Sleep-Related Myoclonus in Rheumatic Pain Modulation Disorder (Fibrositis Syndrome) and in Excessive Daytime Somnolence

A new syndrome, Rheumatic Pain Modulation Disorder (RPMD) with sleep‐related myoclonus (involuntary periodic leg movements), with no differences in evening and morning sleepiness, number of limb movements, movement arousals, awakenings after sleep onset, sleep duration, and percent sleep stages is described.

Abstract

We describe a new syndrome, Rheumatic Pain Modulation Disorder (RPMD) ("fibrositis syndrome") with sleep-related myoclonus (involuntary periodic leg movements). Measures of sleepiness, fatigue and pain, before and after sleep, and aspects of sleep of nine subjects (Ss) with RPMD and sleep-related myoclonus were compared to nine subjects with excessive daytime somnolence and sleep-related myoclonus. In eight of the RPMD with sleep-related myoclonus and three of those with daytime sleepiness, an alpha (7.5-11 Hz) EEG Non-Rapid Eye Movement sleep disorder was demonstrated. The RPMD with sleep-related myoclonus group contained a greater number of women, more pain, morning fatigue, and disturbances in sleep (more stage changes and alpha EEG sleep prior to leg myoclonus); but in comparison to the sleep-related myoclonus, daytime somnolent group, there were no differences in evening and morning sleepiness, number of limb movements, movement arousals, awakenings after sleep onset, sleep duration, and percent sleep stages.