactions. In a previous procedure, the patient had been given ondansetron without a similar reaction. This presentation may have been provoked by existing pathology such as her underlying normal pressure hydrocephalus and small increases in intracranial pressure.