MR imaging and MR arthrography of paraglenoid labral cysts

OBJECTIVE. We investigated the pathophysiology of paraglenoid labral cysts on the basis of MR imaging, MR arthrography, and cyst aspiration. MATERIALS AND METHODS. From 2211 MR imaging examinations, 51 (2.3%) cysts i n 46 patients were identified. MR arthrography (n = 5), cystography (n = 1) , arthroscopy (n = 17), percutaneous needle aspiration (n = 4), and medical records were also reviewed (n = 46). RESULTS. On MR imaging and arthrography, cysts were best viewed on T2-weigh ted images. Mean cyst diameter and volume were 2.2 cm and 2.8 cm(3), respec tively. Fifty-seven percent of cysts were located adjacent to the posterior labrum. On MR imaging and arthroscopy, a labral tear was identified in 27 (53%) and 15 (88%) patients, respectively. Eight cysts that caused compress ion neuropathy were large (mean size, 3.1 cm; p = 0.04) and located next to the posterior or inferior labrum. In four of five patients, MR arthrograms showed no intraarticular contrast material in the cyst. Cystograms showed no communication with the glenohumeral joint space, and cyst aspiration res ulted in temporary symptom relief; however, cysts recurred in three of four patients. CONCLUSION. Most paralabral cysts are associated with labral tears. Paralab ral cysts may be difficult to identify on MR arthrography unless a T2-weigh ted sequence is performed. Direct communication between a cyst and joint sp ace rarely occurs. A posterior or inferior cyst may cause compression neuro pathy of the suprascapular or axillary nerve, respectively. Cyst aspiration may result in temporary relief of symptoms, but an untreated labral tear s hould be suspected if cysts recur.