Management of congenital atlanto-axial dislocation: some lessons learnt

Congenital atlantoaxial dislocation (AAD) has a high incidence in India. In these patients, even a minor trauma may precipitate severe morbidity. The management of mobile AAD consists of posterior stabilization. In fixed AAD, the offending compressive element is present anterior to the cervicomedullary junction, which should be generously removed by the transoral approach. In many of these patients, the assimilated posterior arch of atlas or the incurving posterior margin of the foramen magnum or associated Chiari I malformation also adds to the compromise of the canal diameter at the foramen magnum. Thus, in cases of fixed AAD, the hour glass appearance of the spinal canal at the craniovertebral junction should be converted into a funnel shaped appearance which is close to normal. Since these procedures require a generous removal of the osteoligamentous structures, posterior fusion should be done in all cases after decompressive surgery. In this review, the observations that emerged during the management of congenital AAD are presented with a special focus on the assessment scales modified to the Indian settings, hypermobile AAD, rotary C1-2 dislocation, and AAD associated with Chiari I malformation and syringomyelia.