Atlantoaxial Instability in Down Syndrome: Subject Review

Abstract

DEFINITION OF THE PROBLEM In 1984, the American Academy of Pediatrics (AAP) published a position statement on screening for atlantoaxial instability (AAI) in youth with Down syndrome.1 In that statement, the AAP supported the requirement introduced by the Special Olympics in 1983 that lateral neck radiographs be obtained for individuals with Down syndrome before they participate in the Special Olympics' nationwide competitive program for developmentally disabled persons. Those participants with radiologic evidence of instability are banned from certain activities that may be associated with increased risk of injury to the cervical spine. This policy seemed to be prudent in light of the information available at that time. However, the AAP Committee on Sports Medicine and Fitness recently has reviewed the data on which this recommendation was based and has decided that uncertainty exists concerning the value of cervical spine radiographs in screening for possible catastrophic neck injury in athletes with Down syndrome. The 1984 statement therefore has been retired. This review discusses the available research data on this subject. BACKGROUND AAI, also called atlantoaxial subluxation, denotes increased mobility at the articulation of the first and second cervical vertebrae (atlantoaxial joint). This condition is found not only in patients who have Down syndrome but also in some patients who have rheumatoid arthritis, abnormalities of the odontoid process of the axis, and various forms of dwarfism.1 The causes of AAI are not well understood but may include abnormalities of the ligaments that maintain the integrity of the C-1 and C-2 articulation, bony abnormalities of C-1 or C-2, or both.1-11