Thoracic Outlet Syndrome (TOS)

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is the compression of nerves and blood vessels in the upper chest that travel to the arms through a passage called the thoracic outlet. This often results in neck pain, shoulder pain and arm pain. Thoracic outlet syndrome affects people of all ages and genders. The condition is common among athletes who participate in sports that require repetitive motions of the arm and shoulder. This includes swimmers, rowers, baseball players and volleyball players.

Some types of TOS can be treated with physical therapy and medication. Some patients with severe or persistent symptoms may need surgery to reopen the thoracic outlet.


Types of thoracic outlet syndrome

Neurogenic (neurological) thoracic outlet syndrome 

Neurogenic TOS is characterized by compression of the brachial plexus, a network of nerves that run from your spinal cord to your upper limbs and control muscle movements and sensation in your shoulders, arms and hands. Neurogenic TOS can result in tingling, weakness and even mild skin color changes when you raise your arms overhead. This is the most common type of TOS in adults.

Venous thoracic outlet syndrome 

Venous TOS happens when the vein that drains blood from the arm, the subclavian vein is compressed as it travels under the collarbone and through the thoracic outlet. This can cause swelling, redness or make your arm feel heavy when you use it or raise it overhead. In extreme cases, venous TOS can cause clotting of the vein, resulting in significant swelling and persistent pain. This situation is called effort thrombosis, or Paget-Schroetter disease. This type of TOS often affects children.

Arterial thoracic outlet syndrome

Arterial TOS occurs when the muscles and bones surrounding the thoracic outlet rub against (impinge) the subclavian artery, the artery that supplies blood to the arm. This can result in loss of blood flow to the arm and make your arm feel cold and painful. Often this is temporary, happening only when your arm is raised. However, severe or long-term arterial TOS can damage the artery, cause clotting and require emergency medical attention. The most rare form, arterial TOS, requires surgery to decompress the thoracic outlet.

How serious is thoracic outlet syndrome?

With proper treatment, TOS is manageable condition. Although many cases of thoracic outlet syndrome are not preventable, the condition is treatable. Treatment is important to prevent serious complications.

If left untreated, TOS can cause complications, such as:

  • permanent nerve damage and other neurological complications
  • permanent arm swelling and pain, especially in patients with venous TOS
  • blood clots
  • pulmonary embolism, a life-threatening condition in which a blood clot travels to the lungs
  • gangrene, the death of tissue often caused by a loss of blood flow

How we care for thoracic outlet syndrome

Our goal in the Thoracic Outlet Syndrome Program at Boston Children’s Hospital is to return our patients to full function. This requires varying levels of intervention, depending on your particular circumstances, and ranges from physical therapy to interventional radiologic techniques to surgery, or often a combination of all three.

What are the symptoms of thoracic outlet syndrome?

Symptoms of thoracic outlet syndrome include:

  • neck pain
  • shoulder pain
  • arm pain
  • numbness and tingling of the fingers
  • impaired circulation to the extremities causing discoloration, swelling or pain

How can I reduce the symptoms?

If you have TOS, you should avoid holding your arms out or overhead for long periods. Avoid sleeping with your affected arm extended behind your head. You should also avoid repetitive motions with your arms, including lifting heavy objects repeatedly. Take rest periods at work and throughout the day to minimize fatigue.

What causes thoracic outlet syndrome?

It is not always possible to know what caused thoracic outlet syndrome. Any condition that results in enlargement or movement of the muscle, bone and other tissues near the thoracic outlet can cause thoracic outlet syndrome.

Causes may include:

  • muscle enlargement, such as from weight lifting
  • repetitive use, such as in baseball and rowing
  • injury
  • an extra rib
  • weight gain