Abstract
Congenital defects of the posterior arch of the atlas are very rare. In this study, we investigated seven patients with congenital defects of the posterior arch of the atlas. The mean patient age was 47.5 years (range, 16 to 64 yr). All patients complained of neck pain. According to the classification of Currarino, four cases were classified as Type A, two as Type B, and 1 as Type E. The symptoms in the Type A and Type B patients subsided after conservative treatment. The Type E case (complete defect) showed myelopathy due to atlanto-axial instability caused by co-existing os-odontoideum, and the patient underwent posterior occipito-C4 fixation with pedicle screws. After the operation, the neck pain disappeared and the symptoms of the myelopathy improved. Most cases of congenital defects of the posterior arch of the atlas are found incidentally by roentgenographic or computed tomographic examinations for neck pain. We suggest that congenital defects of the posterior arch of the atlas be considered in differential diagnosis of patients with neck pain.
