Summary
Background: Rachischisis is an uncommon congenital abnormality of the spinal column. Its occurrence rate is thought to be approximately 4%. Cases of rachischisis are diagnosed either incidentally or
secondary to neurologic dysfunction.
Case Report: We report the case of a 33-year-old woman who presented status post motor vehicle vs. pedestrian accident. She reported neck, back and right elbow pain. CT scan of her cervical spine revealed an occipital assimilation of C-1 and a rachischisis of the anterior and posterior arch of C-1.
Conclusions: To our knowledge, a patient with occipital assimilation of the atlas with an associated rachischisis of the anterior and posterior arches of the atlas has not been reported in the literature.

Keywords: Rachischisis, occipitalization of the atlas, cervical spine anomaly