Lateral subluxation of the atlanto-axial joint in rheumatoid arthritis.

Involvement of the cervical spine by rheumatoid disease is common, but lateral subluxation at the atlanto-axial level has not been recorded previously. The condition is due to asymmetrical erosion of the lateral atlanto-axial facet joint, and may be complicated by collapse of the lateral mass of the axis. The condition should be suspected in patients with rheumatoid arthritis (RA) who present with occipital, auricular, and/or facial pain.