Symptomatic atlantoaxial instability in Down syndrome

Abstract

The aim of this study was to audit the treatment of symptomatic atlantoaxial instability in Down syndrome and to assess factors associated with fusion failure in this group of patients. The authors reviewed the cases of 12 children with Down syndrome presenting with symptomatic atlantoaxial instability who underwent surgery for internal fixation and fusion. A review of clinical histories, radiological investigations, and details of operative interventions was also performed. The mode of presentation was acute spinal cord injury (five cases), progressive myelopathy (four cases), and neck pain or stiffness (three cases). The atlantodental interval ranged from 5 to 13 mm. The posterior atlantodental interval at the C-1 level was 9.5 mm (range 6-11 mm). In 10 patients an os odontoideum was present. Translocation of the odontoid process occurred in one patient, and occipitoatlantal instability was also identified in two cases. Twenty-four operations were performed in the 12 patients. A transoral odontoidectomy was required in four children. Successful fusion was demonstrated in seven patients at the first operation. Three of the five patients with acute cord injury made significant functional recovery and were left with no or mild disability. Additional bone abnormalities at the CVJ are common in the Down syndrome population. Young age at the time of fusion and multiple osseous anomalies pose a higher risk factor in fusion failure. The authors recommend an aggressive surgical approach for management of symptomatic cases of CVJ instability.