Occipitalization of Atlas: A case report.

Occipitalization of atlas is an osseous anomaly of the cranio-vertebral junction which occurs at the base of the skull in the region of the foramen magnum due to failure of segmentation and separation of the most caudal occipital sclerotome and the first cervical sclerotome during the first few weeks of foetal life. Atlas is the first cervical vertebra and the atlanto-occipital joint belongs to ellipsoid variety of synovial joints. It does not have a body like other vertebrae. Rarely, it gets occipitalized, where the lateral masses of the atlas vertebra fuse with the condyles of the occipital bone. One skull showing Occipitalization of Atlas was observed in the Department of Anatomy, B.J. Medical College, Ahmedabad, Gujarat. The knowledge of such a fusion may be of importance for radiologists, anaesthesiologists, orthopaedic and neurosurgeons because skeletal abnormalities at the cranio-cervical junction may result in sudden unexpected death. It can result in dysphagia, dysarthria or torticollis because of compression of cranial nerves. They should be aware that such an anomaly may exist without any typical symptomatic presentation, and thus, serious consequences of upper cervical spinal manipulative therapy may arise when a complete and adequate clinical assessment is missed.