title: An evidence-based recommendation for a new definition of respiratory-related leg movements.
abstract: OBJECTIVE
  Current sleep scoring rules exclude leg movements that occur near respiratory events from being scored as periodic leg movements during sleep (PLMS) but differ in whether they exclude leg movements occurring at the end (WASM/ IRLSSG) or during a respiratory event (AASM). The aim of the present study was to describe the distribution of leg movements in relation to respiratory events and to contribute to an evidence-based rule for the identification and scoring of respiratory-related leg movements (RRLMs).
  
  
  METHODS
  Retrospective chart review and analysis of polysomnographic recordings.
  
  
  METHODS
  Clinical sleep laboratory.
  
  
  METHODS
  64 patients with polysomnographic recordings between January 2010 and July 2011, aged 18 to 75 years, with AHI >20, ODI >10, more than 50% of apneas being obstructive, >15 leg movements of any type per hour of sleep, no more than 20% of total sleep time with artifacts and no medical condition or medication that could influence leg movements or respiratory disturbances.
  
  
  METHODS
  None.
  
  
  RESULTS
  Back-averaging of leg movement activity (LMA) with respect to respiratory events revealed that LMA was present shortly before the end of the respiratory events, but occurred mostly following respiratory events with peak onset of LMA 2.5 s after respiratory event termination. Increased LMA before the beginning of the respiratory event consisted mainly of the tail of LMA after the end of the previous respiratory event. Change-point analysis indicated that LMA was increased over an interval of -2.0 s to +10.25 s around the end of respiratory events. Changing the definition of RRLMs had a significant influence on PLMS counts. The number of patients with obstructive sleep apnea (OSA) with PLMS index >15 was 80% when considering the WASM/ IRLSSG definition, 67% for the AASM criteria, and 41% when based on the interval identified by change-point analysis (-2.0 to 10.25 s).
  
  
  CONCLUSIONS
  Leg movements are not augmented at the beginning or middle of respiratory events but are increased around the end of respiratory events over a period significantly longer than specified in the AASM and the WASM/ IRLSSG rules. Both rules underestimate the number of RRLMs and thus overestimate the number of PLMS in patients with OSA.
authors.affiliation: Sleep and Epilepsy Center, Neurocenter of the Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.
authors.forename: Mauro
authors.initials: M
authors.lastname: Manconi
authors.affiliation: Sleep and Epilepsy Center, Neurocenter of the Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.|Institute for Bio-Medical Problems, Russian Academy of Science, Moscow, Russia.
authors.forename: Irina
authors.initials: I
authors.lastname: Zavalko
authors.affiliation: Sleep Center, Scientific Institute of Pavia, Salvatore Maugeri Foundation IRCCS, Pavia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fanfulla
authors.affiliation: Department of Psychiatry, Sleep Disorders Clinical Research Program, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: John W
authors.initials: JW
authors.lastname: Winkelman
authors.affiliation: Sleep and Epilepsy Center, Neurocenter of the Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.
authors.forename: Stephany
authors.initials: S
authors.lastname: Fulda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D017286:Polysomnography; D012119:Respiration; D012189:Retrospective Studies; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D055815:Young Adult
keywords: Respiratory-related leg movements; periodic leg movements; sleep apnea