Radiographic study of the upper cervical spine in the 22Q11.2 deletion syndrome

Background: The chromosome abnormality, deletion of 22q11.2, is one of the most common genetic syndromes. The 22q11.2 deletion syndrome encompasses a wide spectrum of abnormalities including cardiac, palate, and immunological anomalies. The purposes of the current study were (1) to define and determine the frequency of variations of the occiput and cervical spine on plain radiographs in patients with the 22q11.2 deletion syndrome and (2) to postulate the potential clinical importance of these variations. Methods: Seventy-nine consecutive patients with the 22q11.2 deletion underwent clinical and radiographic evaluation of the occiput and cervical spine. Radiographic studies included lateral plain radiographs of the cervical spine in neutral, flexion, and extension; anteroposterior radiographs; and open-mouth odontoid radiographs. Results: At least one developmental variation of the occiput or cervical spine was observed in every patient. The occipital variations were platybasia in fifty-two (91%) of the fifty-seven patients for whom data were available and basilar impression in two (3%) of the seventy-nine patients. The atlas variations were dysmorphic shape in fifty-nine (75%) of the seventy-nine patients, open posterior arch in forty-seven (59%) of the seventy-nine patients, and occipitalization in two (3%) of the seventy-one patients with adequate radiographs. The axis variations were dysmorphic dens in forty-six (58%) and upswept lamina and posterior elements or "C2 swoosh" in forty-seven (59%) of the seventy-nine patients. Of the seventy-one patients with adequate radiographs, twenty-four (34%) had fusion of C2-C3, fifteen (21%) had fusion of the posterior elements only, and nine (13%) had a complete block fusion. Increased segmental motion was observed in forty (56%) of the seventy-one patients. Thirteen (33%) of the forty patients had increased segmental motion at more than one level. Thirty-one patients (44%) had increased occipitoatlantal motion, seven (10%) had increased atlantoaxial motion, and four had increased C2-C3 motion. Eleven (15%) of the seventy-one patients had increased C3-C4 mobility, always adjacent to a fusion of C2-C3. Conclusions: Variations of the upper cervical spine, including increased segmental motion, are common in the 22q11.2 deletion syndrome. It is premature to predict the clinical implications of these radiographic findings, but advanced imaging and further observation may be needed to clarify their clinical course.