title: Respiratory-related leg movements and their relationship with periodic leg movements during sleep.
abstract: OBJECTIVE
  To describe the time structure of leg movements (LM) in obstructive sleep apnea (OSA) syndrome, in order to advance understanding of their clinical significance.
  
  
  METHODS
  Sleep Research Centre, Oasi Institute (IRCCS), Troina, Italy.
  
  
  METHODS
  Sleep laboratory.
  
  
  METHODS
  Eighty-four patients (16 females, 68 males, mean age 55.1 y, range 29-74 y).
  
  
  METHODS
  Respiratory-related leg movements (RRLM) and those unrelated to respiratory events (NRLM) were examined within diagnostic polysomnograms alone and together for their distributions within the sleep period and for their periodicity.
  
  
  RESULTS
  Patients with OSA and RRLM exhibited more periodic leg movements in sleep (PLMS), particularly in NREM sleep. A gradual decrease in number of NRLM across the sleep period was observed in patients with RRLM. This pattern was less clear for RRLM. Frequency histograms of intermovement intervals of all LMs in patients with RRLM showed a prominent first peak at 4 sec, and a second peak at approximately 24 sec coincident with that of PLMS occurring in the absence of OSA. A third peak of lowest amplitude was the broadest with a maximum at approximately 42 sec. In patients lacking RRLM, NRLM were evident with a single peak at 2-4 sec. A stepwise linear regression analysis showed that, after controlling for a diagnosis of restless legs syndrome and apnea-hypopnea index, PLMS remained significantly associated with RRLM.
  
  
  CONCLUSIONS
  The time structure of leg movements occurring in conjunction with respiratory events exhibit features of periodic leg movements in sleep occurring alone, only with a different and longer period. This brings into question the validity, both biologic and clinical, of scoring conventions with their a priori exclusion from consideration as periodic leg movements in sleep.
authors.affiliation: Sleep and Epilepsy Center, Neurocenter of 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 Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland ; Laboratory of Autonomic Nervous System Disorders, Sechenov First Moscow State Medical University, Moscow, Russia.
authors.forename: Irina
authors.initials: I
authors.lastname: Zavalko
authors.affiliation: Universitätsklinik für Neurologie, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Bassetti
authors.affiliation: Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Colamartino
authors.affiliation: Department of Internal Medicine, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Pons
authors.affiliation: Sleep Research Centre, Department of Neurology I.C., Oasi Institute (IRCCS), Troina, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferri
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007558:Italy; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D010507:Periodicity; D017286:Polysomnography; D012119:Respiration; D012148:Restless Legs Syndrome / Q000175:diagnosis; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*
keywords: Periodicity index; periodic leg movements; respiratory-related leg movements; sleep apnea; time distribution