Abnormal nocturnal behavior mimicking REM sleep behavior disorder episodes in a patient with periodic limb movement disorder

Periodic limb movement disorder (PLMD) is a condition in which patients experience frequent periodic limb movements of sleep (PLMS). Synchronized arousal responses cause sleep fragmentation, resulting in insomnia, daytime sleepiness, and fatigue. A 59-year-old man was identified as having intense sleep-talking and body movements, suggesting rapid eye movement (REM) sleep behavior disorder (RBD). Attended video-polysomnography (PSG) revealed that sleep-talking and body movements occurred only during non-REM sleep and were associated with PLMS-induced arousals (periodic leg movement arousal index, 53.2/h). Pramipexole administration improved events during sleep and daytime sleepiness, and the PSG findings and clinical course led to a diagnosis of PLMD. This case demonstrates that PLMD mimics the symptoms of RBD and that a detailed analysis of monitored video PSG is crucial to confirm the diagnosis of RBD and to identify or exclude other causes of sleep talking and behavior.