title: Prevalence of the foramen arcuale of the atlas in a Saudi population.
abstract: OBJECTIVE
  To describe the prevalence and morphologic characteristics of the foramen arcuale of the atlas vertebra in the Saudi population and propose a simplified classification system.
  
  
  METHODS
  A cross-sectional hospital-based study was conducted at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia from September 2010 to February 2011. During the 6-month period, 453 CT studies of the cervical spine were evaluated for the presence of different degrees of this anatomic variant using a clinically relevant classification system.
  
  
  RESULTS
  We found 52.1% (236 patients) to have no degree of osseous bridging, 31.8% (144 patients) had some degree of incomplete posterior osseous bridging, and 16.1% had the complete form of the foramen arcuale. The anomaly showed a male predilection that only reached statistic significance for those on the left side (p=0.016). Patients with a well-developed variant were older than those without the anomaly, but only by 7.46 years (p=0.034). These anomalies showed a propensity for bilaterality, which is a source for concern (kappa=0.592, approximate significance=0.00).
  
  
  CONCLUSIONS
  Compared to data from other countries, this anomaly has a higher prevalence in our population, indicating that further investigations are needed.
authors.affiliation: Division of Neurosurgery, Faculty of Medicine, King Abdulaziz University, Kingdom of Saudi Arabia. sbaeesa@kau.edu.sa
authors.forename: Saleh S
authors.initials: SS
authors.lastname: Baeesa
authors.forename: Rakan F
authors.initials: RF
authors.lastname: Bokhari
authors.forename: Khalid M
authors.initials: KM
authors.lastname: Bajunaid
authors.forename: Mohammad J
authors.initials: MJ
authors.lastname: Al-Sayyad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001270:Cervical Atlas / Q000000981:diagnostic imaging / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D005539:Foramen Magnum / Q000000981:diagnostic imaging / Q000473:pathology*; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D012529:Saudi Arabia / Q000453:epidemiology; D014057:Tomography, X-Ray Computed; D055815:Young Adult