title: Quantitative Measurements of the Skull Base and Craniovertebral Junction in Congenital Occipitalization of the Atlas: A Computed Tomography-Based Anatomic Study.
abstract: OBJECTIVE
  To study the craniovertebral junction and determine the anatomic characteristics of occipitalization of the atlas (OC) by computed tomography (CT) imaging.
  
  
  METHODS
  We retrospectively reviewed 80 cases of patients with OC who underwent cervical CT scanning between March 2012 and March 2014. Forty healthy subjects were recruited as a control cohort. Fusion pattern and associated osseous anomalies were recorded. Fifteen linear quantitative parameters were measured to study the outlet of the foramen magnum, angular dimension of the skull base, posterior cranial fossa, and height of the odontoid process.
  
  
  RESULTS
  The most common fusion pattern was the complete osseous fusion (83.75%). Fifty-four patients (67.5%) presented with other osseous anomalies. Measurements of the OC group, such as the length of the clivus, cranial canal angle, and height of the odontoid process, were significantly different than those of the control group. The correlation analysis showed that the C1 lateral facet inclination was significantly correlated with the age of onset.
  
  
  CONCLUSIONS
  The outlet of the foramen magnum is severely impaired in patients with OC, and the presence of other osseous anomalies is common. Deformity is not confined to the region of the assimilated atlas; the clivus and odontoid process are also shorter than normal. The lateral facet inclination likely influences disease progression.
authors.affiliation: Department of Neurosurgery, PLA General Hospital, Beijing, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zong
authors.affiliation: Department of Neurosurgery, PLA General Hospital, Beijing, China.
authors.forename: Yiheng
authors.initials: Y
authors.lastname: Yin
authors.affiliation: Department of Neurosurgery, PLA General Hospital, Beijing, China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Qiao
authors.affiliation: Department of Neurosurgery, PLA General Hospital, Beijing, China.
authors.forename: Yazhou
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Neurosurgery, PLA General Hospital, Beijing, China. Electronic address: xinguang_yu@263.net.
authors.forename: Xinguang
authors.initials: X
authors.lastname: Yu
mesh_terms: D000328:Adult; D001269:Atlanto-Occipital Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D001270:Cervical Atlas / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019291:Skull Base / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Anatomy; Atlanto-occipital fusion; Atlas assimilation; Craniovertebral junction; Foramen magnum; Occipitalization