Disclosures: Nicholas Spinuzza, MD: Nothing to disclose

Case Description: 45F w/ external rotation (ER) weakness without paresthesias following a left shoulder arthroscopic debridement and subacromial decompressive acromioplasty 4 years prior at an outside hospital. Patient experienced pain relief following procedure, however, persistent weakness despite physical therapy. Electromyography of supraspinatus and infraspinatus muscles 2 years prior did not demonstrate abnormalities despite marked infraspinatus atrophy on MRI.

Setting: Electrodiagnostic Clinic

Patient: 45F

Assessment/Results: At presentation, 4/5 left shoulder ER in the setting of subtle palpable infraspinatus atrophy and without paresthesia/numbness. Electromyography was challenging due to a fibrous band at trapezius’ deepest aspect just superficial to a thin tissue overlying the scapula demonstrating decreased insertional activity with distant motor unit action potentials (MUAP) on ER. As this didn’t fit the clinical picture, needle was left in place while nearby musculature was activated differentiating between normal infraspinatous vs pathology more congruent with physical exam/imaging. Activation of trapezius (via scapula adduction) and posterior deltoid (via shoulder extension while at 90⁰ abduction). Increased activity was seen, confirming the distant MUAPs were red herring and infraspinatus had no voluntary MUAPs. Given that the supraspinatus, deltoid, and biceps were normal, we diagnosed patient with axonal neuropathy of right suprascapular nerve prior to innervating infraspinatus.

Discussion: Arthroscopic debridement and subacromial decompressive acromioplasty is well tolerated, however, due to the proximity of suprascapular and spinoglenoid notches, nerve injury can result due to either direct iatrogenic trauma or aberrant tissue healing. Furthermore, this case illustrates the importance of utilizing electrodiagnostic studies as an extension of clinical history/physical, as misdiagnosis is readily possible without appropriate troubleshooting when findings do not correlate. A thorough anatomic understanding can help prevent both iatrogenic injury and aid post-operative diagnosis.

Conclusion: Suprascapular nerve injury is an uncommon complication of arthroscopic debridement and subacromial decompressive acromioplasty. Physicians should have familiarity with anatomy to guide appropriate clinical suspicion for nerve injuries in post-operative patients presenting with deficits.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/suprascapular-neuropathy-following-arthroscopic-shoulder-debridement-and-subacromial-decompressive-acromioplasty-an-uncommon-surgical-complication/