Thoracic Outlet Syndrome (TOS)
Thoracic outlet syndrome (TOS) is a group of symptoms caused by compression of the brachial plexus, subclavian artery or subclavian vein in the narrow anatomical passage of the neck-shoulder region. The neurogenic type (nerve compression) is the most common; the arterial and venous types are rare. Treatment is usually conservative (physiotherapy, postural correction); in refractory or vascular cases, surgery (first rib resection, scalenectomy) is performed.
最后更新: 2026-06-07
Definition and Anatomy
The thoracic outlet is the narrow anatomical region where the brachial plexus and subclavian vessels pass from the chest to the arm. There are three main areas of narrowing: the interscalene triangle (between the anterior and middle scalene muscles and the first rib), the costoclavicular space (between the clavicle and the first rib) and the subcoracoid space (beneath the pectoralis minor muscle). Compression of the neurovascular structures in these areas leads to TOS. Depending on the structure involved, neurogenic (most common), arterial and venous subtypes are defined.
Causes and Risk Factors
The main causes include anatomical variations (cervical rib, long C7 transverse process, fibrous bands), trauma (clavicle fracture and callus, whiplash), postural abnormalities (forward shoulder posture, desk-based posture), repetitive overhead activities (swimming, volleyball, painting) and muscle hypertrophy/spasm (scalene muscles, pectoralis minor). Obesity and pregnancy may also contribute. A cervical rib is uncommon in the population and is asymptomatic in most people; however, when present it may compress the lower roots of the brachial plexus (C8-T1).
Symptoms
Neurogenic TOS is the most common type; it causes numbness and tingling in the arm and hand (particularly the fourth and fifth fingers and the medial border of the hand), neck-shoulder-arm pain, hand weakness and, in long-standing cases, atrophy of the intrinsic hand muscles. Symptoms are position-dependent (arm raised, overhead activities) and may worsen at night. In arterial TOS there may be limb ischaemia, coldness, pallor and colour change in the fingers due to embolism (ischaemia). Venous TOS (Paget-Schroetter syndrome) presents with sudden arm swelling, pain, bluish discolouration (cyanosis) and prominence of superficial veins; it usually occurs after intense activity in young, active individuals.
Diagnosis
TOS is a clinical diagnosis; there is no single definitive laboratory test. In addition to history and physical examination, provocation tests (Adson, Wright, Roos/EAST) help reproduce the symptoms and demonstrate pulse changes; because these tests can be misleading on their own, reproduction of the patient's symptoms is important. A cervical radiograph is assessed for a cervical rib. MRI demonstrates soft-tissue pathology. EMG/nerve conduction studies may be normal in neurogenic TOS but are valuable in distinguishing other conditions such as carpal tunnel syndrome, ulnar entrapment neuropathy and cervical radiculopathy. In the vascular types, angiography or venography (with Doppler ultrasound when needed) is used.
Conservative Treatment
Particularly in neurogenic TOS, conservative management is the mainstay and is usually applied for 3-6 months. Physiotherapy is central: postural correction (correcting forward shoulder posture, chin retraction, ergonomic adjustments), stretching exercises for the scalene and pectoralis minor muscles, and strengthening of the periscapular muscles (middle and lower trapezius, serratus anterior). Neuropathic pain agents, muscle relaxants and short courses of anti-inflammatories are used for symptomatic treatment. A scalene muscle block may be used for both diagnostic and therapeutic purposes. Activity modification (avoiding overhead activities, limiting heavy lifting) is important.
Surgical Treatment
Surgery is considered in neurogenic TOS that does not respond to 3-6 months of conservative treatment, has progressive neurological deficit or function-limiting pain, or in which a marked anatomical anomaly (cervical rib) is identified. Arterial TOS (acute ischaemia, aneurysm, recurrent embolism) and venous TOS more often require interventional/surgical treatment. The main operation is first rib resection (by a transaxillary, supraclavicular or infraclavicular approach), which relieves compression by widening the thoracic outlet. Scalenectomy and cervical rib excision may be performed together or alone. In arterial TOS, vascular reconstruction is performed when needed; in venous TOS (Paget-Schroetter), thrombolytic therapy is followed by decompression. Possible complications include brachial plexus injury, pneumothorax and recurrence.
Prognosis
A significant proportion of neurogenic TOS cases respond well to conservative treatment; outcomes are favourable, particularly in postural and mild cases. In cases requiring surgery, good/excellent results are reported in most, although recurrence is possible. In arterial and venous TOS, early diagnosis and appropriate intervention determine the prognosis. Long-standing symptoms and the development of muscle atrophy adversely affect the prognosis. The treatment plan is individualised for each patient, and no outcome can be guaranteed in advance.
参考文献
- Winn HR, ed. Youmans Neurological Surgery. 6th ed. Saunders; 2011:2441-2447.
- Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg. 2007;46(3):601-604.
- Illig KA, Donahue D, Duncan A, et al. Reporting standards of the Society for Vascular Surgery for thoracic outlet syndrome. J Vasc Surg. 2016;64(3):e23-e35.
- Povlsen B, Hansson T, Povlsen SD. Treatment for thoracic outlet syndrome. Cochrane Database Syst Rev. 2014;(11):CD007218.
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