LIGAMENTOUS LAXITY and craniocervical abnormalities are well-known features of Down syndrome (DS).1 The excess mobility of the articulation of the atlas (C1) and axis (C2) has been termed atlantoaxial instability (AAI). It is estimated that 2% of individuals with DS have symptoms of spinal cord compression because of this instability. Such individuals usually have neurologic signs and symptoms ranging from neck pain, torticollis, change in gait, change in bowel or bladder control, hyperreflexia, and presence of Babinski sign to quadriparesis and quadriplegia. They require urgent evaluation and management (which may include cervical spine fixation). On the other hand, approximately 13% of individuals with DS have evidence of excess movement of the joint between C1 and C2 but are asymptomatic. The concern that these individuals might be at risk of spinal cord injury has had widespread ramifications.
Cohen WI. Atlantoaxial InstabilityWhat's Next?. Arch Pediatr Adolesc Med. 1998;152(2):119-122. doi:10.1001/archpedi.152.2.119