Craniocervical abnormalities in Down's syndrome

Atlantoaxial Instability in down Syndrome-Guidelines for Screening and Detection

A community survey was conducted in all adults with Down syndrome living in three health districts to see if there was any correlation between radiological and neurological abnormalities which could indicate the presence of atlantoaxial instability. There was no difference in the proportion of individuals with neurological abnormalities in the group with radiological abnormalities suggestive of atlantoaxial instability (6/14) compared with individuals with normal X-rays (50/123) as determined by the chi square test (0.01463: not significant). The clinical and ethical implications for screening of people with Down syndrome living in the community are discussed in view of these findings.

Complications and long-term outcome of upper cervical spine arthrodesis in patients with Down syndrome

STUDY DESIGN

A retrospective review of 15 patients with Down syndrome who had undergone arthrodesis of the upper cervical spine for instability.

OBJECTIVES

To determine the complication rate and long-term outcome after posterior cervical arthrodesis for upper cervical instability in patients with Down syndrome.

SUMMARY OF BACKGROUND DATA

Atlantoaxial instability is common in patients with Down syndrome, and fusion of the upper cervical spine has been recommended for patients who have instability, with or without myelopathy. Unfortunately, the results of posterior cervical arthrodesis are not well reported, and the natural history of this condition is unknown.

METHODS

Fifteen patients with an average follow-up period of 74.6 months (range, 24-142 months) were reviewed after posterior arthrodesis of the upper cervical spine. Twelve patients were reexamined by the investigators specifically for the purpose of this study, and three patients had long-term follow-up results available from chart review.

RESULTS

Eleven of 15 patients (73%) sustained 23 major complications including nonunion, loss of reduction, neurologic deterioration, late subaxial instability, infection, and wound dehiscence. Six patients (40%) required seven reoperations to address a complication. Ultimately, 12 patients (80%) obtained osseous union, but a definite clinical improvement was identifiable in only three patients, whereas two others had worsened neurologically at latest follow-up evaluation.

CONCLUSIONS

A high complication rate should be anticipated after posterior arthrodesis of the upper cervical spine in patients with Down syndrome. A cautious approach to asymptomatic instability in this condition is advocated.

Occipitocervical fixation in nontraumatic upper cervical spine instability

Ten patients requiring occipitocervical fixation were reviewed: five were unstable secondary to rheumatoid arthritis, one had Klippel-Feil, and four had neoplastic disease. Patients with nonneoplastic disease improved, having decreased pain, decreased paresthesias, and increased ambulation. Patients with neoplastic disease improved significantly after the surgery, but eventually died from different tumors. The technique found to be most efficient was the placement of an intraoperatively contoured Luque rectangle wired from the occiput to appropriate cervical spine levels.

Perioperative spinal canal narrowing in patients with Down's syndrome

Two patients with Down's syndrome undergoing intracardiac operations had segmental and generalized myoclonic movements postoperatively and eventual brain death. Electroencephalography in 1 patient showed no seizure despite the presence of the myoclonic movements. Computed tomographic scan showed possible cerebellar hemorrhage. Ultrasound showed cerebral edema when the pupils became fixed and dilated. Because known postoperative neurologic complications could not fully explain the clinical course, and the myoclonic movements suggested spinal origin, we considered the possibility of atlantoaxial instability causing spinal cord damage related to perioperative head and neck positioning. Postmortem study on the second patient revealed 50% reduction of the spinal canal with hyperextension and 90-degree external rotation of the head and neck. In contrast, similar maneuvers in 3 infants without Down's syndrome resulted in only mild spinal canal narrowing. Although the myoclonic movements could be explained by spinal cord compression at the atlantoaxial level, the explanation for the eventual brain death is unclear. However, kinking of the vertebral arteries related to the positioning could have caused cerebellar ischemia, hemorrhage, and increased intracranial pressure. We believe that attention to the problem might bring further answers in the future.

Clinical predictors and radiological reliability in atlantoaxial subluxation in Down's syndrome

Clinical signs and symptoms that might predict atlantoaxial subluxation were studied prospectively in 135 of 180 children with Down's syndrome aged 6-14 years who form the Hester Adrian Research Centre cohort. Lateral radiographs of the cervical spine were taken in flexed, extended, and neutral positions, and the percentage of abnormalities in each view was 14, 10, and 10%, respectively. Gait was the only significant clinical predictor. The relative risk of having an abnormal neck radiograph with an abnormal gait was 2.91 (95% confidence interval (CI) 1 to 8). The sensitivity was 50% and the specificity 81%. Nineteen children had repeat radiographs to assess the reliability of radiological diagnosis. Six had abnormalities; five of 19 (26%) had an abnormality on the first radiograph, and four of 19 (21%) had an abnormality on a second radiograph, but only three (15%) had an abnormality on both occasions in any view (95% CI 0 to 25). We conclude that radiographs of the cervical spine are unreliable at identifying atlantoaxial subluxation in children with Down's syndrome, and we failed to identify any reliable clinical predictor.

Cervical spine injury masquerading as a medical emergency

Two cases of cervical spine fractures presenting as cardiac arrest in one case and as a coma with pneumonia and cervical osteomyelitis in the other are discussed. They demonstrate the need for careful history taking as well as a cautious approach to the cervical spine when accurate historical data are not available.

Atlantoaxial instability in adults with Down syndrome: a clinical and radiological survey

A survey of 129 adults with Down syndrome was undertaken to determine the prevalence of atlantoaxial instability (AAI) and to establish a base line for long term prospective study. Clinical and radiological evaluations were performed to determine optimal screening methods for this condition. The findings indicate that radiological evidence of AAI was found in 40% with anterior atlanto-odontoid distance (AAOD) of 3 mm or more and in 10% with 5 mm or more. These findings are similar to those reported in the pediatric age group. A preponderance of females with symptomatic AAI is noted. Clinical evaluation suggested the presence of spinal cord compression, which was confirmed by CT scan of the atlantoaxial region. There were no false negative clinical results. Among the false positive clinical findings other explanations were present in some cases. A comparison with the literature is offered along with guidelines on screening and management.