Thoracic Outlet Syndrome

What is Thoracic Outlet Syndrome?

Thoracic Outlet Syndrome (TOS) is a group of conditions caused by compression of the nerves or blood vessels that serve your arms.

The thoracic outlet is the passageway for these nerves and blood vessels to exit the chest between the base of the neck and the armpit towards the arms. It is surrounded by muscle, bone and other tissues. Any condition that causes insufficient room for the surrounding nerves, arteries or veins can cause Thoracic Outlet Syndrome.

People with TOS often experience symptoms like numbness in fingers or pain in the shoulder, arm and neck because the nerves and/or blood vessels in the upper chest are being compressed. It usually affects otherwise healthy, young and active people, and can be complex to diagnose because often there is no obvious specific cause or multiple possible causes and symptoms can be constant or intermittent.


What causes Thoracic Outlet Syndrome?

There are three clinical causes of TOS:

  1. Compression of nerves, the subclavian artery or subclavian vein on the side of the throat or upper chest

  2. Injury to the artery due to a neck rib abnormality or other bony irritation

  3. Injury or compression of the vein which leads to a progressive narrowing and possibly a clot forming

Often no specific cause is able to be detected but the types of things that may cause compression or injury in the thoracic outlet include weight lifting (due to increased muscle mass), weight gain or obesity, rare tumours at the top of the lung or an extra rib extending from the neck (cervical rib).


What are the symptoms of Thoracic Outlet Syndrome?

People with TOS may experience a combination of the following symptoms:

  • Pain in the neck, shoulder, arm, hand or fingers

  • Numbness in the fingers

  • Impaired circulation and/or flushed sensations to the extremities causing discoloration

  • Weakness in the arms

  • Symptoms may appear or get worse when the arm is positioned above the shoulder or extended

  • Symptoms can range from mild and intermittent to severe and constant

How is Thoracic Outlet Syndrome diagnosed?

A vascular surgeon will speak to you about your symptoms, medical history and perform a range of physical examinations to explore your symptoms further. For example, certain movement of the arm and neck can produce symptoms. Further clinical tests can be used to detect TOS and provide more information about recommended treatments. These include:

  • CT or MRI scans

  • Catheter-based arteriography or venogram

  • Stress testing – placing the arm or head in certain positions to replicate symptoms

  • An anaesthetic block injection can temporarily improve symptoms and help with a diagnosis


How is Thoracic Outlet Syndrome treated?

Your vascular surgeon will usually recommend a combination of medical and physical treatments.   Some patients with severe, resistant symptoms may need surgery to open the thoracic outlet and remove the first rib to prevent further injury to the affected nerve and blood vessels from ongoing compression. TOS that affects the vascular system (veins and arteries) is more likely to require surgery to resolve the symptoms.


  • Physical therapy and injections to relieve muscle spasm may resolve your symptoms. 

  • For severe and persistent symptoms, a procedure called thoracic outlet decompression is the next step. 

  • Ongoing medication (eg anti inflammatory and muscle relaxants) may be prescribed if surgery is not suitable.


  •  Thoracic outlet decompression is usually recommended to further investigate the condition.

  • An arterial bypass may be part of this surgery depending on the level of damage to the artery.


  • Thoracic outlet decompression may be recommended to further investigate the condition.

  • If there is a clot in the vein, you may be directed to have thrombolytic therapy.  

  • You may also benefit from some type of vein reconstruction: angioplasty, patch angioplasty, or venous bypass.


How do I prevent Thoracic Outlet Syndrome?

You may be able to prevent TOS by maintaining relaxed tissues of the upper chest and avoiding putting too much stress on the tissues of the thoracic outlet around the shoulders and neck. It can also be helpful to avoid sleeping with the arms extended above the head.

If you enjoy weight training, you should consider prevention exercises and stretches to loosen the tissues around the shoulders and neck. For most people, maintaining a healthy diet and lifestyle will be enough.


Have More questions about Thoracic Outlet Syndrome?

If you have questions about the causes and treatment for Thoracic Outlet Syndrome, speak to the team at Vascular Associates.