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Thoracic Outlet Syndrome

What is thoracic outlet syndrome?

Your thoracic outlet is a small space in your upper chest and shoulder area between your collarbone and your first rib. Many blood vessels, muscles, and nerves that serve your arm are located in this area. Several conditions can narrow this space. If this narrowing causes unusual pressure on your nerves or blood vessels, you may develop thoracic outlet syndrome (TOS).

The symptoms of TOS may vary depending on whether the nerves, arteries, or veins in the thoracic outlet are compressed. Ninety-five percent of cases of TOS are associated with symptoms of nerve compression. Three to 4 percent of cases occur when veins, the blood vessels that return oxygen-depleted blood to the heart, become compressed. In this situation, blood clots can develop in the compressed veins and can cause arm pain and swelling. The arteries, which carry oxygen-rich blood to the arm and hand, are compressed in the remaining 1 to 2 percent of TOS cases. Long-term compression of the main artery in your arm can lead to damage to the artery resulting in weakness and enlargement or in blood clots that could move to your hand, causing hand ischemia (lack of oxygen) that, in turn, may lead to limb loss.

What are the symptoms?

Your symptoms usually depend on whether the nerves or the blood vessels have been primarily affected. Most often, more than one of these structures may be involved, so you may have more than one kind of symptom. The common symptoms you may have include swelling in your arm, weakness in your arm or hand, and a tired feeling in your arm, which can be made worse by working with your arms raised over your head. In addition, your arm or hand may tingle or feel numb because of nerve compression. You also may have pain that starts in your shoulder and runs down your arm, as well as pain in your fingertips.  Unfortunately, the symptoms of TOS are often vague and not specific.

What causes thoracic outlet syndrome?

You may be more likely to develop TOS if you have an extra rib (called a cervical rib), if you sustain trauma, such as a fracture of your collarbone or your first rib, or even if your shoulder sags because of poor posture or loss of muscle tone associated with aging. These factors can sometimes narrow the thoracic outlet.  TOS can also affect active younger adults, especially if their jobs or other activities include repeated arm lifting. This is probably because moving the arms up and out can press the collarbone against the first rib, which narrows the thoracic outlet and may worsen TOS symptoms in those people who are susceptible. Rarely, objects inserted during invasive or diagnostic procedures, such as pacemaker wires, can cause blood clots and result in TOS symptoms.

What tests will I need?

Diagnosing TOS can be complex because the symptoms of TOS are like those of many other conditions. First your physician may ask you questions about your general health, occupation, medical history, and symptoms. In addition, your physician will conduct a physical examination. Together these are known as a patient history and exam. During a physical exam, a physician will check, among other things, to see if you have decreased range of motion in your arm and shoulder, or if you have swelling in your arm or hand. Your physician may also check for a decrease in your arm pulse or blood pressure when your arms are in various positions, a test known as Adson's maneuver.  Unfortunately, this test also can be abnormal in many people who do not have TOS, and are otherwise normal.

To help determine whether or not you have TOS, your physician may order one or more of the following tests:

• Pulse volume recordings
• X-rays of the neck or shoulder;
• Doppler ultrasound;
• Nerve conduction velocity test;
• Computed tomography (CT) scan;
• Magnetic resonance imaging (MRI);
• Venography; or
• Arteriography.

How is thoracic outlet syndrome treated?

Your particular treatment will depend on the cause of TOS in your particular situation, as well as the symptoms you have. For example, if you have an extra rib clearly causing injury to, or compression of, an artery or vein in your arm, your physician may recommend treating this cause first.

Otherwise, the usual first treatment is physical therapy aimed at strengthening the supporting muscles of your thoracic outlet. Your physical therapist will recommend exercises that strengthen your shoulder muscles to take the pressure off your nerves and blood vessels.

Your physician may also prescribe medications such as muscle relaxants, non-steroidal anti-inflammatory drugs such as aspirin or ibuprofen, pain relievers, or steroids. In addition, some patients get relief by applying moist heat or massaging the affected area.

Most patients improve with the measures listed above, especially when their treatment begins in the early stages of TOS. However, if your TOS symptoms do not improve with these measures, your physician may recommend more aggressive therapy.

Your vascular surgeon may recommend TOS decompression surgery that involves removing part or all of your extra rib, if you have one, or the first rib, a process that makes more room in the thoracic outlet. Alternatively, your vascular surgeon may remove some of the small muscles that are attached to the rib and any scar tissue that may be putting pressure on nearby nerves or vessels.  Sometimes a combination of these procedures is required.

If your arm vein has been blocked by a blood clot, your vascular surgeon may remove the blood clot with a clot-dissolving medication injected directly into your arm vein (called thrombolysis) either before or, less commonly, at the time of decompression surgery.

If the artery in your thoracic outlet has become severely damaged by pressure, your vascular surgeon may need to repair it. Sometimes, if the vessel is extensively injured, your vascular surgeon must replace the damaged part of your artery with a bypass. To do this, your vascular surgeon takes a blood vessel, such as a vein, from another part of your body. He or she attaches one end of the blood vessel above the damaged part of your arm artery and the other end below it, thereby allowing blood to flow around the injured area.  In some circumstances, a plastic artery substitute, called a graft, is used to repair your damaged artery.

Your physician may also decide to perform an angioplasty procedure. To perform an angioplasty, your physician inserts a long, thin tube, called a catheter, through an artery in your arm or leg and guides it to the blocked artery in the thoracic outlet. To expand the narrowed artery, your vascular surgeon then inflates a tiny balloon that is attached to the end of the catheter.  Sometimes a stent may be required to brace the expanded artery.  Usually some form of decompression surgery is needed to keep the blood vessel from getting compressed again.

Your vascular surgeon will advise you regarding the best treatment for your particular situation.

What can I do to stay healthy?

You can improve your recovery from TOS by practicing good posture, taking frequent breaks from work to stretch, and losing weight if you are overweight. Also, if you are prone to TOS, it is wise to avoid repetitive lifting of heavy objects over your head.

		Provided by the Society for Vascular Surgery in collaboration with NorthPoint Domain

Revised August 13, 2007