Thoracic Outlet Syndrome

What is Thoracic Outlet Syndrome?

The thoracic outlet is an anatomical space between the clavicle and the first rib in the lower neck, which allows several important neurovascular structures to pass. The structures include the brachial plexus, subclavian artery, and subclavian brain. Compression of these vessels causes multiple problems such as upper extremity pallor, paraesthesia, weakness, muscle atrophy and pain. Therefore, thoracic outlet syndrome may be defined as a group of diverse disorders that result in compression of the neurovascular bundle exiting the thoracic outlet.


What causes Thoracic Outlet Syndrome?

The pathophysiology of symptoms causing thoracic outlet syndrome can be categorised into neurogenic, venous, and arterial aetiologies. Additionally, they can be further categorised into congenital, traumatic, or functionally acquired causes. The causes of TOS vary, and can include abrupt movements, hypertrophy of the neck musculature, and anatomical variations in which the brachial plexus roots pass-through this musculature, oedema, pregnancy, repeated overhead movements, blocked blood vessels, or abnormal posture.


Examples of:

          Congenital: the presence of a cervical rib or an anomalous first rib

          Traumatic: most commonly include whip-lash injuries and falls

          Functional acquired causes: related to vigorous, repetitive activity associated with sports or work


Examination of thoracic outlet syndrome

TOS subtype



Arterial TOS

Claudication/rest pain of upper limb, excluding shoulder/neck

Numbness, coolness, pallor

Raynaud’s phenomenon

Upper limb ischaemia, digital ulceration, peripheral embolisation

Pulsatile mass ± bruit on auscultation

Blood pressure differential >20 mmHg

Positive EAST, ULTT, Adson’s test

Venous TOS

Pain with movement or at rest in upper limbs, shoulders, and chest

Swelling and cyanotic discolouration

Upper limb swelling


Positive EAST, ULTT, Adson’s test


Neurogenic TOS

Having pain in neck, trapezius, shoulder, arm, and chest, as well as headaches in the occiput

Variable pattern upper limb weakness, numbness, paraesthesias

Tenderness on palpation: scalene triangle, subcoracoid space

Upper plexus (C5-C7): sensory disturbance of arm. Weakness/atrophy of deltoid, biceps, brachialis

Lower plexus (C8-T1): sensory disturbances in the forearm and hand. Inability to flex the wrist & fingers due to weakness & atrophy of small muscles in the hand

Positive EAST, ULTT, Adson’s test

Diagnostic tests for thoracic outlet syndrome



Positive test

Adson maneuver

The affected arm is fully extended at the shoulder and abducted 30°. The patient stretches his or her neck and inhales deeply as he or she turns the head toward the symptomatic shoulder


Decrease or absence of ipsilateral radial pulse


Wright maneuver

The shoulder on the symptomatic side is abducted above 90° and externally rotated


Decrease or absence of ipsilateral radial pulse


Halsted maneuver

Abduct, extend to 45°, and rotate the affected arm externally. A downward traction is applied to the arm, and the patient’s neck is turned away from the affected side


Decrease or absence of ipsilateral radial pulse


EAST (Roos test)

With the arms in the surrender position, the shoulders are abducted 90 degrees and in external rotation and the elbows flexed to 90°. During this exercise, he opens and closes the hands for 3 min


Provoking pain, paresthesia, heaviness, or weakness



The following positions are possible: Position 1: Arms elongated at 90° with elbows flexed; Position 2: Active dorsiflexion of both wrists; Position 3: Head is tilted ear to shoulder in both directions


Symptoms are triggered on the ipsilateral side by positions 1 and 2, while the contralateral side is elicited by position 3.



Differential diagnoses for thoracic outlet syndrome and their distinguishing clinical features

          Raynaud’s syndrome: cold fingers, colour changes in the skin in response to cold or stress that are relieved by warmth

          Vasculitis: severe sudden-onset pain involving more than one limb, elevated C-reactive protein level, skin lesions

          Rotator cuff tear: pain during shoulder movement that is easily differentiated by ultrasound

          Cervical radiculopathy: acute pain (disc rupture), insidious onset (spinal stenosis), spurling sign (+), denervating potential of cervical paraspinalis on electromyography

          Cubital tunnel syndrome: Tinel sign (+) over cubital tunnel: differentiated by nerve conduction study

          Guyon’s canal syndrome: Tinel sign (+) over Guyon’s canal: differentiated by nerve conduction study

          Neuralgic amyotrophy: extreme sudden-onset pain followed by rapid motor weakness and atrophy

          Pancoast tumour: pain in the shoulder radiating to the inner part of the scapula, possible Horner syndrome, tumor on the apex of the lung

          Complex regional pain syndrome: diffuse pain, predominant vasomotor features, history of stroke, trauma, or peripheral nerve injury


Treatment/management of Thoracic Outlet Syndrome

Patients with TOS symptoms are relieved by conservative treatment and therapeutic strategies depending on the type of TOS the individual has. However, consensus on appropriate conservative therapeutic treatment methods is lacking. In rehabilitation therapy, the initial treatment strategies implemented are patient education on postural mechanics, relaxation techniques and weight control, exercise including stretching and strengthening of targeted muscles, and activity modification. For neuropathic pain, oral pain medications are often used. Thrombolysis with continuous infusion of a plasminogen activator is commonly used to treat venous TOS. The most effective treatment for arterial TOS is thrombolysis or embolectomy. The gold standard of treatment remains surgery to maximize function or preserve limb, and it is vital that future research clarifies the ideal pain and physiotherapy regimens, as well as novel approaches to neurovascular decompression.


Despite the different types of TOS, exercise has been shown to be a useful approach in 50-90% of all TOS cases. Symptoms of TOS generally improve with exercise and other physical therapy techniques. When treating TOS, a general exercise session might emphasize proper scapular function, breathing techniques, and head and pelvic alignment during various activities. The aim of resistance exercises is to achieve muscular endurance with low weight and a high number of repetitions. It is important to understand that strength training alone won’t alter the pathophysiology of TOS, but requires a combination of strengthening, stretching and postural adjustments.


A basic exercise program may include:

          Scapular retraction and depressions

          Standing shoulder external rotations

          Banded straight arm extension

          Prone shoulder extension/abduction/horizontal abduction

          Frontal and lateral raise

          Serratus push with DB

          Chin tucks



Chang, M. C., & Kim, D. H. (2021). Essentials of thoracic outlet syndrome: A narrative review. World Journal of Clinical Cases, 9(21), 5804. https://doi.org/10.12998/wjcc.v9.i21.5804


Jones, M. R., Prabhakar, A., Viswanath, O., Urits, I., Green, J. B., Kendrick, J. B., … & Kaye, A. D. (2019). Thoracic outlet syndrome: a comprehensive review of pathophysiology, diagnosis, and treatment. Pain and therapy, 8(1), 5-18. https://doi.org/10.1007/s40122-019-0124-2


Levine, N. A., & Rigby, B. R. (2018, June). Thoracic outlet syndrome: biomechanical and exercise considerations. In Healthcare (Vol. 6, No. 2, p. 68). Multidisciplinary Digital Publishing Institute. https://doi.org/10.3390/healthcare6020068


Ohman, J. W., & Thompson, R. W. (2020). Thoracic outlet syndrome in the overhead athlete: diagnosis and treatment recommendations. Current Reviews in Musculoskeletal Medicine, 13, 457-471. https://doi.org/10.1007/s12178-020-09643-x


Povlsen, S., & Povlsen, B. (2018). Diagnosing thoracic outlet syndrome: current approaches and future directions. Diagnostics, 8(1), 21. https://doi.org/10.3390/diagnostics8010021




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