Chapter 133 – Movement Disorders in Sleep and Restless Legs Syndrome (Ekbom's Syndrome)

Thomas Willis, in 1685, was the first to describe patients troubled by restless leg movements, and he noted that they often had insomnia. Ekbom published a series of articles about restless legs syndrome (RLS) in the 1940s. Symonds described abnormal twitches during sleep—"nocturnal myoclonus"—which he distinguished from "common nocturnal jerks." The latter are now called sleep onset myoclonus, hypnic jerks, or sleep starts and are considered normal, as are the twitches of various skeletal muscles without synchrony, periodicity, or symmetry usually seen during rapid eye movement (REM) sleep. Symonds's patients with nocturnal myoclonus all had insomnia, and at least one patient had periodic arousals at 1-minute intervals, consistent with the modern definition of periodic limb movements disorder of sleep (PLMD; this term has replaced nocturnal myoclonus ). The current definition allows for the fact that patients present with hypersomnia, although cause-effect ties are unproven.