Neuralgic Amyotrophy Following B‐Cell Maturation Antigen‐Directed CAR ‐T Therapy

Introduction/Aims Chimeric antigen receptor T‐cell (CAR‐T) therapy has transformed the management of refractory hematologic malignancies, but neurologic complications remain a major concern. While immune effector cell‐associated neurotoxicity syndrome is well recognized, peripheral neuropathies such as neuralgic amyotrophy have rarely been described. Methods We characterize the clinical, electrophysiologic, and imaging features of neuralgic amyotrophy after B‐cell maturation antigen (BCMA)‐directed CAR‐T therapy at a single tertiary care center. Results We identified four patients with neuralgic amyotrophy following BCMA‐directed CAR‐T therapy, corresponding to 1.5% of total patients treated in that time. Patients developed acute bilateral shoulder pain followed by weakness 8–12 days after CAR‐T infusion. Manifestations included scapular winging and arm weakness, with electromyography showing denervation most prominently in the muscles supplied by the long thoracic and suprascapular nerves. Corticosteroid use appeared to be associated with symptomatic improvement, although residual weakness persisted in most. Diagnosis was delayed in three patients due to misattribution of symptoms to other causes. Discussion Neuralgic amyotrophy may represent an underrecognized complication of BCMA‐directed CAR‐T therapy. The consistent timing of onset, bilateral involvement, and responsiveness to corticosteroids support an inflammatory mechanism. Clinicians should maintain vigilance for this complication, as prompt recognition and treatment may mitigate long‐term neurological morbidity.