Manifestations of rheumatoid arthritis: epidural pannus and atlantoaxial subluxation resulting in basilar invagination.

Presented in part at the AAPMR 71st Annual Assembly Meeting, Seattle, WA, November 4-7, 2010. Atlantoaxial instability results from cartilaginous destruction, periarticular erosions, and ligament and tendon attenuation. Instability affects 19%-70% of patients, and basilar invagination from vertical odontoid subluxation through the foramen magnum occurs in 38% of patients. This phenomenon occurs twice as often in women than men, whose age at diagnosis typically ranges from 30-50 years. Along with bony compression, the pannus further decreases the space available for the cord by 3mmor more in approximately 66% of patients (Figures 1-7). The earliest and most common symptom of cervical subluxation is pain radiating up into the occiput with associated headaches. Episodes of medullary dysfunction that represent severe but less common patterns of progressive myelopathic symptoms provide an even more grim prognosis. When cervical myelopathy is established, 50% of these patients die within 1 year