Atlantoaxial Instability in Down Syndrome

Abstract

Some issues related to participation in certain sports by persons with Down syndrome require clarification. Since 1965 there have been occasional reports about a condition described at various times as instability, subluxation, or dislocation of the articulation of the first and second cervical vertebrae (atlantoaxial joint) among persons with Down syndrome.1-15 This condition has also been found in patients with rheumatoid arthritis,16,17 abnormalities of the odontoid process of the second cervical vertebra,4,5,12,13,15 and various forms of dwarfism.18 Atlantoaxial (C-1, C-2) instability has not attracted general attention because clinical manifestations are rare and the condition is limited to a small portion of the population. The incidence of atlantoaxial instability among persons with Down syndrome has been reported by various observers to be 10% to 20%.2,9,15 When atlantoaxial instability results in subluxation or dislocation of C-1 and C-2, the spinal cord also may be injured. This is a rare but serious complication. In March 1983, the Special Olympics, Inc, sponsors of a nationwide competitive athletic program for developmentally disabled persons, without prior announcement, mandated for participants with Down syndrome special precautions to prevent serious neurologic consequences from stress on the head and neck in sports competition.19 Although thousands of persons with Down syndrome have taken part in sports events during the 15-year history of the Special Olympics without a known occurrence of neurologic complications due to participation, the new directive requires all persons with Down syndrome who wish to participate in certain sports that might involve stress on the head and neck (gymnastics, diving, pentathlon, butterfly stroke in swimming, diving start in swimming, high jump, soccer, and warm-up exercises that place undue stress on the head and neck muscles) to have a medical examination, lateral-view roentgenograms of the upper cervical region in full flexion and extension, and certification by a physician that the examination did not reveal atlantoaxial instability or neurologic disorder.