Working Diagnosis:
Anatomic suprascapular nerve entrapment - stenotic notch with an aberrant transverse scapular ligament branch

Treatment:
Left shoulder arthroscopic capsulorrhaphy, posterior Bankart repair, extensive debridement, suprascapular nerve decompression

Outcome:
At the four-week postoperative follow-up visit, the athlete had no complications. She remained in the posterior immobilizer and had begun gentle active range-of-motion exercises. She reported improvement in pain from 8/10 preoperatively to 4/10, with complete resolution of numbness and tingling. Weakness persisted, although she had only recently initiated range-of-motion exercises. She planned to graduate the following month and did not intend to return to collegiate volleyball.

Author's Comments:
Suprascapular neuropathy is a recognized cause of shoulder pain and dysfunction in overhead athletes. While commonly associated with labral pathology, anatomical variations of the suprascapular notch can predispose to suprascapular nerve entrapment. This case highlights a stenotic notch with an aberrant transverse scapular ligament branch, resulting in nerve impingement and isolated infraspinatus atrophy typically seen with spinoglenoid-notch compression. Such subtle anatomical variants may be difficult to detect on imaging and can cause persistent functional deficits, emphasizing the importance of considering atypical structural etiologies in athletes with unexplained shoulder symptoms.

Editor's Comments:
Interesting case with several teaching points.
The incidence is high in repetitive overhead athletes, with incidence as high as 50% in tennis players and 33% in volleyball players.

The suprascapular nerve does not provide cutaneous sensation. Therefore the presentation can mimic rotator cuff pathology, specifically with weakness in ER as in this case.
Several keys to the diagnosis here, first of which was careful inspection of the posterior shoulder to observe isolated infraspinatus atrophy. The second was posterolateral pain with tenderness to palpation of the muscle belly and not the insertion. Finally, there was significant muscle atrophy without evidence of a RTC tear on MRI. This case is unique in that there was no compression by a paralabral cyst, which is the classic presentation.

Other etiologies include traction injury to the nerve from repetitive overhead activity, trauma to the scapula, or Parsonage-Turner syndrome. Parsonage-Turner syndrome, also called brachial neuritis, presents w/ severe pain in the shoulder, followed by weakness and muscle atrophy. This syndrome is associated with a recent illness, so her pneumonia 1 to 2 months prior to presentation could have been a trigger. If that was the ultimate diagnosis one would expect sensory findings. EMG also distinguishes this syndrome from isolated suprascapular neuropathy.

Evaluation can include radiographs with a Stryker notch view, MRI, ultrasound to visualize the nerve and compressive lesions, and EMG. The diagnostic/ therapeutic notch hydrodissection was a useful unique aspect of this case as well.

References:
1.Surya P, Pankhania R, Ul Islam S. Suprascapular Neuropathy in Overhead Athletes: A Systematic Review of Aetiology and Treatment Options . Open Orthop J, 2019; 13:. http://dx.doi.org/10.2174/1874325001913010177
2.Bagoji IB, Hadimani GA, Bulgoud RS, Desai V, Prakash KG, Bharatha A. Anatomical Variations of the Suprascapular Notch and its Importance in Suprascapular Entrapment Neuropathy. Maedica (Bucur). 2020 Sep;15(3):298-304. doi: 10.26574/maedica.2020.15.3.298. PMID: 33312243; PMCID: PMC7726504.

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