Swelling of the Muscles of the Shoulder Girdle in a CT Scan is a Leading Finding for the Diagnosis of Polymyositis

Polymyositis (PM) is an uncommon inflammatory disease of unknown cause, but the disease shares many characteristics with autoimmune disorders. In the past, the diagnosis criteria for PM depended primarily on clinical features, blood enzyme levels, an electromyogram, and muscle biopsies. However, there are still imperfections in the diagnostic criteria of PM. The development of muscle imaging led to revisiting not only the PM diagnosis strategy but also the patients' follow-up. Teaching point: PM should be considered and included in the differential diagnosis of a patient with inflammatory signs and muscular pain, and the radiologist should be aware of its imaging features.

Paralabral cysts of the shoulder treated with isolated labral repair: effect on pain and radiologic findings

BACKGROUND

Paralabral cysts emanating from posterosuperior labral tears may compress the suprascapular nerve and induce neuropathy. This study prospectively assessed patients with labral tears and symptomatic paralabral cysts treated with isolated labral repair. Pain relief, time to cyst resolution, reversibility of muscular edema, atrophy, fatty infiltration, and bone erosion were evaluated.

METHODS

Forty-seven patients with symptomatic posterosuperior paralabral cysts were treated with isolated labral repair. Magnetic resonance imaging (MRI) was repeated 6 and 12 weeks postoperatively or until cyst resolution. In a subgroup of 15 patients, MRI was performed the day before the operation, the first postoperative day, and at 2 weeks.

RESULTS

Median cyst size was 6.8 cm³ (range, 2.1-88.9; standard deviation [SD], 18.3 cm³). Preoperatively, 20 patients (43%) presented clinical muscle atrophy and radiologic edema on MRI, 8 had fatty infiltration, and 3 presented bony scapular erosion caused by cyst compression. Median time to cyst resolution and regression of muscular edema was 11 weeks (range, 3-20; SD, 8.8 weeks) and 14 weeks (range, 3-52; SD 10.6 weeks), respectively. Preoperative fatty infiltration grade I and II of the supraspinatus and infraspinatus muscles was reduced in two patients. Bony erosions remodeled after cyst resolution. Mean pain ratings (1-10 scale) improved from 7.7 (SD, 1.8) to 1.3 (SD, 1.3; 95% confidence interval of difference, 5.5-6.8; P < .001).

CONCLUSION

Labral repair leads to significant pain relief with cyst resolution within 2 to 3 months in most patients. Secondary muscle pathology (ie, edema, atrophy and fatty infiltration) may be partially or completely reversed. Bony erosion caused by cyst compression may be remodeled after cyst resolution.