Suprascapular nerve entrapment caused by supraglenoid cyst compression.

Twenty-two cases of suprascapular nerve entrapment caused by supraglenoid cyst compression were reviewed. Pain and weakness were the presenting symptoms in 14 shoulders and pain alone in 8. Twenty of the cysts were diagnosed by magnetic resonance imaging, and two were confirmed at surgical exploration. Electromyography of 20 shoulders was positive for neurologic involvement for both the infraspinatus and supraspinatus in 4 cases, for the infraspinatus only in 12, and negative in 4. Sixteen shoulders were treated by open excision, arthroscopy, or both. Superior labral lesions were diagnosed in 11 of 12 patients who underwent arthroscopy. At follow-up 10 of the patients who underwent surgery had complete resolution of symptoms, 5 had occasional pain or weakness, and 1 recurrence required a second surgery. Of six patients treated without surgery, two improved and four had no change. Supraglenoid ganglion cysts are common and can easily be diagnosed by magnetic resonance imaging. For patients with symptoms arthroscopy with repair of the superior labral lesion and either arthroscopic debridement or direct open decompression and excision of the cyst is recommended.