Os odontoideum is a relatively common developmental anomaly of the craniovertebral junction (CVJ), which is usually an incidental finding on spine imaging. But the dystopic variety of os odontoideum is uncommon and can be baleful. This anomaly can be a cause of atlantoaxial instability requiring surgical fixation. But the diagnosis of this variety requires considerable knowledge of anatomy of the CVJ as this unfamiliar entity needs to be differentiated from other CVJ anomalies like persistent os terminale, accessory ossicle of anterior arch of atlas, assimilation of atlas, and, most importantly, from orthotopic variety of os odontoideum. Here, we present a 34-year-old lady who presented with gradual-onset weakness of right side of the body. A computed tomography scan of the cervical spine revealed dystopic os odontoideum.
Keywords: Cervical atlas, Congenital abnormalities, Joint instability, Odontoid, Spine.
How to cite this article: Das JM, Krishnakumar K, Nair S. Dystopic Os Odontoideum: A Rare Cause of Atlantoaxial Instability. J Spinal Surg 2017;4(1):38-39.
Source of support: Nil
Conflict of interest: None