Everything to Know About Thoracic Outlet Syndrome

Medically Reviewed By Darragh O'Carroll, MD
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Thoracic outlet syndrome (TOS) references several disorders that develop when the blood vessels or nerves in the lower neck and upper chest are compressed. This results in neck, arm, and shoulder pain. Causes range from injury to tumors and even pregnancy, among others. Treatment is specific to the cause and is often successful. 

This article describes the three types of TOS, the symptoms and causes, and how doctors approach treatment.

What is thoracic outlet syndrome?

illustration of thoracic outlet syndrome under the shoulder, displaying the brachial plexus bundle of nerves, muscles, blood vessels, rib, and clavical
Thoracic outlet syndrome occurs when vessels or nerves become compressed. Medical illustration by Maya Chastain

TOS occurs when nerves and blood vessels between the neck and the first rib are compressed. The symptoms include shoulder, neck, and arm pain.

The compressed nerves could be located between the neck and shoulder muscles or between the collarbone and the first rib.

TOS is more common in women than men and typically begins between ages 20 and 50. 

What are the three types of TOS?

TOS is separated into three categories based on symptoms and causes. However, it is not uncommon to experience a mixture of all three types of TOS. This is because compression can occur in more than one location. 

Neurogenic thoracic outlet syndrome

Neurogenic TOS involves the nerves originating in the spinal cord. The bundle of nerves is the brachial plexus. They are responsible for muscle movement and feeling in the shoulder, arm, and hand. Neurogenic TOS is the most prevalent type, accounting for about 95% of cases, according to a 2014 review.

Venous thoracic outlet syndrome

Venous TOS is compression of the veins in the collarbone. It can lead to blood clots. Venous TOS is the second most common type of TOS, accounting for between 3–5% of cases. 

Arterial thoracic outlet syndrome

The least common form of TOS, arterial TOS is compression of an artery under the collarbone. This can lead to an aneurysm, or bulging of the artery. This form accounts for 1–2% of people diagnosed with TOS. 

What are the symptoms of thoracic outlet syndrome?

TOS symptoms vary by type. Symptoms may worsen when you lift your arm above your shoulder. You may also have less range of motion than usual.

Symptoms of neurogenic TOS

A primary sign of neurogenic TOS is Gilliatt-Sumner hand. This is atrophy of flesh at the base of the thumb. Atrophy is a deterioration of tissue, such as muscle. Other symptoms include

  • tingling or numbness in hand and fingers
  • cold hands
  • change in hand color
  • pain in shoulder, neck, arm, and armpit

Symptoms of venous TOS

Symptoms of venous TOS are similar to those of neurogenic TOS. They include:

  • weak or no pulse in arm
  • cool arm
  • pale pallor of arm
  • tingling or numbness
  • pain and aches
  • weakness in neck or arm
  • swelling 

Symptoms of arterial TOS

Symptoms of arterial TOS include: 

  • change in skin color
  • cold sensitivity in fingers and hands
  • heavy feeling in fingers and hands
  • swelling 

When to see a doctor

If you are experiencing any symptoms of TOS that recur consistently or do not subside quickly, contact a healthcare professional for an evaluation. 

You should also seek medical care if your symptoms occur following an injury.

What causes thoracic outlet syndrome?

There are many possible causes of TOS including: 

  • injury
  • tumors 
  • poor posture 
  • differences in anatomy
  • pregnancy 
  • repetitive movement and activity using the shoulders and arms, such as when playing sports or working

How do you diagnose thoracic outlet syndrome?

Your healthcare professional will gather your full medical history and perform a physical examination. TOS symptoms can be due to other conditions, such as cervical spondylosis.

To determine if your symptoms are due to TOS, your doctor may ask you to perform the elevated arm stress test. Holding your arms over your head, you open and close your fists for about 3 minutes. This may reproduce or temporarily worsen your symptoms if they are due to TOS. Pressing on the scalene muscles in your neck may also produce symptoms.

Another diagnostic TOS test is a scalene muscle block, which is an injection of an anesthetic. This should alleviate your symptoms if you have neurogenic TOS.

You also may undergo the following tests:

How do you treat thoracic outlet syndrome?

A combination of treatment methods may be necessary to alleviate TOS. 

Physical therapy

Physical therapy and an exercise program are effective methods for treating some causes of TOS. For instance, improving posture, stretching muscles, and strengthening shoulder and chest muscles to support the collarbone can be beneficial in removing pressure on the nerves and blood vessels in the neck, shoulders, and upper chest. 


Medications for TOS include: 

  • nerve pain relief:
    • nonsteroidal anti-inflammatory drugs (NSAIDs) such as naproxen (Aleve) and ibuprofen (Advil, Motrin)
    • muscle relaxers
    • anticonvulsants
  • thrombolytics, which disrupt blood clots
  • anticoagulants, which prevent blood clots


Surgical treatment could include:

  • thoracic outlet decompression, which releases or removes the structure, possibly a muscle or the first rib, compressing the nerve or blood vessel
  • blood clot removal 
  • replacement of a damaged artery 

You may be a candidate for surgery if conservative treatment, such as physical therapy for 4–6 months, has not been effective enough.

Lifestyle and self-care

Steps you can take at home to help prevent or reduce TOS include:

  • performing exercises to strengthen the muscles in your shoulders and upper chest
  • stretching your neck, shoulder, and chest muscles frequently
  • maintaining good posture
  • modifying your work station to avoid bad posture
  • maintaining a moderate weight
  • avoiding or limiting repetitive movements that aggravate the neck, shoulders, and upper chest
  • avoiding carrying heavy bags over your shoulder
  • using a heating pad when the thoracic area feels tight or aches

Thoracic outlet syndrome exercises and stretches

Four TOS exercises that could help strengthen the thoracic area include:

  • Shoulder rolls: Shrug your shoulders in a circular motion, going forward and then backward.
  • Neck stretch: Place your left hand over your head and rest it on the right side, with your right hand behind your back. Gently pull your head to the left until you feel a stretch on the right side. Hold for 5 seconds. Change hands and repeat on the opposite side. 
  • Neck retraction: With your jaw level, lean your head straight back, and hold for 5 seconds. 
  • Corner stretch: Standing approximately 1 foot from a corner, place your hands on each wall at shoulder height. Lean forward until you feel a stretch in the chest. Hold for 5 seconds. 

These TOS exercises are from the American Academy of Orthopaedic Surgeons. They recommend performing 10 repetitions of each twice daily. Contact your own doctor before performing them. Also, stop the movement if it is painful.

How serious is thoracic outlet syndrome?

The prognosis for TOS varies based on the specific type and severity of compression. Exercise and physical therapy treatment can improve TOS in most people.

Some people with neurogenic TOS and vascular TOS, venous or arterial TOS, will need surgery to relieve compression and symptoms.

Without treatment, TOS could lead to complications such as: 

  • permanent arm swelling
  • chronic pain 
  • ischemic ulcer from reduced blood flow to fingers
  • gangrene
  • blood clots
  • pulmonary embolism 
  • permanent nerve damage 

Frequently asked questions

Darragh O’Carroll, M. D., reviewed the following questions.

What does thoracic outlet syndrome feel like?

With TOS, you may feel a “pins and needles” sensation or numbness when elevating your arms with your fingers outstretched. You also may experience pain in your neck, shoulder, and arm.

Which fingers are affected by thoracic outlet syndrome?

TOS could affect all fingers. Some people report symptoms in only certain fingers, especially the fourth and fifth fingers.

Does thoracic outlet syndrome show up on an MRI scan?

Doctors use MRI scans to look at and evaluate the muscles, blood vessels, tendons, and bones for evidence of compression. TOS will also show up on CT scan with a contrast agent to highlight blood vessels and other structures.


TOS develops when nerves and blood vessels in the thoracic outlet are compressed, leading to pain in the lower neck and upper chest, as well as tingling or numbness. Additional symptoms of venous or arterial TOS include swelling, change in skin color, and heaviness. Medication may be necessary for symptoms, but TOS often resolves with exercises and physical therapy. More serious TOS may require surgery.

If you have symptoms of TOS, contact your physician right away for an examination. 

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Medical Reviewer: Darragh O'Carroll, MD
Last Review Date: 2022 Sep 30
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