Electrodiagnostic / Neuromuscular Medicine
Christopher H. Yoo, MD
Resident Physician
University of California, Irvine
Orange, California, United States
Desmond James Barker, MD
Resident Physician
University of California, Irvine
Orange, California, United States
Gilbert Hernandez, DO
Resident Physician
University of California, Irvine
Orange, California, United States
Edward Chang, DO
Resident Physician
University of California, Irvine
Orange, California, United States
Bao Q. Tran, MD
Physician
University of California, Irvine
Orange, California, United States
Christopher H. Yoo, MD
Resident Physician
University of California, Irvine
Orange, California, United States
The utility of electrodiagnostic study to diagnose an unusual presentation of Parsonage-Turner Syndrome (PTS). PTS, or neuralgic amyotrophy, is a painful axonal process involving inflammation of the brachial plexus or peripheral nerves of the shoulder girdle, leading to acute pain followed by weakness. Seror et al. reported the nerves frequently affected include the long thoracic (39%), suprascapular (36%), anterior interosseous (15%), and spinal accessory (14%), with axillary nerve involvement at only 8%. This case is notable for the uncommon axillary distribution rather than the more typical long thoracic or anterior interosseous pattern. Because PTS is a diagnosis of exclusion, comprehensive history and physical examination are essential. In this patient, cervical MRI demonstrated multilevel neuroforaminal stenosis contralateral to the symptomatic side, and shoulder MRI suggested adhesive capsulitis. However, the clinical progression of acute neuropathic pain followed by delayed proximal weakness, combined with discordance between imaging and examination findings, raised suspicion for PTS. Ultimately, electrodiagnostic testing was critical to confirming the diagnosis and excluding alternative etiologies.
Case Description: A 75-year-old male with chronic neck pain developed two weeks of progressive right shoulder pain that acutely worsened after lifting. He presented to the emergency department with an inability to raise his arm. Exam showed weakness in shoulder abduction beyond 90 degrees and mild elbow flexion weakness, raising concern for C5 radiculopathy. Cervical MRI, however, revealed severe left-sided neuroforaminal stenosis but only mild changes on the symptomatic right side. Right shoulder MRI demonstrated edema in the rotator interval and axillary pouch, suggestive of adhesive capsulitis. Electrodiagnostic testing ultimately demonstrated acute denervation of the right deltoid and infraspinatus muscles with sparing of cervical paraspinals, consistent with Parsonage–Turner Syndrome.
Discussions:
Conclusions: Parsonage–Turner Syndrome may present with uncommon axillary nerve involvement, and electrodiagnostic testing is essential when imaging findings are discordant.
