To investigate the frequency, location, characteristics, and clinical significance of subaxial involvement (below C1-C2) in a series of patients with rheumatoid arthritis (RA) and symptomatic involvement of the cervical spine.
A total of 41 patients with RA were examined via cervical spine magnetic resonance imaging (MRI). A comparative analysis of the incidence of the different types of subaxial lesions was performed between these patients and 41 age- and sex-matched patients with symptomatic cervical spondylosis.
Stenosis of the spinal canal was found at the subaxial level in 85% of RA patients, and at the atlantoaxial level in 44%. Comparative analysis between these patients and the cervical spondylosis patients revealed significant differences in the types and frequencies of subaxial lesions. For both conditions, signs of discopathy and end-plate osteophytosis were the most common abnormalities observed on magnetic resonance imaging (MRI). However, in the RA patients these abnormalities coincided with subchondral bone and ligamentous acute inflammatory changes and with secondary destruction (vertebral instability) or repair (vertebral ankyloses). Only evidence of subaxial myelopathy was significantly associated with an increased risk of neurological dysfunction among the RA patients [Ranawat class II or III; P = 0.01; odds ratio (OR) = 11.43], although subaxial cord compression tended toward a significant association with the risk of neurological dysfunction (P = 0.06; OR = 3.95).
Subaxial stenosis seems to be the consequence of both the inflammatory process and mechanical-degenerative changes. Despite its frequency, it was not usually related to the occurrence of myelopathy symptoms, not even in cases with MRI evidence of spinal cord compression.