Chronic Atlanto-axial Instability in the Down Syndrome

The atlanto-axial segments of the cervical spine in children with the Down Syndrome have a predilection for the development of localized anomalies which are of particular interest, because of the danger of atlanto-axial dislocation [4, 6, 7, 13, 18, 23, 27, 28, 31]. All previous studies are limited by the fact that they are not longitudinal [17, 18, 26, 29]. They only describe the incidence of the abnormalities in the Down Syndrome in a population and do not attempt to study the natural history of either the anomalies or the C1–C2 instability.