A Retrospective Clinical and Neuroimmunohistochemical Study of Rheumatoid Arthritic Patients with Atlanto-Axial Subluxation

Abstract

In a retrospective study of 87 RA patients with radiographically documented anterior atlanto-axial subluxation (AAS) in flexion-extension radiographs, 40 had been studied radiographically before they developed AAS. Of these 40 patients, 34 had had occipitocervical pain already before the subluxation. This shows that pain early in the course of the rheumatoid cervical spine is not caused by or associated with AAS itself. In a separate operatively treated group of 5 patients, ligament neuroanatomy in AAS was more closely studied, using specific heteroantisera to cytoskeletal neurofilaments and various transmitter neuropeptides as neural markers and the highly sensitive avidin-biotin-peroxidase complex (ABC) immunohistochemical staining procedure. These specimens were obtained from the ligamentous structures between the posterior arch of the atlas and the spinous process of C2, corresponding to the C1-C2 interspinal non-inflammatory ligament, during atlanto-axial stabilizing operations. This ligamentous tissue contained, in addition to focal inflammatory cell infiltrates, neurofilament and/or neuropeptide immunoreactive neural elements. This finding may suggest that pain early in anterior AAS could be caused not only by synovitis, for example, but also by local ligamentary involvement leading to irritation of local neural elements. This phenomenon may have contributed to the local occipitocervical pain experienced by 34/40 patients who later developed AAS.

Key Words:

• cervical spine
• rheumatoid arthritis
• neurofilament
• neuropeptides