الفهرس 
AnatomyOnly 14 pages are availabe for public view
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Abstract
The thoracic outlet syndrome caused by compression of the neurovascular bundle at the thoracic outlet region.
The clinical presentation depending upon the three structures at risk (the subclavian artery, vein and the brachial plexus).
Three spaces that could be responsible for upper extremity neurovascular compression symptoms:
1- The interscalene triangle.
2- The costoclavicular space.
3- The subpectoral space.
The most common cause of compression is the cervical rib or just a fibrous band may cause compression. The incidence of cervical rib is 0.5 % to 0.6 % with 50 % to 80 % being bilateral. Female to male ratio is 2 : 1 .
A fracture first rib with excessive callus formation or exostosis of the first rib can narrow the space, causing pressure on the plexus and vessels. Fractures of the clavicle resulting in a malunion or nonunion with excessive callus may compress the neurovascular structures.
A single or repeated subacromial dislocation of the humeral head may be also a cause of compression. Other factors such as first rib anomalies, anatomical variations between subclavian artery, vein and scalenus muscle.
There is certain congenital anomalies, such as sprengel deformity, congenital elevation of the scapula, cervicodorsal scoliosis, and Khppei-Feil deformity, have also been known to cause compression or stretching of structures in the thoracic outlet.
Tumours play a role of compression of thoracic outlet such as a Schwannoma originating from T1 root may cause symptoms of compression.
Thoracic outlet syndrome generally divided into two specific types, neurogenic and vascular. About 10 % of all cases are pure or very dominant vascular type (venous or arterial). The remaining cases are neurogenic.
Venous TOS symptoms which are seen more often than arterial compression (8:2) consist of swelling and cyanosis of the extremity, with pain, heavy feeling, and venous distension in the upper arm and shoulder region.
Thrombosis of the subclavian vein frequently is caused by TOS and is called Paget-Schroetter syndrome.
True arterial TOS is rare. Symptoms usually are caused by the arterial insufficiency. They include extremity weakness and coldness and pain caused by ischaemic neuritis of the plexus, in severe cases of compression, subclavian artery thrombosis with peripheral embolization can be seen.
Neurogenic compression classified into three groups according to the level of the plexus involvement, upper, lower and combined. The upper involves C5 - C6 - C7 roots and the lower involves C8 - Tl roots. Symptoms of the lower and combined types comprise 85% to 90% of all TOS cases.
The most commonly seen symptoms in all types are pain and paraesthesia, weakness, with an easily fatigued extremity, and coolness, with cold intolerance. The pain usually is a dull aching feeling but sometimes can be sharp and throbbing and severe enough to require a narcotic agent for relief.
Neural compression can cause sympathetic over activity, producing vasomotor changes in the extremity like those observed in Raynaud,s disease. Horner,s syndrome on the affected side has been observed many times many patients gradually develop associated myofascitis.
Diagnosis is the most difficult component of the disease because there is associated frequent conditions particularly biceps or supraspinarus tendinitis of the shoulder. There are a significant number of patients who have combined TOS and carpal tunnel syndrome, in some cases there can even be a triple crush syndrome.
Lines of treatment can be divided in to
1) Preventive measures
- Essential to correct or eliminate any risk factors identified, particularly in the workplace. The use of orthoses has also provided useful results on distal symptoms in some patients.
2) Rehabilitation
Correctly conducted rehabilitation can provide prolonged relief of symptoms in about 2/3 of patients. It is especially effective on proximal pain.
3) Surgery
- some authors are in favour of supraclavicular scalenectomy, while others are in favour of transaxillary resection of the first rib.
- Scalenectomy appears to be associated with a lower success rate, and the results obtained also tend to wane with time. It can be responsible for certain vascular and neurological complications and appears to be associated with a higher incidence of postoperative reflex sympathetic dystrophy.