All should be familiar with the presenting signs and symptoms of TOS, and include the syndrome in their differential diagnosis. TOS typically presents with aching-type pain radiating from the scapula down the upper extremity, with associated numbness or tingling. It is common in women between 20 and 50 years of age TOS is usually divided into three groups: vascular TOS, in those with compression of the subclavian vessels; neurogenic TOS, those with compression of the brachial plexus; and disputed neurogenic TOS (Roos, 1984). The diagnosis of TOS can be made by history, clinical examination, provocative tests, ultrasound, vascular studies, radiological evaluation, and electrodiagnostic evaluation. Initially, conservative treatment is offered to most patients. Definitive treatment involves surgical decompression of the related structures (Roos, 1984)
TOS subcategories usually are caused by the compression of brachial plexus elements and/or vasculature, which occurs in what is called thoracic outlet (TO), but really is the thoracic "inlet." The compressive sites within this anatomic territory vary and include the interscalene triangle, the most common location, and the costoclavicular and subcoracoid spaces. The TO, more correctly termed thoracic inlet, is a pyramidal space bordered anteriorly by (1) the claviculomanubrial complex, laterally by (2) the first rib and posteriorly by (3) the vertebral column (Roos, 1984). Contained in this space are the apex of the lung and pleura, the subclavian artery and veins and jugular vein, the lymphatics, the anterior and middle scalene muscles, the brachial plexus trunks and the sympathetic trunk. The thoracic inlet region can be subdivided into 3 anatomic spaces, each of which can be the site of compression of the structures therein. The spaces and their associated compression syndromes include: the proximal (1) interscalene triangle, associated with the "scalenus anticus syndrome," a TOS without a bony abnormality and due to compression of the brachial plexus and/or vasculature between hypertrophied anterior and middle scalene muscles. There is also, next, the (2) costoclavicular triangle or space, resulting in the costoclavicular syndrome, owing to narrowing of the space between the clavicle and first rib, and the (3) subcoracoid space. The subclavian vessels and brachial plexus traverse these 3 anatomic spaces within the cervico-axillary canal before reaching the arm (Divi etal, 2005).
These can be arterial or venous. Arterial TOS results from subclavian artery compression and insufficiency, which manifests as intermittent arm and/or hand coolness and fatigue. Actual arterial damage can occur and result in an aneurysm, embolus, and/or vessel occlusion with accompanying advanced ischemia, or even gangrene. Venous TOS is another form of vascular TOS presenting as intermittent mild arm swelling and duskiness from subclavian vein compression owing to bony anomalies or fascial bands at the level of the thoracic inlet (Divi etal, 200). These mild findings can progress to constant pain and severe upper extremity edema with skin discoloration. A pulmonary embolus from subclavian vein injury and thrombosis may ultimately occur (Roos, 1984)
Investigation for vascular TOS
In the radiologic evaluation of a patient with possible TOS, chest x-rays may reveal