Atlanto-axial dislocation in Down's syndrome. Report of two cases requiring surgical correction.

Two cases of symptomatic atlanto-axial dislocation in association with Down's syndrome are reported. The first patient showed spinal cord compression and had an ossiculum terminale; the second showed neck pain and had anteriorly inclined facet joint of the axis. Complete reduction was not obtained in either case. Both patients were treated successfully by posterior fusion of C1 and C2 in the maximally obtained position of reduction. In cases of symptomatic atlanto-axial dislocation when the spinal cord is at risk, surgical stabilization is the treatment of choice.