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Thoracic Outlet Syndrome

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) occurs when the vessels and/or nerves running from the upper body to the arm become compressed, leading to swelling, reduced blood flow, tingling, weakness, pain and/or numbness in the neck, shoulder, arms, or hands. Thoracic outlet syndrome got its name from the space (the thoracic outlet) between your lower neck and upper chest where this grouping of nerves and blood vessels is located.

It is caused by trauma, repetitive movements, exertion, anatomic narrowing of the muscles or congenital conditions. If left untreated, the pain can worsen, and upper-extremity function may decrease. Certain forms of the disease can lead to limb- and life-threatening blood clots.

Who is affected by thoracic outlet syndrome?

Thoracic outlet syndrome affects people of all ages and gender. This condition is common among musicians and athletes who participate in sports that require repetitive motions of the arm and shoulder, such as baseball, swimming, volleyball, and other sports.

Recent studies have shown that, in general, TOS is more common in women, particularly among those with poor muscular development, poor posture or both.

There are three types of TOS:


Arterial, which involves compression of the subclavian artery as it exits the chest and travels to the arm.


Venous, which involves occlusion of the subclavian vein as it enters the chest cavity from the shoulder.


Neurogenic, which involves compression of one or more brachial plexus nerves running from the neck to the hands. This is the most common, 95 percent of people with TOS have this form of the disorder.

What are the symptoms?

The signs and symptoms of TOS include:

  • Neck, shoulder, or arm pain
  • Numbness in the arm, hand, or fingers
  • Impaired circulation to the extremities (causing discoloration)
  • Weakness in the shoulders, arm, and hands
  • Swelling of the entire arm and shoulder

The pain of TOS is sometimes confused with the pain of angina (chest pain due to an inadequate supply of oxygen to the heart muscle), but the two conditions can be distinguished because the pain of thoracic outlet syndrome does not occur or increase when walking, while the pain of angina usually does. Additionally, the pain of TOS typically increases when raising the affected arm, which does not occur with angina.

Signs and symptoms of TOS also help determine the type of disorder a patient has. Thoracic outlet syndrome disorders differ, depending on the part(s) of the body they affect. TOS most commonly affects the nerves, but the condition can also affect the veins and arteries (least common type). In all types of TOS, the thoracic outlet space narrows, and there is scar formation around the structures.

Types of thoracic outlet syndrome disorders and related symptoms:

  • Neurogenic thoracic outlet syndrome: This condition relates to abnormalities of bony and soft tissue in the lower neck region (which may include the cervical rib area) that compress and irritate the nerves of the brachial plexus, the complex of nerves that supply motor (movement) and sensory (feeling) function to the arm and hand. Symptoms include weakness or numbness of the hand; decreased size of hand muscles, which usually occurs on one side of the body; and/or pain, tingling, prickling, numbness and weakness of the neck, chest, and arms.
  • Venous thoracic outlet syndrome: This condition is caused by damage to the major veins in the lower neck and upper chest. The condition develops suddenly, often after unusual and tiring exercise of the arms. Symptoms include swelling of the hands, fingers, and arms, as well as heaviness and weakness of the neck and arms. The veins in the anterior (front) chest wall veins also may appear dilated (swollen).
  • Arterial thoracic outlet syndrome: The least common, but most serious, type of TOS is caused by congenital (present at birth) bony abnormalities in the lower neck and upper chest. Symptoms include cold sensitivity in the hands and fingers; numbness, pain or sores of the fingers; and poor blood circulation to the arms, hands and fingers.

What causes thoracic outlet syndrome?

The disorders caused by TOS are not well understood. Yet, it is known that when the blood vessels and/or nerves in the tight passageway of the thoracic outlet are abnormally compressed, they become irritated and can cause TOS. Thoracic outlet syndrome can be a result of an extra first rib (cervical rib) or an old fracture of the clavicle (collarbone) that reduces the space for the vessels and nerves. Bony and soft tissue abnormalities are among the many other causes of TOS.

The following may increase the risk of developing thoracic outlet syndrome:

  • Sleep disorders
  • Tumors or large lymph nodes in the upper chest or underarm area
  • Stress or depression
  • Participating in sports that involve repetitive arm or shoulder movement, such as baseball, swimming, golfing, volleyball and others
  • Repetitive injuries from carrying heavy shoulder loads
  • Injury to the neck or back (whiplash injury)
  • Poor posture
  • Weightlifting

Diagnosis and Testing

TOS can mimic other disorders and is difficult to diagnose by health providers who are not familiar with its specific symptom profile. Expert vascular specialists can identify TOS through:

  • A comprehensive medical history and physical exam
  • Stress tests to determine how long the arms and hands can be held above the head and complete certain movements
  • Examination of the anterior scalene muscle in the neck, which might be tender
  • An ultrasound scan to determine arterial compression or venous occlusion
  • Imaging studies such as X-rays and CT (computed tomography)
  • Arteriogram/venogram (X-ray that uses dye to look at blood flow)

Is thoracic outlet syndrome serious?

Although many cases of thoracic outlet syndrome (TOS) are unpreventable, the condition is treatable. If left untreated, TOS can cause complications, such as:

  • Permanent arm swelling and pain (especially in patients with venous TOS)
  • Ischemic ulcer of the fingers (open sore caused by reduced blood flow)
  • Gangrene (the death of body tissue, often caused by a loss of blood flow)
  • Blood clot
  • Pulmonary embolism (obstruction in a blood vessel due to a blood clot)
  • Neurogenic complications, such as permanent nerve damage

How is Thoracic Outlet Syndrome Treated?

Early identification of TOS can help improve the success of treatment. Thoracic outlet syndrome treatments vary, depending on the type of TOS you have and your symptoms. The goals of treatment are to reduce symptoms and pain. Your health care provider will recommend the treatment option that is right for you.

Treatment of neurogenic thoracic outlet syndrome

Physical therapy

The most common initial treatment for neurogenic thoracic outlet syndrome is physical therapy. Physical therapy increases the range of motion of the neck and shoulders, strengthens muscles, and promotes better posture.


For pain relief, over-the-counter pain medications, such as aspirin, acetaminophen (Tylenol), or ibuprofen (Motrin), may be recommended. Your doctor may prescribe a muscle relaxant for additional pain relief.


In some cases, surgery may be needed to treat neurogenic thoracic outlet syndrome if symptoms continue, despite an optimal course of physical therapy.

Treatment of venous thoracic outlet syndrome

  • To reduce the risk of blood clots and pulmonary embolism, treatment for venous thoracic outlet syndrome may include thrombolytic (clot-busting) or anticoagulant (blood thinning) medications and surgery. In many cases, the patient will be treated with thrombolytic medications and start anticoagulation therapy before surgery.
  • Thrombolytic medications are given to dissolve blood clots. This type of medication is always given to the patient in the hospital so he/she can be closely monitored. The medication(s) may be injected directly into the vein or delivered via a catheter, a long slender tube, which is guided through the vein to the area where the blood clot is located. The clot-dissolving drug is sent through the catheter into the clot. The clot usually dissolves in a matter of hours to a few days.
  • Anticoagulant medications decrease the blood’s ability to clot and keep more clots from forming. Some common anticoagulant medications include warfarin (Coumadin), and heparin.
  • Surgery may be necessary along with medications to manage your symptoms. Surgery corrects the narrowing that is causing problems with the vein and may be recommended after the clot in the vein has been effectively treated/dissolved with medications.

Treatment of arterial thoracic outlet syndrome

  • Surgery: Patients with arterial thoracic outlet syndrome often require surgical treatment. Surgery may be performed to remove the first rib and make more room for the vessels and nerves. Surgery may also be performed to repair any structural problems of the artery.
  • Thrombolytic medications may be given before surgery, if necessary, to dissolve blood clots. This type of medication is always given to the patient in the hospital so he/she can be closely monitored. The medication(s) may be injected directly into the artery or delivered via a catheter, a long slender tube, which is guided through the artery to the area where the blood clot is located. The clot-dissolving drug is sent through the catheter into the clot. The clot usually dissolves in a matter of hours to a few days.

When is surgery necessary?

Although only 10 to 20 percent of patients with TOS need surgical treatment, most patients with venous or arterial TOS will need surgical treatment.

Surgery for venous and arterial TOS is very effective. Among patients with venous TOS, elective surgery corrects symptoms in 90 to 95 percent of cases; elective surgery resolves symptoms in more than 95 percent of patients with arterial TOS.

Some patients with neurogenic TOS will need surgery. The primary goal of surgery in these patients is to remove the source of compression on the spinal nerves that supply stimulation to the arm, forearm, and hand (the brachial plexus). This is typically accomplished by removing the first rib, abnormal muscles, or fibrous bands. If there is an extra rib causing compression, it may also be removed.

Known as “decompression surgery,” the procedure is typically completed by making an incision in the underarm area on the affected side. It can also be performed through an incision made above the clavicle (collar bone). An alternative surgical approach known as video-assisted thoracoscopic surgery (VATS), which is performed through several small incisions, may be used in some cases.

Following surgery, you will stay in the hospital for one night, and in some cases an additional day. During your recovery, you will begin physical therapy to you gain function and minimize pain and the recurrence of symptoms.