Recurrent Neurogenic Thoracic Outlet Syndrome Stressing the Importance of Pectoralis Minor Syndrome

Background: Although first described over 60 years ago, neurogenic pectoralis minor syndrome (NPMS) has only recently been noted to be present in over half the patients with a clinical diagnosis of neurogenic thoracic outlet syndrome (NTOS). Similarly, NPMS has also been observed in the majority of patients with recurrent NTOS. This study explores the role of pectoralis minor tenotomy (PMT) in patients with recurrent NTOS. Methods: A total of 86 patients with symptoms of recurrent NTOS, who had failed to improve on conservative management, were evaluated by history and physical examination for both NPMS and NTOS. Diagnostic tests included pectoralis minor muscle (PMM) blocks, scalene muscle blocks, and medial antebrachial cutaneous nerve (MAC) measurements. Surgery was either PMT alone or PMT plus brachial plexus decompression (BPD). Follow-up was 1 to 3 years. Results: All patients had multiple symptoms of pain, weakness, and paresthesia. Patients who qualified for PMT alone had slightly fewer symptoms than those who required PMT plus BPD. There was essentially no difference in physical findings between the 2 groups. It was the response to PMM blocks and scalene muscle blocks that determined which of the 2 operations was performed. Pectoralis minor tenotomy alone gave 69% good results in 65 operations, with 8% fair and 23% failures. Pectoralis minor tenotomy plus BPD in 39 operations gave 58% good improvement, 20% fair and 22% failures. Conclusion: All patients with recurrent NTOS should be evaluated clinically for NPMS. If patients complain of pain or tenderness in the anterior chest wall and axilla, a diagnostic PMM block should be performed. A good response to the block suggests that consideration be given to performing PMT alone as it a simple, low-risk outpatient procedure. If unsuccessful, BPD can be performed at a later date. If there is a poor response to the PMM block, BPD is indicated along with PMT, provided there were some symptoms of NPMS.