Posterior reversible encephalopathy syndrome in Parkinson disease probably caused by prominent supine hypertension and blood pressure fluctuation.

We present the case of a 77-year-old man with a 10-year history of Parkinson disease (PD), who developed posterior reversible encephalopathy syndrome (PRES). We diagnosed the case as PRES based on clinical features and MRI findings. He experienced orthostatic hypotension and supine hypertension, including nocturnal hypertension. PRES may result from marked supine/nocturnal hypertension and fluctuation in blood pressure. In addition, exacerbated factors could be representative of neuroleptic malignant syndrome. The hypertensive effect of istradefylline should also not be excluded. We believe this is the first case report of a patient with PD developing PRES without vasopressor use.