[Dyskinesia-hyperpyrexia syndrome triggered by overdose of istradefylline: a case report].

We present a 71-year-old woman with an eight-year history of Parkinson's disease (PD). She began to experience wearing-off at the age of 66 and subsequently developed dyskinesia. She had worsened dyskinesias for three days, followed by a high fever, and she was subsequently hospitalized. On admission, severe dyskinesia, hyperpyrexia, and elevation of serum creatine kinase were observed. Severe dyskinesia without rigidity continued throughout the day and she was diagnosed with dyskinesia-hyperpyrexia syndrome (DHS). She was treated with standard medical care and anti-parkinsonian medications were reduced drastically. Dyskinesia started to wane three days after admission and almost disappeared on day twelve. Prior to admission, the patient reported she had been taking two to three times the dose prescribed of istradefylline, which was the suspected to be a trigger of DHS. Because DHS is a rare but potentially life-threatening complication, early recognition and diagnosis is vital. A proper treatment strategy for DHS may include standard medical care together with reduced anti-parkinsonian medications.