title: Sleep-related respiratory abnormalities and arousal pattern in achondroplasia during early infancy.
abstract: OBJECTIVE
  To assess sleep-disordered breathing (SDB), sleep architecture, and arousal pattern in infants with achondroplasia and to evaluate the relationship between foramen magnum size and the severity of SDB.
  
  
  METHODS
  A retrospective review of polysomnographic recordings and medical records was performed in infants with achondroplasia and in aged-matched control subjects. All studies were re-scored with the emphasis on respiratory events, sleep state, and arousals. In addition, the neuroimaging study of the brain (magnetic resonance imaging) was reviewed to evaluate foramen magnum diameters and to assess their relationship to SDB.
  
  
  RESULTS
  Twenty-four infants met the criteria for entry into analysis, 12 infants with achondroplasia (A) and 12 control infants (C). There was no significant difference in age or sex. Infants with achondroplasia had a significant increase in total respiratory disturbance index (RDI; A, 13.9 +/- 10.8 versus C, 2.0 +/- 0.9; P < .05). However, there was no significant difference in percentages of active sleep, quiet sleep, or sleep efficiency. Analysis of arousals demonstrated that infants with achondroplasia had a significant decrease in both spontaneous arousal index (A, 10.5 +/- 3.5/hr versus C, 18.6 +/- 2.7; P < .0001) and respiratory arousals (A, 10.3% +/- 6.3% versus C, 27.5 +/- 9.5%; P < .0001). Evaluation of foramen magnum dimensions demonstrated smaller foramen magnum size, but there were no significant correlations between anteroposterior or transverse diameters and RDI.
  
  
  CONCLUSIONS
  Infants with achondroplasia have significant SDB during early infancy. SDB in infants with achondroplasia is not associated with alteration in sleep architecture, possibly because of attenuation of the arousal response. We speculate that the concomitant increased apneic events and decreased arousal response will lead to vulnerability in these infants and may underlie the pathophysiologic mechanism of sudden unexpected death in this population.
authors.affiliation: Department of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: Mathew
authors.initials: M
authors.lastname: Ednick
authors.forename: Brad T
authors.initials: BT
authors.lastname: Tinkle
authors.forename: Jungrak
authors.initials: J
authors.lastname: Phromchairak
authors.forename: John
authors.initials: J
authors.lastname: Egelhoff
authors.forename: Raouf
authors.initials: R
authors.lastname: Amin
authors.forename: Narong
authors.initials: N
authors.lastname: Simakajornboon
mesh_terms: D000130:Achondroplasia / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005539:Foramen Magnum / Q000473:pathology; D006801:Humans; D007223:Infant; D008297:Male; D017286:Polysomnography; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D020921:Sleep Arousal Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology