Thoracic Outlet Syndrome

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What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is a term that refers to three related syndromes involving compression of the nerves, arteries, and veins in the lower neck and upper chest area. This compression causes pain in the arm, shoulder, and neck. 

Symptoms of TOS vary depending on the type:

  • Neurogenic TOS has a symptom called the “Gilliatt-Sumner hand,” in which there is severe wasting (weakening) in the fleshy base of the thumb. Other symptoms may include:
    • Paresthesias (“pins and needles” sensation or numbness) in the fingers and hand
    • Change in hand color
    • Cold hands
    • Dull aching pain in the neck, shoulder, and armpit 
  • Venous TOS symptoms may include:
    • Pallor (paleness)
    • A weak or absent pulse in the affected arm, which also may be cool to the touch and appear paler than the unaffected arm
    • Numbness, tingling, aching, or swelling of the arm and fingers
    • Weakness of the neck or arm
  • Arterial TOS symptoms may include:
    • Change in color in the hands and fingers
    • Sensitivity to cold in the hands and fingers
    • Swelling, heaviness, “pins and needles” sensation or numbness, and poor blood circulation in the arms, hands, and fingers

The outlook for people with TOS varies according to type. Most people will improve with exercise and physical therapy. People with vascular TOS and true neurogenic TOS often need surgery to relieve pressure on the affected vessel or nerve.

Who is more likely to get thoracic outlet syndrome?

There are many causes of TOS, including:

  • Physical trauma
  • Anatomical defects
  • Tumors that press on nerves
  • Poor posture that causes nerve compression
  • Pregnancy
  • Repetitive arm and shoulder movements and activity, such as from playing certain sports

TOS is more common in women. Symptoms usually begin between ages 20 and 50. 

How is thoracic outlet syndrome diagnosed and treated?

Diagnosing TOS

Doctors usually recommend nerve conduction studies, electromyography, or imaging studies to confirm or rule out a diagnosis of TOS. It can be difficult to diagnose because a number of disorders have symptoms similar to those of TOS. Those disorders include:

  • Rotator cuff injuries
  • Cervical disc disorders
  • Fibromyalgia
  • Multiple sclerosis
  • Complex regional pain syndrome
  • Tumors of the syrinx or spinal cord 

TOS can sometimes be diagnosed in a physical exam by:

  • Tenderness in the area just above the clavicle or collarbone, toward the hollow of the neck
  • Weakness and/or a "pins and needles" feeling when raising the hands
  • Weakness in the fifth ("little") finger
  • Paleness in the palm of one or both hands when they're raised above the shoulders, with the fingers pointing to the ceiling

Treating TOS

Treatment begins with exercise programs and physical therapy to:

  • Strengthen the chest muscles
  • Restore normal posture
  • Relieve compression by increasing the space in the area where the nerve passes through  

Doctors will often prescribe non-steroidal anti-inflammatory drugs (such as naproxen or ibuprofen) for pain. Other medicines include:

  • Thromobolytics to break up blood clots
  • Anticoagulants to prevent clots 

If this doesn't relieve pain, a doctor may recommend thoracic outlet decompression surgery to release or remove the structures that are compressing the nerve or artery.

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with thoracic outlet syndrome?

Consider participating in a clinical trial so clinicians and scientists can learn more about TOS and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with TOS at

Where can I find more information about thoracic outlet syndrome?

The following organizations help patients, families, friends, and caregivers of people living with TOS:

American Chronic Pain Association (ACPA)
Phone: 916-632-0922 or 800-533-3231

National Rehabilitation Information Center (NARIC)
Phone: 800-346-2742

Learn about related topics

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