Abstract
Spontaneous dislocation of the atlanto-axial joint is a frequent occurrence in Down's syndrome. Atlanto-axial dislocation was observed in 25 out of 135 subjects ranging in age from 2 to 47 years. The incidence of dislocation appears to be more frequent in Down's syndrome with the advancement of age. Out of 25 patients with dislocation, 4 had an ossiculum terminale and hypoplastic odontoid, 2 had third condyle, 5 had agenesis of apical segment of the odontoid, and one had a bassilar process. It was thought that the cause of dislocation in the remaining 13 patients was due to abnormality of the transverse atlantal ligament. A dislocation associated with cervical cord compression was observed in two cases. One child was treated by laminectomy for decompression, and another, who showed compression signs of cervical cord, spontaneously improved.
