Pectoralis Minor Syndrome

Pectoralis minor syndrome (PMS) is a subset of neurogenic thoracic outlet syndrome (TOS) that can cause upper extremity symptoms of pain, paresthesia, and/or weakness due to compression of the neurovascular bundle by the pectoralis minor muscle (PM). The most distinguishing symptoms and signs of PMS include pain and/or tenderness in the subclavicular anterior chest wall and axilla. The clinical diagnosis of PMS can be confirmed by an improvement in symptoms and physical findings following a PM muscle block with local anesthetic. Treatment begins with PM stretching exercises. If this is insufficient, PM tenotomy (PMT) is a low risk operation, which can be performed as an outpatient. When PMS is the only diagnosis the success rate of PMT is 90 %, but when PMS is accompanied by nerve compression at the level of the scalene triangle the success rate of isolated PMT is only 35 %. PMS should also be considered in all patients with recurrent neurogenic TOS, as this condition has been found in a substantial proportion of such patients.