title: Periodic limb movements in children: prevalence in a referred population.
abstract: OBJECTIVE
  To determine the prevalence of periodic limb movements of sleep (PLMS) in children referred for evaluation of sleep disorders.
  
  
  METHODS
  A retrospective analysis of all overnight polysomnograms (PSG) performed at a tertiary-level pediatric care facility.
  
  
  METHODS
  All PSG studies were performed in the pediatric sleep laboratory associated with the Alberta Children's Hospital in Calgary, AB, Canada. The pediatric sleep laboratory was situated in the Foothills Hospital Alberta Lung Association Sleep Center until August 2002. At that time, the pediatric sleep laboratory was relocated to the Alberta Children's Hospital.
  
  
  METHODS
  All children of any age undergoing PSG for any reason between October 1999 and March 2003.
  
  
  RESULTS
  All PSG records were reviewed, and the following data was extracted: periodic limb movement index (PLM index), periodic limb movements with arousal index (PLM w/arousal index), apnea-hypopnea index (AHI), and patient demographics (age, sex, comorbidities). A total of 591 PSG studies were reviewed. Thirty-three of the 591 children (5.6%) had evidence of PLMs > 5 per hour. Twenty of the 33 (60.0%) had coexistent obstructive sleep apnea (AHI > 1/hour). Only 7 of the 591 children studied (1.2%) had evidence of PLM > 5 per hour with no other comorbidity. Two of 13 children with PLM > 5 per hour and no evidence of obstructive sleep apnea had attention-deficit/hyperactivity disorder. The prevalence of PLMS in the 28 of the 591 subjects with a preexisting diagnosis of ADHD was increased at 7.1%.
  
  
  CONCLUSIONS
  PLMS is an uncommon disorder of childhood. In a select population at increased risk for having a sleep disorder, the prevalence of isolated PLMS is only 1.2%.
authors.affiliation: Division of Respiratory Medicine, Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada. val.kirk@calgaryhealthregion.ca
authors.forename: Valerie G
authors.initials: VG
authors.lastname: Kirk
authors.forename: Shelly
authors.initials: S
authors.lastname: Bohn
mesh_terms: D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D020189:Nocturnal Myoclonus Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D017286:Polysomnography; D015995:Prevalence; D012017:Referral and Consultation; D012189:Retrospective Studies