The subclavian artery and brachial plexus emerge through a narrow space between the clavicle and the first rib to enter the axilla. Compression of either the artery, or the eighth cervical and/or first thoracic nerve in this space produces a clinical picture referred to as the thoracic outlet syndrome. This is a misnomer as the pathology lies around the anatomical thoracic inlet. Many deformities and lesions are responsible.
Further investigation aims to exclude other causes of similar symptoms such as a cervical disc pathology or an atypical presentation of the carpal tunnel syndrome.
The syndrome is more common in women.