Suprascapular nerve entrapment isolated to the spinoglenoid notch: surgical technique and results of open decompression.

Background: Entrapment of the suprascapular nerve (SSN) at the spinoglenoid notch (SGN) specifically affects the infraspinatus, and isolated external rotation (ER) weakness can result. We describe the technique of open SSN decompression at the SGN for infraspinatus involvement and report the results of a consecutive series.

Materials And Methods: Twenty-nine shoulders underwent SSN decompression at the SGN. The mean age was 44 years (range, 15-69 years), and the mean follow-up was 4.3 years (range, 1-7 years). On manual muscle testing, ER strength was abnormal in all patients: 2/5 in 3, 3/5 in 21, and 4/5 in 5. The mean preoperative American Shoulder and Elbow Surgeons (ASES) score was 48 (range, 23-83). Atrophy of the infraspinatus was visible or palpable in 72% of shoulders. Magnetic resonance imaging showed ganglion cysts at the SGN in only 20.7% of shoulders.

Results: Of the patients, 19 (66%) regained full ER strength, 9 (31%) improved to 4/5, and 1 (3%) had ER strength of 3/5. The mean ASES score improved to 75 (range, 60-100) (P < .05). Of 29 shoulders, 23 (79%) showed improved ER strength within 1 week of surgery. All ganglion cyst cases regained full ER strength within a mean of 6 weeks. In all cases, ER strength improved by at least 1 full strength grade.

Discussion: A ganglion cyst is not necessary to produce SSN compression at the SGN. SSN compression at the SGN can present as an isolated entity or can occur in conjunction with rotator cuff pathology or a ganglion cyst. An index of suspicion, physical examination, magnetic resonance imaging, and electromyography confirm the diagnosis. The described operative approach detaches no muscle and allows rapid recovery, and in all cases, ER strength improved to normal or by 1 full grade.