Cale Melham, MD
Resident Physician
University of Toledo
Sylvania, Ohio, United States
Alexander Vogel, MD
Medical Student
University of Toledo
Waterville, Ohio, United States
Steven J. Farrell, MD
Professor and Division Chief, Residency Program Director
The University of Toledo College of Medicine
Toledo, Ohio, United States
Labral Cyst-Induced Suprascapular Nerve Compression and Ulnar Nerve Entrapment at the Wrist
Case Description:
A 50-year-old male presented with two months of left shoulder pain, weakness, and reduced active range of motion. Initial diagnosis was rotator cuff tendinitis. He was treated with a subacromial corticosteroid injection which provided temporary pain relief but did not improve weakness. He returned with persistent symptoms despite home exercises and anti-inflammatories. MRI revealed a labral tear with a large para-labral cyst compressing the suprascapular nerve, causing significant atrophy of the supraspinatus and infraspinatus. Left upper extremity electrodiagnostic testing revealed decreased motor amplitude and absent sensory response of the ulnar nerve at the wrist. There was increased insertional activity of the infraspinatus along with 2+ fibrillations and positive waves. There was increased duration and amplitude of volitional muscle unit action potentials, many polyphasic waves, and reduced recruitment in the supraspinatus, infraspinatus, and first dorsal interosseus, but not the flexor carpi ulnaris.
Discussions:
The electromyography changes in the supraspinatus and infraspinatus muscles were anticipated given the known suprascapular nerve compression. However, the detection of abnormalities in the ulnar nerve was unexpected, revealing an additional and unrelated neuropathy. Despite the absence of left-hand symptoms, the discovery of ulnar neuropathy highlights the benefit of electrodiagnostic studies in revealing underlying conditions that may not be clinically apparent but could significantly impact the patient's overall management and prognosis.
Conclusions: This case emphasizes the critical importance of thorough electrodiagnostic testing in identifying rare and concurrent neuropathic conditions. The simultaneous occurrence of a labral cyst causing suprascapular nerve compression and ulnar nerve entrapment at the wrist is an uncommon clinical scenario that may easily be overlooked without astute evaluation. Detailed electrodiagnostic studies are essential for uncovering complex, multi-site neuropathies, especially considering their role in guiding targeted therapeutic interventions.
