Rheumatoid Arthritis (ICD-9 720.0)
- Up to 71% of patients with rheumatoid arthritis have C-spine involvement.
- C1-C2 instability, basilar invagination, and subaxial subluxation are common disease patterns.
- Inflammatory pannus causes synovial joint destruction.
- Eighty percent of patients are rheumatoid factor positive.
Rheumatoid arthritis is the most common form of inflammatory arthritis. It affects 3% of women and 1% of men. The disease frequently affects the spine. Up to 71% of patients with rheumatoid arthritis show involvement of the cervical spine. The most common patterns of involvement are C1-C2 instability, basilar invagination, and subaxial subluxation (ICD-9 738.4). Of these patterns, both C1-C2 instability and basilar invagination have become less frequently encountered as a result of improvements in pharmacologic therapy. Sudden death associated with rheumatoid arthritis, most probably secondary to brainstem compression or vertebrobasilar insufficiency, is reported.
The same inflammatory cells that destroy peripheral joints affect the synovium of apophyseal and uncovertebral joints of the spine, causing painful instability with or without neurologic compromise. The pannus, a conglomeration of hypertrophic synovium and inflammatory cells, often causes facet joint and transverse ligament destruction, leading to painful instability. The hypertrophic tissue can also cause direct compression of the spinal cord and nerve roots at the affected levels.
Prevention of rheumatoid instability centers around control of the inflammatory component of the disease. The standard pharmacotherapeutic strategy initially involves the use of anti-inflammatory medication and ends the application of DMARDs.
From 7 to 34% of patients present with neurologic problems. Documentation of neurologic function can be difficult because loss of joint mobility leads to general muscle weakness. Although many patients complain of nonspecific neck pain, atlantoaxial subluxation is the most common cause of pain in the upper neck, occiput, and forehead in patients with rheumatoid arthritis. Symptoms are aggravated by motion. Increasing compression of the spinal cord results in severe myelopathy with gait abnormalities, weakness, paresthesias, and loss of dexterity. Findings may also include Lhermitte sign (a tingling or electrical feeling that occurs in the arms, legs, or trunk when the neck is flexed), increased muscle tonus of the upper and lower extremities, and pathologic reflexes.
Instability of the upper cervical spine is determined on lateral flexion-extension radiographs. An atlantodens interval (ADI) that exceeds 3.5 mm is abnormal. Subluxation with an ADI of 10–12 mm indicates disruption of all supporting ligaments of the atlantoaxial complex (transverse and alar ligaments). The spinal cord in this position is compressed between the dens and the posterior arch of C1. Although the ADI is an important measurement for traumatic instability of the C1-C2 complex, the posterior atlantodens interval (PADI) is ...