umls-concept:C1846439 | skos:definition | NCI: An often asymptomatic developmental abnormality of the cervical spine. It is characterized by the hypoplasia of the odontoid which appears as a stubby peg of an odontoid process. Symptoms may develop after minor trauma and include localized neck pain, atlantoaxial instability, and transient or permanent neurologic manifestations. | lld:umls |