Thoracic Outlet Syndrome (Costoclavicular Syndrome)


Thoracic outlet syndrome (TOS) is not the name of a single entity, but rather a collective title that encompasses a variety of conditions produced by compression of nerves, arteries and or veins (or all) because of an inadequate passageway through an area (thoracic outlet) between the base of the neck and the armpit.    The thoracic outlet is bordered by the scalene muscles, first rib, and clavicle.

thoracic outlet



Thoracic outlet syndrome symptoms include neck, shoulder pain, arm pain, numbness and paraesthesiae (pins and needles) fingers and impaired circulation of the extremities (so there may be for example, discolouration of the hands.)   Symptoms can be constant or intermittent depending on what activities are being performed.    Any condition that results in enlargement or movement of these tissues of or near the thoracic outlet can cause the thoracic outlet syndrome.  Risk factors include trauma, occupations or sports that involve heavy usage of the upper extremities against resistance, including jack-hammer operators and dental hygienists, weight lifting, pregnancy, poor posture and obesity.  Pregnancy is thought to affect the thoracic outlet by the loosening of joints during pregnancy.  Rarely lung tumours can affect the outlet.


Thoracic outlet syndrome was first described in soldiers with loaded backpacks who developed pain, numbness and arm fatigueability as they stood at attention, and results published in 1943.(6)   “The mechanism of compression involved downward movement of the clavicle against the first rib, with a resultant tendency to shearing of the neurovascular bundle.” (5)   This same mechanism was thought to explain subclavian vein thrombosis precipitated by prolonged heavy exercise of the upper extremities- Paget-Schroetter Syndrome.    De Silva then described the same mechanism occurring in heavy breasted women with tight bra straps again shearing the neurovascular bundle.


Venous thoracic outlet compression has been associated with intractable migraine(1)  From ongoing research underway at present in the association between popliteal vein compression syndrome and migraine- this is most likely from cascades of inflammatory chemicals (and /or micremboli) that form when the blood is stagnant when the popliteal, axillary or subclavian veins are compressed.  There is some research that has associated TOS with autoimmune disease, and depression.   Thrombosis of the veins has been associated with pulmonary emboli, just as popliteal vein compression is a cause of DVT and pulmonary emboli.

Sport Specific Biomechanics

Thoracic outlet syndrome is most often seen in patients who engage in repetitive motions that place the shoulder at the extreme of abduction and external rotation. An example of such activity is swimming, especially with the freestyle, butterfly, and backstroke. When a swimmer reports tightness and pain around the shoulder, neck, and clavicle as his or her hand enters the water, thoracic outlet syndrome should be suspected.   Other athletes affected include water polo, baseball, and tennis players and athletes in any other activity that places repetitive stress on the shoulder at the extremes of abduction and external rotation.   It is also found in musicians, waiters and others working above their shoulders.


Illig and Doyle(4) write: “the subclavian vein is highly vulnerable to injury as it passes by the junction of the first rib and clavicle in the anterior-most part of the thoracic outlet.  In addition to extrinsic compression, repetitive forces in this area frequently lead to fixed intrinsic damage and extrinsic scar tissue formation.   Venous thoracic outlet syndrome progressing to the point of axillosubclavian vein thrombosis, variously referred to as Paget-Schroetter syndrome or effort thrombosis, is a classic example of an entity which if treated correctly has minimal long-term sequelae but if ignored is associated with significant long-term morbidity.”(25)



Surgery in cases of thoracic outlet syndrome is indicated for acute vascular insufficiency and progressive neurologic dysfunction.   Neurological symptoms may persist in patients following surgery to remove the first ribs, thus freeing the venous compression, but scarring of the nerves that envelop the vessels causes the prolonged symptoms after surgery, and which would mean that the observed vein compression seen in vascular scanning is only a guide to the presence of the compression producing the sensitization.

Physiotherapy focuses on pain control and range of motion with specific stretching exercises that addresses postural abnormalities and muscle imbalance relieves symptoms in most patients with thoracic outlet syndrome by relieving pressure on the thoracic outlet.  Once pain control and cervical motion are regained, strengthening exercises of the lower scapular stabilizers are begun, as is an aerobic conditioning program.   When surgery is performed, best results do appear to be in those where appropriate physiotherapy is undertaken. 


Postural correction focuses on positions of most risk and least risk for compression, with integration into the patient’s activities of daily living at work, home, and sleep.    Splints sometimes are useful.   In addition, the impact of obesity and general physical conditioning should be assessed.



1. Venous Thoracic Outlet Syndrome as a Cause of Intractable Migraines.

Chahwala V1Tashiro J1Li X2Baqai A1Rey J1Robinson HR1.

  1. Thoracic Outlet Syndrome

Narra, C.

  1. Thoracic Outlet Syndrome

Rosenbaum, D.A., Thornburg, M.,Silvis,M.L.,

  1. Thoracic Outlet Syndrome (TOS)

Sheil, W.C.

  1. A Comprehensive Review of Paget-Schroetter Syndrome,

Illig,k., Doyle, A.:

Journal of Vascular Surgery, Volume 51, Issue 6, June 2010,

  1. De Silva, M. The Costoclavicular Syndrome: a “new cause.”

Annals of Rheumatic Diseases, 1986; 45, 916-920

  1. Falconer, M., Weddel,G.,Costoclavicular Compression of the Subclavian Artery and Vein.

Lancet, 1943: ii: 539-44


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