Duplicated odontoid process

Abstract: Duplication of the odontoid process remains a rare developmental pathology that is underrepresented in the current literature. As the pivot point for the craniovertebral junction, the odontoid process is vital for the integrity of the atlanto-axial joint and the ability of the head and cervical spine to rotate correctly. The pathogenesis being incompletely understood, it has been proposed that odontoid process duplication involves faulty sclerotome migration and disruption of the axis ossification center. Patients presenting with this pathology usually have associated structural abnormalities. A detailed anatomical and embryological understanding of the odontoid process is necessary for successful management and treatment of patients presenting with odontoid process duplication. We present a rare case of a patient with a duplicated odontoid process in association with C2-C3 fusion, incomplete anterior arch of C1, variant inferior bony process of the transverse process of C1, and enlarged right jugular foramen.

Abstract: The odontoid process was once thought to be a displaced body of the atlas but is now believed to have separated from the anterior part of the atlas between the sixth and seventh week of gestation and to have migrated caudally to fuse with the body of the axis. The fully formed odontoid process is toothlike/peg shaped with a curved superior surface and deviates slightly to the left or right in approximately 14–26% of the population. The odontoid may also be retroflexed, and this has been found to be more common in individuals with the Chiari I malformation.