To investigate the frequency and clinical significance of bone marrow edema (BME) in a series of patients with rheumatoid arthritis (RA) and symptomatic involvement of the cervical spine.
We studied 19 consecutive RA patients with cervical spine magnetic resonance imaging (MRI) according to a specifically designed protocol that included short inversion time inversion recovery sequences. All cases had neck pain unresponsive to conventional treatment, neurological symptoms, or signs suggestive of cervical myelopathy, or cervical pain with evidence of atlantoaxial subluxation on radiographs.
The mean age of the 19 patients (15 women and 4 men) at time of the study was 59 +/- 12 years (range, 23-82) and the median disease duration was 14 +/- 7.4 years (range, 4-30). BME was observed in 74% (14/19) of the patients: at the atlantoaxial level alone in 16% of the patients; subaxially alone in 16%; and at both levels in 42% of the patients. At the atlantoaxial level, BME was usually observed involving the odontoid process, whereas subaxially BME was limited to the vertebral plates and the interapophyseal joints. Patients with BME had higher erythrocyte sedimentation rate (ESR) values at the time of MRI examination (P = 0.014) and more severe atlantoaxial joint MRI synovitis scores (P = 0.05) compared with the remaining patients; the frequency of odontoid erosions was also greater in this group, but the difference did not reach statistical significance. Altogether, these data suggest a more severe inflammatory response in these patients. In this group a significant correlation was found between BME scores at atlantoaxial level and (1) ESR values (r = 0.854; P = 0.001) and (2) atlantoaxial joint MRI synovitis scores (r = 0.691; P = 0.001).
BME is frequently observed in patients with established RA and symptomatic cervical spine involvement. Both atlantoaxial and subaxial levels are equally affected. The presence of BME seems related to the intensity of the inflammatory response and to the severity of the atlantoaxial joint synovitis.