Supraspinatus Unusual Atrophy Pattern: A Case Report

We present the case of an unusual atrophy pattern of the supraspinatus muscle subsequent to suprascapular nerve compression by a paralabral cyst located in the spinoglenoid notch. A 58-year-old right-handed manual female worker presented to a specialized shoulder consultation with severe progressive pain in her right shoulder. Clinical exam revealed isolated limitation in active abduction and a painful Jobe test. MR-arthrogram showed a 12 × 10 mm paralabral cyst consecutive to a superior labral anterior to posterior (SLAP) II lesion, associated with an isolated supraspinatus Thomazeau stage II atrophy and Goutallier stage II fatty infiltration. A rotator cuff tear was excluded. After a failed nonoperative management, the patient underwent arthroscopic cyst decompression, SLAP debridement and biceps tenodesis, and presented satisfactory pain relief at 12 months follow-up with a constant score of 76 points. A control MR-arthrogram showed no recurrence of the cyst with regression of atrophy to stage I. In addition to confirm the known association between SLAP lesions and paralabral cysts, and to support the debated reversibility of atrophy, this presented case reveals the existence of a new type of lesion induced by suprascapular nerve compression, consisting in isolated denervation of the supraspinatus muscle. This can be explained by an anatomic variation of the supraspinatus branch of the nerve which had an unusually distal origin, whereas typical compression patterns involve either supraspinatus and infraspinatus, or infraspinatus alone.