Manifestations of Cervical Spine Involvement in Longstanding Ankylosing Spondylitis: Atlantoaxial Ankylosis and Atlantoaxial Subluxation

Abstract

Objective. To analyze radiologic findings of cervical involvement in ankylosing spondylitis (AS) patients, determine its associationwith structural severity and clinical variables, and to divide radiologic findings of atlantoaxial ankylosis (AAA) in AS patientsinto three anatomical components. Methods. The study includes 150 AS patients with either AAA (62 patients) or atlantoaxialsubluxation (AAS, 88 patients) who underwent plain radiography of the cervical spine on flexion at our tertiary center for rheumaticdiseases. The study subjects’ medical records were reviewed. Lateral plain radiographs of the cervical spine were analyzedby a musculoskeletal radiologist. We compared the results of the modified Stoke Ankylosing Spondylitis Spinal Score(mSASSS) between AAS and AAA patients to determine if mSASSS was related to severity or duration of AS. Results. The meanduration of illness in AS patients with AAA was 19.3 years, and in AAS patients 13.7 years (p＜0.01). The mean total mSASSSof AS patients with AAA was 40.1, and of AAS patients 16.5 (p＜0.001), and was positively associated with the developmentof AAA and AAS. The odds ratio (OR) of AAA development by cervical spine mSASSS change was higher (OR, 1.079) than theOR (1.049) of lumbar spine mSASSS even after adjusting for age, sex, and disease duration. Conclusion. Although AAA is describedinfrequently, we found from our data that it is another manifestation of cervical spine involvement in longstanding ASand is related to severity of AS reflected by higher cervical mSASSS. (J Rheum Dis 2017;24:21-26)