What's thoracic output syndrome?

Brachial plexus : Tos is caused by compression of usually the lower brachial plexus at the level of the medial cord. A congenital cervical rib may be present but trauma can also cause the problem. Pain and numbness especially on elevation of the arm is characteristic, but the subclavian artery or vein may be involved. Thus, both neurogenic and vascular problems separate or together.