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Thoracic Outlet Syndrome

If your arm is getting numb, it may be due to TOS.
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Written by Sourav Bose, MD.
Postdoctoral Research Fellow, Children's Hospital of Philadelphia
Medically reviewed by
Fellow in Cardiovascular Medicine, Brigham Women's Hospital
Last updated May 9, 2024

Thoracic outlet syndrome quiz

Take a quiz to find out if you have thoracic outlet syndrome.

Care Plan


First steps to consider

  • If you have signs of thoracic outlet syndrome—numbness or tingling in your hand or arm, arm weakness when doing overhead activity, or swelling or discoloration in your arms—see a healthcare provider.
  • Thoracic outlet syndrome is usually treated with physical therapy, medication (to reduce pain), or surgery (to prevent damage to blood vessels).
See care providers

Symptom relief

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  • You can help relieve discomfort with lifestyle changes and home remedies like gentle massage.
  • Pain from one type of TOS, called neurogenic TOS, can be treated with OTC medication.
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Emergency Care

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Go to the ER if you have any of the following symptoms:

  • Severe hand or arm pain
  • You can’t move your fingers or hand.
  • Your hand feels cold to the touch.

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is when nerves or blood vessels in the upper chest are compressed (squeezed). This can cause pain in your shoulder muscles and neck and numbness in your fingers.

Ribs (the top ones), scar tissue, and bands of muscle can all play a role in compressing the nerves or blood vessels. It can lead to pain and inflammation and can also cause blood clots and an aneurysm (a bulge in an artery) in the area of a compressed blood vessel.

Muscular young people who do repetitive overhead arm motions—like pitching or swimming—are more likely to develop venous and arterial TOS.

The majority of people with TOS will improve with exercise and physical therapy, though sometimes medications or surgery are needed to address blood vessel issues.

What are the three types of thoracic outlet syndrome?

Dr. Rx

Be honest with your doctor about the full range of symptoms you are experiencing, and which activities worsen them. Make sure to mention if you noticed any arm swelling, color change of the arm, numbness or tingling in any of your fingers, pain, or had any previous history of trauma or broken ribs. —Dr. Conor Coogan

  • Neurogenic TOS occurs when the nerves that lead to the muscles in the hands and arms are compressed. It typically happens after an injury (like whiplash) or from repetitive motion. Neurogenic TOS is more common in women.
  • Venous TOS is compression or clot of the subclavian vein (a large vein in the upper chest), trapping blood in the arm.
  • Arterial TOS is the least common type. It’s when the subclavian artery (a large artery in the upper chest) is compressed, preventing blood from reaching the arm.

Most common symptoms

In neurogenic TOS, the symptoms are nerve-related.

  • Pain in the upper arm.
  • Numbness and tingling in your arm and hand, usually on the pinky side of the hand. It’s often related to activity.
  • Arms feel weak when doing overhead activities.
  • Numbness and tingling worsen when doing things like brushing teeth or reaching up to a shelf.
  • Sometimes, if from an injury, there is pain in the neck and back.

In venous TOS, blood can’t leave the affected arm.

  • Arm is swollen and heavy, and sometimes can be darker in color.
  • May have numbness.
  • Blood clots sometimes develop.

In arterial TOS, blood can’t get to the affected arm. Usually, there are no noticeable symptoms until the blood stops flowing to the hand.

  • Pain in fingers and hand.
  • Possible numbness and tingling, cold fingers, and inability to move fingers and hand.

Other symptoms you may have

  • Hand and arm may continue to swell.
  • Extreme pain and/or paralysis (can’t move) of the hand.
  • Stroke-like symptoms, like vision loss, headache, or dizziness. Keep in mind, this is rare.

How do you get thoracic outlet syndrome?

Pro Tip

It is important to talk about your work and activities with your doctor. Some causes of TOS are repetitive overhead motions (throwing baseball, swinging tennis racket, hammering, etc.), which could alter the treatment plan to fit with your lifestyle. Also, if you have a history of cancer or have received radiation before—especially to your chest or armpit area—you should inform your doctor. —Dr. Coogan

Certain activities or events can make you more likely to get POS

  • An old injury involving a broken first (top) rib or collarbone.
  • Previous neck or nerve surgery in the arm.
  • Job that requires repetitive overhead motions.
  • Playing sports that involve swinging motions of the arms or strengthen the muscles of the upper chest (like baseball pitching, freestyle swimming, weightlifting).

Next steps

If you experience numbness or tingling in your hand or arm, see your primary care doctor.

If you have severe hand or arm pain, can’t move your fingers or hand, or if your hand feels cold to the touch, go to the ER  right away. You may have a blood clot, which requires emergency treatment.

Causes of TOS

There are several reasons TOS may occur.

  • A bone or muscle is compressing the nerves to the hand and arm.
  • Injury of blood vessels from repetitive motion that causes inflammation, aneurysm, or blood clot in a blood vessel that goes to the arm.
  • An anatomic predisposition, such as having an extra rib.
  • Growth of certain neck muscles due to repetitive motions that use those muscles (e.g., pitching).
  • Trauma to the upper chest area with scarring.

Pro Tip

Since there are different types of TOS, it is usually best to see a doctor to help identify the cause. Treatment options are different depending on the underlying cause. —Dr. Coogan


Depending on the type of TOS, you may be treated with physical therapy, medication (to reduce pain), and/or surgery (to prevent damage to blood vessels). If you have a blood clot, you may be prescribed an anticoagulant (blood-thinner) pill or injection after surgery that you would take for several months.

Neurogenic TOS

  • You may have an X-ray, CT, or MRI scan of your chest to rule out any other causes. An electromyogram might also be used to check the nerves in your arm.
  • You may be treated with local numbing medication or Botox injections in your chest muscles. The doctor may also prescribe oral pain medication and physical and occupational therapy.
  • If you don’t improve after several months, you may need surgery.

Venous TOS

  • You will need an ultrasound or contrast study of the veins of your chest and arm.
  • Depending on the number of clots, you may need an anticoagulant injection via a catheter directly into the vein to break up clots. (Not everyone needs anticoagulation before surgery.)
  • You may need surgery to remove part of the first rib and surrounding muscles if this is the cause of TOS.
  • Afterward, you may need a blood thinner for up to 6 months. It can be by pill form or by injection.

Arterial TOS

  • You will need a chest X-ray and contrast CT scan of your arteries.
  • This type of TOS typically requires surgery.
  • For a mild case, treatment is similar to that of venous TOS treatment. A blood thinner is injected into the artery. Part of the first rib and muscles around it are removed. You’re put on blood thinners for at least several months.
  • If you have a severe case—hand is cold, can’t move it, and it doesn’t have a pulse—you need emergency surgery. The doctor will remove blood clots. You may need a bypass or a synthetic graft to fix the artery.
  • If the inflammation is very severe, additional incisions (cuts) will be made in the arm. This will help relax muscles.

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Follow up

You’ll need a follow-up appointment with your doctor or vascular surgeon (surgeon who treats blood vessels) if you had venous or arterial TOS. Your doctor may ask you to come in to check that incisions are healing. Your doctor may also do ultrasounds or CT scans of your arm and chest to check blood flow.

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Fellow in Cardiovascular Medicine, Brigham Women's Hospital
Dr. Varshney is a board-certified Internist and current Cardiovascular Medicine Fellow at Brigham and Women's Hospital / Harvard Medical School. He earned his undergraduate degree in Biomedical Engineering from Washington University in St. Louis (2010) and graduated first in his class from the University of Texas Southwestern Medical School (2014). He then completed an internal medicine residency...
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