Magnetic resonance imaging (MRI) showed that subacromial/subdeltoid bursitis is the most frequent shoulder lesion in polymyalgia rheumatica (PMR). We evaluated whether shoulder ultrasonography (US) was as effective as MRI in the detection of this lesion and assessed the sensitivity and specificity of bilateral subacromial/subdeltoid bursitis in the diagnosis of PMR.
A case-control study of 57 consecutive case patients with untreated PMR and 114 controls seen over a 6 month period in 3 secondary referral rheumatology centers. Control patients consisted of the next 2 consecutive patients with bilateral shoulder aching and stiffness observed after the case patient. In all case and control patients the glenohumeral joint space, bursae, and long head biceps tendon were assessed by bilateral shoulder US. The first 24 case patients were also examined by bilateral shoulder MRI.
US showed subacromial/subdeltoid bursitis in 55/57 (96%) patients with PMR and in 25/114 (22%) controls (p < 0.001). The lesion was bilateral in 53/55 (96%) case patients and in 1/25 (4%) controls (p < 0.001). The frequency of glenohumeral joint synovitis and biceps tenosynovitis did not differ significantly between case patients and controls. In 100% of case patients MRI showed subacromial/subdeltoid bursitis confirming US findings. The sonographic evidence of bilateral bursitis had a sensitivity of 92.9%, specificity of 99. 1%, and positive predictive value of 98. 1% for the diagnosis of PMR.
US and MRI were equally effective in confirming bilateral subacromial and subdeltoid bursitis in PMR. This finding, in view of its high sensitivity and specificity, could be used as a new diagnostic criterion for PMR.