(Kiosk 3) Bilateral Neuralgic Amyotrophy Following Successive sars-cov-2 and Influenza Infections: A Case Report

Case Diagnosis: Bilateral Neuralgic Amyotrophy (NA)

Case Description or Program Description: 47 year-old male awoke with severe, throbbing left shoulder pain which persisted for two weeks. Pain was followed by severe left shoulder girdle weakness and paresthesias along both lateral forearms, right worse than left. He denied any cervical or radicular pain or any preceding injury or trauma.

Setting: Academic EMG Lab

Assessment/Results: He had unremarkable x-rays in the ED and was diagnosed with suspected rotator cuff tear. Upon further questioning, he reported severe SARS-CoV-2 infection two years prior followed by a milder reinfection four weeks before onset followed soon after by severe influenza infection.

Examination demonstrated 0/5 left shoulder abduction and 2/5 external rotation strength, scapular atrophy, and diminished sensation in lateral antebrachial cutaneous (LAC) distribution, right greater than left. He underwent electrodiagnostic testing 3 weeks later, having experienced significant clinical improvement.

Nerve conduction studies were equivocal for a mild right LAC neuropathy. EMG demonstrated fibrillation potentials and unstable, polyphasic motor unit action potentials in the left infraspinatus, supraspinatus, deltoid, and biceps.

Discussion (relevance): Given history and EMG findings, a diagnosis of bilateral NA was made. Over 50% of patients have an antecedent event with viral illness and vaccination most common. 10-30% may have a bilateral presentation which is usually asymmetric. While reports have associated a preceding SARS-CoV-2 infection or vaccination with NA, little is known regarding NA and reinfection or influenza co-infection. Additionally, reports have been limited to influenza vaccination.

Conclusions: NA is an uncommon neuromuscular syndrome affecting the brachial plexus. Diagnosis is clinical and largely of exclusion. We present a case involving bilateral LAC and left suprascapular, axillary, and musculocutaneous nerves following SARS-CoV-2 and influenza. As the incidence of NA with SARS-CoV-2 infection versus reinfection as well as successive or concurrent influenza infection remains unclear, further studies are needed to investigate these phenomena, including risk for atypical bilateral involvement.