title: Atlanto-occipital hypermobility in subjects with Down's syndrome.
abstract: METHODS
  The upper cervical spines of 57 subjects with Down's syndrome were retrospectively examined, with special attention to atlanto-occipital mobility.
  
  
  OBJECTIVE
  To examine the magnitude of atlanto-occipital mobility and its clinical significance in subjects with Down's syndrome.
  
  
  BACKGROUND
  Atlanto-occipital translation of more than 1 mm in adults implies instability. However, the normal value in children with Down's syndrome has not been established, and the value in Down's syndrome has not been evaluated based on a comparison between subjects with Down's syndrome and control subjects.
  
  
  METHODS
  Measurements were made by Wiesel and Rothman's method in 38 subjects with Down's syndrome and 34 control subjects.
  
  
  RESULTS
  Atlanto-occipital translation in the Down's syndrome group ranged from 0-6.4 mm (mean, 2.3 mm), whereas in the control group it ranged from 0-2.1 mm (mean, 0.61 mm). The difference was statistically significant. Of the 38 subjects with Down's syndrome, 37 were asymptomatic.
  
  
  CONCLUSIONS
  The magnitude of atlanto-occipital translation, as expected, apparently was greater in subjects with Down's syndrome than in control subjects. Although the possibility of neurologic complications should be considered whenever unusually high atlanto-occipital mobility is seen, a majority of the subjects with Down's syndrome were asymptomatic.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Ehime University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
authors.forename: N
authors.initials: N
authors.lastname: Sano
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
authors.forename: S
authors.initials: S
authors.lastname: Oki
authors.forename: T
authors.initials: T
authors.lastname: Shibata
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D012189:Retrospective Studies