• Journal of Korean Neurosurgical Society
• /
• v.29 no.3
• /
• pp.402-406
• /
• 2000

The term 'craniovertebral junction' refers to the occipital bone that surrounds the foramen magnum and the atlas and the axis vertebrae. A wide variety of congenital, developmental, and acquired anomalies exist at the craniovertebral junction. The authors present a rare case of the congenital anomaly of the craniovertebral junction consisting of atlantal hypoplasia, atlantal assimilation, and basilar invagination in a 58-year-old male. An occiput-C2 arthrodesis was performed. The clinical and imaging features are described, and the embryology and etiology of this anomaly are discussed.

• Journal of Korean Neurosurgical Society
• /
• v.58 no.6
• /
• pp.528-533
• /
• 2015

Objective : We sought to examine anatomic variations of the atlas and the clinical significance of these variations. Methods : We retrospectively reviewed 1029 cervical 3-dimensional (3D) CT images. Cervical 3D CT was performed between November 2011 and August 2014. Arcuate foramina were classified as partial or complete and left and/or right. Occipitalization of the atlas was classified in accordance with criteria specified by Mudaliar et al. Posterior arch defects of the atlas were classified in accordance with criteria specified by Currarino et al. Results : One hundred and eight vertebrae (108/1029, 10.5%) showed an arcuate foramen. Bilateral arcuate foramina were present in 41 of these vertebrae and the remaining 67 arcuate foramina were unilateral (right 31, left 36). Right-side arcuate foramina were partial on 18 sides and complete on 54 sides. Left-side arcuate foramina were partial on 24 sides and complete on 53 sides. One case of atlas assimilation was found. Twelve patients (12/1029, 1.17%) had a defect of the atlantal posterior arch. Nine of these patients (9/1029, 0.87%) had a type A posterior arch defect. We also identified one type B, one type D, and one type E defect. Conclusion : Preoperative diagnosis of occipitalization of the atlas and arcuate foramina using 3D CT is of paramount importance in avoiding neurovascular injury during surgery. It is important to be aware of posterior arch defects of the atlas because they may be misdiagnosed as a fracture.