REM sleep behavior disorder and periodic leg movements in sleep in patients with amyotrophic lateral sclerosis

Abstract

In the last few years, it has been increasingly recognized that patients with amyotrophic lateral sclerosis (ALS) frequently suffer of sleep-related complaints, including insomnia, restless legs syndrome, and daytime sleepiness, although, in the past, many of the nocturnal symptoms have been mainly ascribed to chronic respiratory insufficiency and hypoventilation. In addition, excluding few single cases reported, polysomnographic studies did not look for abnormal motor activity during sleep that could be indicative of Rapid Eye Movements (REM) sleep behavior disorder (RBD) and REM sleep without atonia (RSWA), which are highly prevalent in other neurodegenerative disorders with brainstem involvement. Finally, data on the presence of periodic leg movements in sleep (PLMS) in patients with ALS are sparse. We sought to assess sleep characteristics and the occurrence of abnormal muscle activity during sleep, such as RSWA, RBD, and PLMS in patients with ALS. Forty-one patients with ALS and 26 healthy subjects were submitted to clinical interview and overnight video-polysomnography. Twenty-two patients with ALS (53.6%) reported poor sleep quality. Polysomnographic studies showed that patients with ALS had reduced total time of sleep, increased wakefulness after sleep onset, shortened REM and slow wave sleep, and decreased sleep efficiency compared to control subjects. Polysomnographic abnormalities were not different in patients reporting good or poor sleep, and were not correlated to clinical and demographic variables. PLMS index was significantly higher in patients with ALS than in healthy subjects, and 22 patients (53.6%) showed a PLMS index > 15, vs 4 (15.4%) control subjects ( p < 0.001). Finally, two patients with ALS (4.9%) had RBD, and two more patients presented RSWA (4.9%), whereas no control subjects showed abnormalities of REM sleep. Patients with ALS frequently present abnormalities of sleep that can be documented both at the clinical interview and at the polysomnographic evaluation, including insomnia, fragmented sleep, and increased PLMS. Moreover, abnormalities of REM sleep can sometimes be found in these patients. The authors would like to thank Dr. A. Mattaliano, Ospedale Civico ARNAS of Palermo, Dr. V. La Bella, University of Palermo-Italy, and Dr. G. Borghero, University of Cagliari-Italy, for their important contribution.