Atlanto-axial instability in adults with Down's syndrome--a survey of a long-stay hospital population.

A survey was performed on the patients with Down's syndrome living in three long-stay hospitals for the mentally handicapped in Bristol. Each patient had a chromosomal analysis, lateral X-rays of the cervical spine in flexion and extension and subsequent measurement of the atlanto-odontoid distance, and a neurological examination. Out of a total of 59 patients, with ages ranging from 23 to 65 years (average age 48.27 years), three (5%) were found to be in the high risk category radiologically, but of these two were in the medium risk group on neurological examination and one low risk. Of five (8.5%) patients in the medium risk group on X-ray, four were in the medium risk group neurologically. Therefore a total of eight patients (13.6%) could be considered to be at risk of atlanto-axial instability.