title: Two year followup of anterior and vertical atlantoaxial subluxation in ankylosing spondylitis.
abstract: OBJECTIVE
  To describe the clinical and radiological 2-yr followup of 22 patients with anterior atlantoaxial subluxation (AAS) from a prospective cohort of patients with ankylosing spondylitis.
  
  
  METHODS
  The 2-yr assessment included a structured questionnaire for rheumatologic and neurologic complaints and lateral cervical radiographs in maximal flexion view. Initial and 2-yr radiographs were assessed blind to patient data. The course of anterior AAS was classified as unchanged (< 1 mm), progression (> or = 1 mm) or regression (> or = 1 mm) at 2 yrs compared with baseline. Vertical AAS was classified using the Sakaguchi-Kauppi method. Magnification factor was corrected using the ratio of C3 width.
  
  
  RESULTS
  Anterior AAS was detected in 22 patients at baseline examination. Two patients also had vertical AAS; 86% were male. Mean age was 33 +/- 9 yrs and mean disease duration was 12 +/- 7 yrs. At followup, one patient had died of acquired immunodeficiency syndrome, 3 could not be reached, and 2 had undergone surgical fusion due to severe myelopathy and now showed complete neurological recovery. Of the remaining 16 patients, 7 (32%) showed progression and 9 (41%) showed no change in the C1-odontoid distance. Vertical AAS developed in one patient. After the 2-yr assessment, 3 additional patients had surgical fusion because of notable progression of AAS, despite absence of neurological signs.
  
  
  CONCLUSIONS
  Anterior AAS progressed in a number of these patients in the 2 yrs following its detection, and with or without neurological signs, surgical management was thought appropriate in a considerable number of them.
authors.affiliation: Department of Rheumatology, Hospital de Especialidades del Centro Medico Nacional de Occidente, IMSS, Guadalajara, Mexico.
authors.forename: C
authors.initials: C
authors.lastname: Ramos-Remus
authors.forename: A
authors.initials: A
authors.lastname: Gomez-Vargas
authors.forename: A
authors.initials: A
authors.lastname: Hernandez-Chavez
authors.forename: J I
authors.initials: JI
authors.lastname: Gamez-Nava
authors.forename: L
authors.initials: L
authors.lastname: Gonzalez-Lopez
authors.forename: A S
authors.initials: AS
authors.lastname: Russell
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000293:injuries*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D004204:Joint Dislocations / Q000150:complications / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013117:Spinal Cord Compression / Q000209:etiology; D013167:Spondylitis, Ankylosing / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology