Prevalence of atlanto-occipital and atlantoaxial instability in adults with Down syndrome.

OBJECTIVE: This study sought to evaluate the presence of atlanto-occipital and atlantoaxial instabilities as well as their clinical significance in patients with Down syndrome.

METHODS: The present study retrospectively evaluated 80 adults with Down syndrome for the presence of atlanto-occipital and atlantoaxial instability in lateral craniocervical radiographic images. Atlanto-occipital instability was defined by the Rules of 12 or Harris measurements, using the values of the basion-dens interval or the basion-axial interval. Atlantoaxial instability was radiologically identified by the space between the anterior border of the odontoid apophysis and the posterior border of the atlas arch, as well as by the Wiesel-Rothman line.

RESULTS: Eighty patients were assessed; 14 (17.5%) presented with atlanto-occipital instability and 9 (11.2%) with atlantoaxial instability. Only 3 patients (3.8%) had specific symptoms for cervical instability. There was no statistical correlation with patient age or gender.

CONCLUSIONS: High cervical instability in patients with Down syndrome can also be observed among adults, and there is a low correlation between the radiological findings and symptoms. These findings emphasize the importance of periodic follow-up on these patients, particularly when sports activities are considered.