Periodic limb movements during REM sleep in multiple sclerosis: a previously undescribed entity

Abstract

Christian Veauthier,1 Gunnar Gaede,2,3 Helena Radbruch,2 Joern-Peter Sieb,4,5 Klaus-Dieter Wernecke,6,7 Friedemann Paul2,8 1Interdisciplinary Center of Sleep Medicine, Charité University Medicine Berlin, Germany; 2NeuroCure Clinical Research Center, Charité University Medicine Berlin, Germany; 3Department of Neurology, St Joseph Hospital Berlin-Weissensee, Berlin, Germany; 4Department of Neurology, HELIOS Hanseklinikum Stralsund, Stralsund, Germany; 5Department of Neurology, University Hospital Bonn, Bonn, Germany; 6CRO SOSTANA GmbH, Berlin, Germany; 7Institute of Medical Biometry, Charité University Medicine Berlin, Berlin, Germany; 8Clinical and Experimental Multiple Sclerosis Research Center, Department of Neurology, Charité University Medicine Berlin, Berlin, Germany Background: There are few studies describing periodic limb movement syndrome (PLMS) in rapid eye movement (REM) sleep in patients with narcolepsy, restless legs syndrome, REM sleep behavior disorder, and spinal cord injury, and to a lesser extent, in insomnia patients and healthy controls, but no published cases in multiple sclerosis (MS). The aim of this study was to investigate PLMS in REM sleep in MS and to analyze whether it is associated with age, sex, disability, and laboratory findings. Methods: From a study of MS patients originally published in 2011, we retrospectively analyzed periodic limb movements (PLMs) during REM sleep by classifying patients into two subgroups: PLM during REM sleep greater than or equal to ten per hour of REM sleep (n=7) vs less than ten per hour of REM sleep (n=59). A univariate analysis between PLM and disability, age, sex, laboratory findings, and polysomnographic data was performed. Results: MS patients with more than ten PLMs per hour of REM sleep showed a significantly higher disability measured by the Kurtzke expanded disability status scale (EDSS) (P=0.023). The presence of more than ten PLMs per hour of REM sleep was associated with a greater likelihood of disability (odds ratio 22.1; 95% confidence interval 3.5–139.7; P<0.0001), whereas there were no differences in laboratory and other polysomnographic findings. Conclusion: PLMs during REM sleep were not described in MS earlier, and they are associated with disability measured by the EDSS. Keywords: restless legs syndrome, spinal cord, sleep disorders, disability, clinical neurophysiology, polysomnography