Rheumatoid arthritis in the cervical spine.

The cervical spine often becomes involved early in the course of rheumatoid arthritis, leading to three different patterns of instability: atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. Although radiographic changes are common, the prevalence of neurologic injury is relatively low. The primary goal of treatment is to prevent permanent neurologic injury while avoiding potentially dangerous and unnecessary surgery. Strategies include patient education, lifestyle modification, regular radiographic follow-up, and early surgical intervention, when indicated. Magnetic resonance imaging is indicated when neurologic deficit (myelopathy) occurs or when plain radiographs show atlantoaxial subluxation with a posterior atlantodental interval < or =14 mm, any degree of atlantoaxial impaction, or subaxial stenosis with a canal diameter < or =14 mm. Surgery should be considered promptly for any of the following: progressive neurologic deficit, chronic neck pain in the setting of radiographic instability that does not respond to nonnarcotic pain medication, any degree of atlantoaxial impaction or cord stenosis, a posterior atlantodental interval < or =14 mm, atlantoaxial impaction represented by odontoid migration > or =5 mm rostral to McGregor's line, sagittal canal diameter <14 mm, or a cervicomedullary angle <135 degrees.