Atlantoaxial Instability In Down's Syndrome Research Articles

Symptomatic atlantoaxial instability in Down syndrome

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.

Commentary: atlantoaxial instability in Down syndrome: reassessment by the Committee on Sports Medicine and Fitness of the American Academy of Pediatrics.

Commentary: atlantoaxial instability in Down syndrome: reassessment by the Committee on Sports Medicine and Fitness of the American Academy of Pediatrics.

Posterior spinal arthrodesis for atlantoaxial instability in Down syndrome.

Nine children with Down syndrome who had atlantoaxial instability underwent posterior spinal fusion. At follow-up, all patients had stabilization or improvement of their neurologic symptoms. Evaluation of the spine using flexion and lateral radiographs, as well as selective cineradiography, showed no instability over the fused area or adjacent motion segments. Stable fibrous union with no clinical significance was noted in three of the nine patients. We recommend posterior spinal fusion in situ with external immobilization as the safest and most effective means of surgical stabilization in the patient with Down syndrome who has symptomatic atlantoaxial instability.

Atlantoaxial Instability in Down Syndrome: Subject Review

This Policy Statement was retired February 2008. 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

Neurologic sequelae secondary to atlantoaxial instability in Down syndrome. Implications in otolaryngologic surgery.

A comprehensive overview of atlantoaxial instability in Down syndrome as it relates to head and neck surgery and recommendations as derived from a review of the literature. English-language literature: otolaryngologic problems in Down syndrome and atlantoaxial biomechanics. Children affected with Down syndrome frequently require otolaryngologic procedures such as myringotomy with ventilation tubes or adenotonsillar surgery. Atlantoaxial instability occurs in 10% to 20% of patients with Down syndrome who are at risk for atlantoaxial subluxation and subsequent complications during anesthetic induction and during positioning and manipulation associated with surgery. To identify patients who are at risk for atlantoaxial subluxation, guidelines have been adapted from the recommendations of the American Academy of Pediatrics and the Special Olympics Inc, which include preoperative neurologic assessments and cervical roentgenograms in the neutral, flexion, and extension positions. Children with an atlantodental interval of greater than 4.5 mm or with peripheral neurologic findings should have further evaluation. A small percentage of patients with Down syndrome are at risk for atlantoaxial instability and subluxation. All patients with Down syndrome should have a preoperative neurologic assessment screening by the operating surgeon and/or a cervical roentgenogram in the lateral, extension, and flexion positions. Any abnormality should be investigated before surgery.

Symptomatic Atlantoaxial Instability Associated With Medical and Rehabilitative Procedures in Children With Down Syndrome

The Canadian College of Medical Genetics recently questioned the rationale for radiographic screening for atlantoaxial instability in Down syndrome. We report a case series of four children with Down syndrome with symptomatic atlantoaxial instability and followed for more than 5 years. In all cases a medical or rehabilitational procedure was associated with significant apnea, cardiopulmonary compromise, or severe neurological impairments. None of these patients were screened radiographically. The need for protocols to detect atlantoaxial instability in children with Down syndrome undergoing medical and rehabilitational procedures is highlighted by these cases.

Atlantoaxial instability in Down syndrome: Roentgenographic, neurologic, and somatosensory evoked potential studies

To identify patients with Down syndrome and asymptomatic atlantoaxial instability who are at increased risk for developing neurologic symptoms, we studied 27 patients with this skeletal disorder and compared them with an age- and sex-matched group of 27 patients with Down syndrome without atlantoaxial instability. A third group of six patients had symptomatic atlantoaxial instability. The mean atlanto-dens intervals and the mean spinal canal widths among the three groups were significantly different. There were no significant differences in mean composite neurologic scores and somatosensory evoked responses between patients in the asymptomatic group and those in the control group. However, when a subsample of patients with high and low latencies (greater than 1 SD below and above the mean) was formed and comparisons were made with roentgenographic findings, there was a high correspondence between somatosensory evoked potential latencies and atlanto-dens interval measurements. We conclude that no single assessment technique, but a combined approach using roentgenographic, CT scan, neurologic, and neurophysiologic investigations, will provide information of the risk status of patients with Down syndrome and atlantoaxial instability.

Chronic atlanto-axial instability in Down syndrome.

We studied the radiographs of thirty-two patients with Down syndrome for evidence of atlanto-axial instability. One of the patients had instability in 1970 and seven had it in 1983. The interval between the atlas and the odontoid process in the patients who demonstrated motion at that interval radiographically averaged 2.78 millimeters in 1970 and 6.93 millimeters in 1983 (p less than 0.005). Four patients whose radiographs showed atlanto-axial motion in 1970 lost that motion by 1983, and in seven patients who did not show atlanto-axial instability in 1970 it developed by 1983. Atlanto-axial instability was more likely to develop in boys who were more than ten years old. Accessory upper-cervical ossicles became evident in three patients, none of whom had atlanto-axial motion. However, one of these three patients had an abnormally wide atlanto-axial interval.