title: Body position and obstructive sleep apnea in children with Down syndrome.
abstract: BACKGROUND
  Children with Down syndrome (DS) commonly have obstructive sleep apnea syndrome (OSAS) and may assume a unique sleeping position not systematically described previously. We describe this sleep position in DS and explore its relationship with OSAS in comparison to control children (CC).
  
  
  METHODS
  Overnight video-polysomnograms (PSG) of consecutive children with DS (age 2-18 y), referred to our center between April 2008 and October 2009, were retrospectively analyzed by a single scorer (ES). CC group comprised age and gender matched, non-syndromic, neurologically intact children referred to us for suspected OSAS over the same period.
  
  
  RESULTS
  Each group had 17 subjects matched for age (median [IQR]; 6 [4-8]) and gender (65% female). DS group had higher BMI (median [IQR]; 18.8 [17.4-21.0]) than CC (17 [14.7 -18.8]; p = 0.03). There were however no significant differences (median [IQR]) between DS and CC with respect to sleep time in minutes (460 [425-499] vs 424[410-483]), sleep efficiency (%) (90.9 [87.4-92.4] vs 88.6 [79.9-93.1]), REM time (%) (17.1 [14.2-22.1] vs 19.2 [14.9-22.1]), supine time (%) (40.7 [24.8-56.0] vs 15.8 [0.40-44.5], p 0.06), mean oxygen saturation (%) (95 [94-96] vs 96 [95-97]), oxygen saturation nadir (89 [86-91] vs 89[94-92]), or total apnea-hypopnea index (4.3 [3-7.8] vs 5.1[1.9-9.6]). Despite these similarities between the groups, 9 (53%) DS children slept seated bent forward with head resting on bed for at least part of the total sleep time (%) (7.8 ± 10.9, range 0.8-35.7).This was absent in the CC group (p = 0.06).
  
  
  CONCLUSIONS
  Some DS children assume a peculiar body position, sitting cross-legged flopped-forward with head resting on bed while asleep. This is absent in age- and gender-matched controls showing otherwise similar PSG characteristics. The reason for this posture is unclear from this study. However, this novel report of a unique sleeping position would provide us with a basis to conduct a prospective study involving a larger population to ascertain the contribution of this position for OSAS protection or to determine if it may be forme fruste parasomnia.
authors.affiliation: Neurological Institute, Sleep Disorder Center, Cleveland Clinic Foundation, Cleveland, OH, USA. senthilvelegambaram@yahoo.com
authors.forename: Egambaram
authors.initials: E
authors.lastname: Senthilvel
authors.forename: Jyoti
authors.initials: J
authors.lastname: Krishna
mesh_terms: D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D011187:Posture / Q000502:physiology; D016684:Prone Position / Q000502:physiology; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000209:etiology*; D016683:Supine Position / Q000502:physiology; D014741:Video Recording