Thoracic outlet syndrome

Thoracic outlet syndrome (TOS) may affect neurologic or vascular structures, or both, depending on the component of the neurovascular bundle predominantly compressed.

Types include neurologic, arterial, venous, and neurovascular/combined, and patients may present with signs and symptoms of nerve, vein, or artery compression or any combination of these. Neurologic is the most common, while arterial, which is relatively rare, is arguably the most important to recognize owing to the risk of ischemia.

Neurologic TOS primarily develops spontaneously in people in their late teens up to the age of 60 years, and is more common in women. It usually occurs in the setting of congenital abnormalities of the thoracic outlet, hyperextension injuries, repetitive stress injuries (e.g., work related), and external compressing factors (e.g., poor posture).

Patients with venous or arterial occlusion require prompt evaluation for surgical intervention with thrombolysis and thoracic outlet decompression.

For most cases of disputed neurologic thoracic outlet syndrome, initial management is conservative and includes physical therapy. Surgical management of nerve compression is indicated in individuals who show physical signs of nerve damage or who have failed conservative treatments.

Thoracic outlet syndrome (TOS) refers to the compression of one or more of the neurovascular structures traversing the superior aperture of the chest.[1]Urschel HC Jr, Razzuk MA. Neurovascular compression in the thoracic outlet: changing management over 50 years. Ann Surg. 1998 Oct;228(4):609-17. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1191545/pdf/annsurg00008-0185.pdf http://www.ncbi.nlm.nih.gov/pubmed/9790350?tool=bestpractice.com The thoracic outlet is the area between the neck and shoulder, over the top of the thorax, and under the clavicle to the axilla.

Knowledge of the thoracic outlet anatomy is fundamental to the diagnosis of any type of TOS.[2]Peet RM, Hendriksen JD, Anderson TP, et al. Thoracic outlet syndrome: evaluation of the therapeutic exercise program. Proc Staff Meet Mayo Clin. 1956 May 2;31(9):281-7. http://www.ncbi.nlm.nih.gov/pubmed/13323047?tool=bestpractice.com [3]Urschel HC Jr. Anatomy of the thoracic outlet. In: Ferguson MK, Deslauriers J, eds. Thoracic surgery clinics, vol 17, no 4. Philadelphia, PA: Elsevier; 2007:511-520. The subclavian artery leaves the thorax by arching over the first rib behind the scalenus anticus muscle (anterior scalene) and in front of the scalenus medius muscle (middle scalene). It then passes under the clavicle and finally enters the axilla beneath the pectoralis minor muscle. The subclavian vein has an identical course, except that it passes anteriorly rather than posteriorly to the scalenus anticus muscle. The brachial plexus follows the route of the subclavian artery, but it lies a little more posteriorly and laterally. The axillary-subclavian vein traverses the tunnel formed by the clavicle and subclavius muscle anteriorly, the scalenus anticus muscle laterally, the first rib posterior-inferiorly, and the costoclavicular ligament medially.[4]Urschel HC Jr, Patel AN. Paget-Schroetter syndrome therapy: failure of intravenous stents. Ann Thorac Surg. 2003 Jun;75(6):1693-6. http://www.ncbi.nlm.nih.gov/pubmed/12822601?tool=bestpractice.com The anatomical areas within the thoracic outlet that can typically impart neurovascular compromise include the interscalene triangle, the costoclavicular space, and the subcoracoid space, although it is possible that the sternal-costovertebral bony circle may also be involved.[2]Peet RM, Hendriksen JD, Anderson TP, et al. Thoracic outlet syndrome: evaluation of the therapeutic exercise program. Proc Staff Meet Mayo Clin. 1956 May 2;31(9):281-7. http://www.ncbi.nlm.nih.gov/pubmed/13323047?tool=bestpractice.com [3]Urschel HC Jr. Anatomy of the thoracic outlet. In: Ferguson MK, Deslauriers J, eds. Thoracic surgery clinics, vol 17, no 4. Philadelphia, PA: Elsevier; 2007:511-520.[5]Wilbourn AJ. Thoracic outlet syndromes. Neurol Clin. 1999 Aug;17(3):477-97, vi. http://www.ncbi.nlm.nih.gov/pubmed/10393750?tool=bestpractice.com