title: Periodic limb movements during REM sleep in multiple sclerosis: a previously undescribed entity.
abstract: 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.
  
  
  CONCLUSIONS
  PLMs during REM sleep were not described in MS earlier, and they are associated with disability measured by the EDSS.
authors.affiliation: Interdisciplinary Center of Sleep Medicine, Charité University Medicine Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Veauthier
authors.affiliation: NeuroCure Clinical Research Center, Charité University Medicine Berlin, Germany ; Department of Neurology, St Joseph Hospital Berlin-Weissensee, Berlin, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Gaede
authors.affiliation: NeuroCure Clinical Research Center, Charité University Medicine Berlin, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Radbruch
authors.affiliation: Department of Neurology, HELIOS Hanseklinikum Stralsund, Stralsund, Germany ; Department of Neurology, University Hospital Bonn, Bonn, Germany.
authors.forename: Joern-Peter
authors.initials: JP
authors.lastname: Sieb
authors.affiliation: CRO SOSTANA GmbH, Berlin, Germany ; Institute of Medical Biometry, Charité University Medicine Berlin, Berlin, Germany.
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Wernecke
authors.affiliation: NeuroCure Clinical Research Center, Charité University Medicine Berlin, Germany ; Clinical and Experimental Multiple Sclerosis Research Center, Department of Neurology, Charité University Medicine Berlin, Berlin, Germany.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Paul
keywords: clinical neurophysiology; disability; polysomnography; restless legs syndrome; sleep disorders; spinal cord