title: Spontaneous Low-Frequency Cerebral Hemodynamics Oscillations in Restless Legs Syndrome with Periodic Limb Movements During Sleep: A Near-Infrared Spectroscopy Study.
abstract: OBJECTIVE
  Periodic limb movements (PLM) during sleep (PLMS) are associated with cortical and cardiovascular activation. Changes in cerebral hemodynamics caused by cortical activity can be measured using near-infrared spectroscopy (NIRS). We investigated oscillatory components of cerebral hemodynamics during PLM and different sleep stages in restless legs syndrome (RLS) patients with PLMS.
  
  
  METHODS
  Four female RLS patients with PLMS, and four age- and sex-matched normal controls were included. PLM and sleep stages were scored using polysomnography, while the spontaneous cerebral hemodynamics was measured by NIRS. The phase and amplitude of the cerebral oxyhemoglobin concentration [HbO] and the deoxyhemoglobin concentration [Hb] low-frequency oscillations (LFOs) were evaluated during each sleep stage [waking, light sleep (LS; stages N1 and N2), slow-wave sleep (stage N3), and rapid eye movement (REM) sleep]. In RLS patients with PLMS, the cerebral hemodynamics during LS was divided into LS with and without PLM.
  
  
  RESULTS
  The cerebral hemodynamics activity varied among the different sleep stages. There were changes in phase differences between [HbO] and [Hb] LFOs during the different sleep stages in the normal controls but not in the RLS patients with PLMS. The [HbO] and [Hb] LFO amplitudes were higher in the patient group than in controls during both LS with PLM and REM sleep.
  
  
  CONCLUSIONS
  The present study has demonstrated the presence of cerebral hemodynamics disturbances in RLS patients with PLMS, which may contribute to an increased risk of cerebrovascular events.
authors.affiliation: Department of Neurology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Jung Ick
authors.initials: JI
authors.lastname: Byun
authors.affiliation: Department of Neurology, Seoul National University Hospital, Seoul, Korea.|Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea. jungky10@gmail.com.
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Jung
authors.affiliation: Department of Neurology, College of Medicine, Korea University, Seoul, Korea.
authors.forename: Gwan Taek
authors.initials: GT
authors.lastname: Lee
authors.affiliation: Department of Biomedical Engineering, Korea University, Seoul, Korea.
authors.forename: Choong Ki
authors.initials: CK
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, Korea University, Seoul, Korea. bmk515@korea.ac.kr.
authors.forename: Beop Min
authors.initials: BM
authors.lastname: Kim
keywords: hemodynamics; low-frequency oscillations; near-infrared spectroscopy; periodic limb movement during sleep; restless legs syndrome