Glen lesion ganglion cyst arising from the superior Labrum with entrapment of the inferior branch of the suprascapular nerve. Suprascapular nerve entrapment can be caused by: direct or indirect trauma or dislocation, entrapment beneath the superior transverse scapula ligament at the suprascapular notch, compression by osteochondroma or malignant tumor, and compression by ganglion cyst. Ganglion cyst arises from the posterior-superior glenoid labrum.
Cause of the cyst has not yet been clearly defined, but the underlying pathology seems to be a labral tear, especially posterior type II SLAP lesions. Entrapment by ganglion cyst can lead to weakness and wasting of the infraspinatus muscle. The clinical significance of a glen lesion is the weakness and wasting of the infraspinatus muscle.