Thoracic outlet syndrome

Abstract

Thoracic outlet syndrome (TOS) consists of a group of three syndromes resulting from compression of the subclavian artery (arterial – ATOS), brachial plexus (neurogenic – NTOS) or subclavian vein (venous – VTOS) as they pass through the thoracic outlet. The thoracic outlet is not one, but three distinct anatomical spaces and compression at differing sites results in differing combinations of symptoms. NTOS is the most common, usually caused by compression of the brachial plexus in the scalene triangle or pectoralis minor space. In making the diagnosis of NTOS, neurogenic compression in the cervical spine, carpal and cubital tunnels should be excluded. Management of NTOS is usually conservative, with physiotherapy and postural exercise, but pain or muscle wasting may be indications for surgery. VTOS is caused by compression of the subclavian vein at the costoclavicular junction. It may present as acute venous thrombosis (Paget–Schroetter syndrome) or positional swelling of the upper limb without thrombosis (McCleery's syndrome). In acute thrombosis, clot lysis, rib excision and venoplasty may be indicated. ATOS occurs due to compression of the subclavian artery, often in association with an anomalous structure, such as a cervical rib. Post-stenotic aneurysmal dilatation of the artery can result in thrombosis and distal embolization. Acute upper limb ischaemia necessitates urgent rib excision and arterial reconstruction.