![]() Thoracic-Outlet-Syndrome-Table-1 Download Classic syndromes have been defined as follows: Compression mainly occurs in these three sites 27 The Scalene Triangle Space, Costoclavicular Space, and Pectoralis minor Space (Also known as Subcoracoid Space) is represented with dotted circles in image to the left. Nonspecific thoracic outlet syndrome may be seen secondary to kyphotic posture, tight pectoralis muscles and latissimus dorsi. Repetitive shoulder use and above-shoulder athletic endeavors (swimming, throwing) may increase injury risk 6, 27-29. ![]() 1 Functional thoracic outlet syndrome has been associated in case reports with postural deviation, including increased kyphosis exacerbating compression at the thoracic inlet. 2 Repetitive trauma to the neurovascular bundle at the thoracic inlet may lead to TOS, with the lower trunk or medial cord of the brachial plexus most affected. 4 Anomalous bands may arise from cervical or rudimentary first thoracic rib, C7 vertebra, subpleural membrane, or scalene muscles. 2,7,8 Cervical ribs are a rarity most are asymptomatic. 2 Fibrous bands are more likely than rib anomalies to cause constrictions. 2 Interscalene triangle surface area can be decreased by cervical ribs, fibrous bands, and kyphotic musculoskeletal anatomy. Compression most often occurs at the interscalene triangle. 2, 27-29 The neurovascular bundle can be compressed or irritated at any of these structures. 1, 27-33 The thoracic inlet can be divided into three sections: the interscalene triangle, the costoclavicular triangle, and the subcoracoid/pectoralis minor space. TOS occurs secondary to compression of the subclavian artery, subclavian vein, or brachial plexus at the level of the thoracic inlet. ![]() 5 The typical age range for the development of vTOS is between 20 to 30 years of age. 28 Both vTOS and aTOS usually develop in young patients without significant comorbidities. Studies indicate average range of development of nTOS is between teenage to 60 years of age. ![]() 5, 29 Studies indicate that vTOS affects a similar proportion of men and women. 4 The female/male ratio for nTOS is 3.5:1 and there is no sex predilection for aTOS or vTOS. Venous TOS (vTOS) accounts for 3% and arterial TOS (aTOS) is estimated to have the lowest incidence, at less than 1%. 2 Proportionately, neurogenic TOS (nTOS) is estimated to comprise over 90% of TOS. Some authors propose an incidence of 3-80 cases per 1000. 28, 29, 33 Epidemiology including risk factors and primary preventionĪccurate diagnosis and incidence of TOS is difficult due to the absence of consistently reproducible objective measures. 1,28,29 Compression may occur from soft tissue mass or abnormal musculoligamentous and bony structures these changes may be congenital, or they may be related to trauma, overuse, or neoplasm. TOS may result from compression or irritation of the brachial plexus, subclavian vein, subclavian artery, or a combination of the three. Based on the principal site of compression or irritation, the disorder is classified as either true (classic) neurogenic TOS, vascular TOS, or nonspecific TOS. Thoracic outlet syndrome (TOS) refers to a constellation of upper extremity symptoms from compression of neurovascular structures coursing through the thoracic inlet.
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