Eighty-four patients with Down syndrome had flexion-extension lateral roentgenograms of the C1-C2 articulation for the purpose of dividing the group into subluxators (> or = 4 mm atlanto-dens interval and 2 mm translation) and nonsubluxators (those who did not meet these criteria). Neurologic examinations and chart review were carried out on all patients to ascertain those with a positive neurologic finding or history. Seventeen (20%) were defined as subluxators and 67 (80%) as nonsubluxators. Five (29%) of the subluxators were found to have positive neurologic findings and 18 (27%) of the nonsubluxators had similar types of positive neurologic findings. These percentages are not significantly different. This led us to conclude that positive neurologic findings and an abnormal atlanto-dens interval are not alone adequate criteria to judge need for surgical stabilization of the C1-C2 articulation in patients with Down syndrome.
My Comment: The concern has always been what to do with the children and adults with AAI per Xray. According to this paper, the presence or absence of neurologic symptoms is not enough to diagnose spinal cord compression, and the presence of neurologic signs is not enough to warrant surgery. The authors advise that CAT scans or MRIs be done of the neck, including flexion and extension views, before surgery is attempted.
There is an ongoing study at the Cincinnati Center for Developmental Disorders looking at the use of MRIs to further determine the best way to diagnose AAI.
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