1008 - Thoracic Outlet Syndrome in a Breast Cancer Survivor: A Case Report

Case Diagnosis: Thoracic Outlet Syndrome

Case Description: 48-year-old female with left breast cancer history treated with bilateral mastectomy (left sentinel node biopsy, three nodes removed) without reconstruction, adjuvant chemotherapy (Taxotere, Cytoxan), and radiation to the left chest wall presented with four months of progressive bilateral arm pain, numbness, and nocturnal paresthesias, worse on the left. Symptoms radiated into the medial forearm and hands, worsened with overhead activity or shoulder depression. Exam showed bilateral paresthesias with provocative maneuvers (Adson’s, Roos), hyperreflexia, protracted shoulders, left axillary cording, and no cervical radicular signs. EMG revealed mild left ulnar motor slowing across the elbow and prolonged F-wave latency. Chest imaging was negative for cervical rib. Right arm MRA demonstrated mild subclavian vein narrowing with abduction. Although left arm MRA was unremarkable, it was positioned in significantly less abduction than her right arm without reproduction of symptoms. Management includes repeat left arm MRA with proper positioning, continuing physical therapy, and baclofen trial.

Discussions: Thoracic Outlet Syndrome (TOS) encompasses a group of disorders caused by compression of the neurovascular bundle traversing the thoracic outlet.
Radiation-induced fibrosis and post-mastectomy changes may predispose breast cancer patients to TOS by impacting the retropectoralis minor space, though the prevalence in breast cancer survivors remains poorly defined. This case serves as evidence that breast cancer rehabilitation patients may be predisposed to thoracic outlet pathology. Physical therapy will emphasize pectoralis minor stretching and myofascial release, and Botulinum toxin injection to pectoralis minor will be considered if symptoms persist.

Conclusions: TOS should be considered in patients with prior mastectomy or radiation presenting with upper extremity pain and neuropathic symptoms.