Thoracic Outlet Compression Syndrome (TOCS)

What is it?

The thoracic outlet is the small area between the collarbone and the first rib and contains many blood vessels, nerves and muscles.

  • Anything that exerts added pressure onto this area is likely to result in a variety of symptoms in the arm, known as Thoracic Outlet Compression Syndrome (TOCS). 
  • TOCS is a relatively uncommon condition caused by compression of the nerves, blood vessels, and occasionally both of these, as they leave the chest for the arm.
  • In 98% of cases the nerves are affected alone, specifically the brachial plexus. 
  • Sometimes the compression can put pressure onto the arterial and venous blood vessels. 
  • Occasionally a structural abnormality may be the trigger, such as being born with an extra rib.


  • TOCS can be very difficult to accurately diagnose. Many patients have seen a number of doctors before seeking specialist advice. 
  • It can appear spontaneously, through no apparent reason, or after any form of neck trauma which causes muscle spasms. However it may be many months after the trauma itself before the symptoms occur. Trauma to the area may also occur due to repetitive strain type injuries. These are often related to occupation and physical positioning. 
  • Anything which increases muscle size, particularly in sports, such as weight lifting, can potentially cause TOCS.
  • Pressure on the deep nerves (brachial plexus) can cause aching in the neck, shoulder, arm or hand. 
  • This is sometimes accompanied by numbness in the forearm and a tingling in the fingers.The symptoms are usually classically associated with specific positions of the arm, usually reaching overhead and repetitive overrhead activities. 
  • The area of compression can often be diagnosed by establishing whether the compression involves the upper or lower plexus.
    • Patients with an upper plexus problem may have symptoms in the side of their neck which can include the ear, jaw, face, temple and back of the head. This may also be present in the forearm and arm but the hand is unaffected.
    • With lower plexus involvement the symptoms can vary in intensity and tends to flow down the arm and into the hand. There may be some numbness or tingling of the ring and small finger. 
  • Aches at the side and back of the head can sometimes feel like they reach the chest area and occasionally can be misinterpreted as being cardiac in origin.
  • With blood vessel involvement there may be some swelling and redness of the arm due to reduced blood flow and occasionally, although rarely, a reduction of blood to the hand can leave the hand feeling, and looking, cold. 
  • The experienced specialist will realise the distress this causes the patient and will take time to reassure him or her of the nature of the problem. The clinical examination should include a detailed look at the neck, shoulders and arms. The pulse, muscle strength and sensation of the arm are assessed with the arm in neutral positions and also in the positions of maximal symptoms. A common test is to ask the patient to raise the arms over the head and to open and close the fists for three minutes. This may temporarily worsen the symptoms and is an important part of making an accurate diagnosis. 


  • X-rays and scans of the neck, thoracic outlet and shoulder are usually performed. 
  • If there are vascular symptoms and signs ultrasound doppler scanning and/or angiograms of the blood vessels with the arm in position of symptoms is also valuable.
  • Where there are nerve symptoms nerve conduction studies may be performed. 
  • Once a diagnosis has been made, a treatment plan arranged. There are many variations of TOCS, depending on the structures involved and treatment should be specific to the cause. This requires a diagnosis from an experienced TOCS specialist, which is usually a vascular or cardiothoracic surgeon. 


  • Physiotherapy is an important and effective treatment as it strengthens the muscles around the shoulder which enable them to support the collarbone more effectively. This has the effect of relieving some of the pressure. Postural exercises may also be given to lessen the pressure on nerves and blood vessels. 
  • Anti-inflamatories and pain killers can relieve the pain and reduce internal swelling. 
  • Lifestyle changes may be discussed, with consideration given to physical positioning at work and, maybe, the modification of everyday activities. 
  • Surgical intervention may be offered if there is a clear compressive cause. This can involve procedures such as removing part of a rib or releasing the muscle which joins the neck and chest (scalenes). This surgery is usually done by Vascular or Cardiothoracic Surgeons, not Shoulder surgeons.

 Below is a very useful video from the American Vascular Society:

More information on Physiopedia Here 

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