thoracic outlet syndrome

The right brachial plexus with its short branches, viewed from in front. (Brachial plexus and subclavian artery are visible running in parallel near the center. Anterior scalene is visible in upper right.)Thoracic outlet syndrome(TOS) is a syndrome involving compression at the superior thorac. involving compression of a neurovascular bundle passing between the anterior scene.It can affect the brachial plexus (nerves that pass into the arms from the neck), and/or the subclavian artery or rarely thevein hich does not normally pass through the scalene hiatus (blood vessel  as they pass between the chest and upper extremity). Rarely a Pancoast tumour in the apex of the lung may be the cause.

The compression may be positional (caused by movement of the calive collarbone) and shoulder  arm movement) or static (caused by abnormalities or enlargement or spasm of the various muscles surrounding the arterye veins and brachial plexus), a first rib fixation and a cervical rib.

Common orthopaedic tests used are the Adson's test, the CostoClavicular manoeuvre and the Hands-Up test of East. Careful examination and X-ray are required to differentially diagnose between positional and static aetiology, first rib fixations, scalene muscle spasm and a cervical rib or fibrous band.