Journal of the Canadian Chiropractic Association 1999 Dec;43(4): 229-35
A 21-year-old female presented to a chiropractic clinic with chronic neck and headache pain. She had an osseous torticollis and abnormal range of neck motion on rotation to the left. Radiographic examination revealed a unilateral paracondylar process of the occiput fusing to the lateral transverse process of the atlas. A paracondylar process is classified as an occipital vertebra. It is an enlarged bony process of the cranial base which projects caudally towards the transverse process of the atlas. She was treated with spinal manipulation below the level of fusion which resulted in a marked decrease in headache and neck pain. The embryology, frequency, radiographic appearance and clinical implications of a paracondylar process are discussed in this paper.