1001 A Case of Unusual Nocturnal Movements Consistent with Paroxysmal Hypnogenic Dyskinesia

Abstract

Abstract Introduction Paroxysmal hypnogenic dyskinesia (PHD) is a rare subset of paroxysmal dyskinesias characterized by recurring involuntary dystonic or choreoathetoid movements that occur during sleep or immediately after an arousal from sleep. These episodes often occur without loss of consciousness or trigger and lack association with epileptiform electroencephalography (EEG) activity. Report of case(s) A 61-year-old male with obstructive sleep apnea compliant with PAP was referred for abnormal nighttime movements for the past 9 years. The episodes were characterized by stereotyped involuntary dystonic posturing involving his upper extremities or his entire body lasting up to 15 seconds. The onset of the events occurred invariable during nighttime sleep and resulted in awakenings from sleep. He denied dream enactment as well as other symptoms suggestive of sleep-related movement disorders or parasomnias. Sleep deprived EEG demonstrated left temporal slowing during wakefulness and drowsiness and captured a typical event that occurred during NREM stage II sleep and had no ictal correlate. An MRI of the brain was unremarkable. During overnight polysomnogram, his current PAP settings were found to be effective, and three episodes of body stiffening consistent with his typical events were captured. These episodes were found to occur after awakening from REM sleep and lasted less than 10 seconds each. There was no EEG correlate, and REM atonia was preserved throughout. The patient was started on oxcarbazepine for the nocturnal movements, which reduced the frequency of events from 12 to 4 events per night. Oxcarbazepine was tapered and discontinued due to side effects and incomplete control of the events. Genetic testing for epilepsy syndromes is pending. Conclusion PHD is a rare syndrome of involuntary movements which begin during sleep or cause awakenings from sleep and can be misdiagnosed as a sleep disorder. It is crucial for the sleep physician to be aware of possible neurological causes of sleep-related movement disorders. Furthermore, our patient’s partial response to oxcarbazepine may further support that PHD may have an epileptic origin although not well characterized. Support (if any) Advancing Innovation in Residency Education (AIRE) Pilot Program Training Grant