813 - Botulinum Toxin Injection as a Treatment for Pectoralis Minor Syndrome in a Patient with Radiation Fibrosis Syndrome

Case Diagnosis: Pectoralis minor syndrome in the setting of radiation fibrosis syndrome

Case Description: 30-year-old female with history of left breast cancer status post bilateral mastectomy, reconstruction, and radiation therapy to the left breast presented with left chest wall pain and intermittent numbness and paresthesia in the left 4th and 5th digits. Symptoms were exacerbated by raising the arm above 90 degrees. Physical exam showed left pectoralis hypertonicity and reproduction of paresthesias in shoulder abduction. Notable negative findings included Tinel’s sign at the ulnar nerve and Spurling's. Electromyography study showed increased insertional activity in left abductor digiti minimi and abductor pollicis brevis. Presentation suggestive of pectoralis minor syndrome. Initial physical therapy with minimal benefit. Botulinum toxin injection of 75 units into the left pectoralis resulted in 70% improvement in symptoms which waned after 3 months. Subsequently 100 units were injected into left pectoralis which resulted in further improvement in symptoms with only rare and significantly less severe paresthesia.

Discussions:

Pectoralis minor length is commonly decreased following breast cancer treatment and may be further impacted by progressive fibrosis and sclerosis as late effects of radiation therapy. This case highlights a breast cancer survivor with pectoralis minor syndrome who responded well to treatment with botulinum toxin injections. She had improved numbness and paresthesia in her hand, and she was better able to perform essential work specific tasks. Current treatment recommendations for pectoralis minor syndrome may include physical therapy for stretching and, for refractory cases, tenotomy surgery. Botulinum toxin injections into the pectoralis muscles have been an effective non-operative, minimally invasive treatment option for this patient with pectoralis minor syndrome.

Conclusions:

Botulinum toxin injections may be utilized as an effective treatment method for pectoralis minor syndrome for breast cancer survivors.