Presentation
Right shoulder pain.
Patient Data
The posterior inferior labrum demonstrates irregular margin and ill-defined central high signal intensity suggestive of degenerative tear. In addition, a lobulated cystic lesion arising from the posterior inferior glenoid labrum tear is seen compatible with a paralabral cyst. The cyst is extending downward into the quadrilateral space resulting in mass effect on the axillary neurovascular bundle. There is muscle atrophy and fatty degeneration of the teres minor muscle without significant edema, consistent with chronic denervation changes. The constellation of findings are in keeping with quadrilateral space syndrome related to a paralabral cyst.
Thickening with mild intermediate T2 signal alteration is seen at the subscapularis, supraspinatus and infraspinatus tendons associated with small partial thickness tear of the posterior fibers of the supraspinatus tendon at the bursal surface. Os acromiale is noted. Osteoarthritic changes involving the right acromioclavicular joint are noted. Minimal fluid is seen in the subacromial, subdeltoid bursa suggestive of bursitis.
Case Discussion
This case demonstrates the typical denervation changes seen in quadrilateral space syndrome, although the axillary nerve provides motor innervation to teres minor and deltoid muscles, however, the deltoid muscle is sometimes spared.
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