What is thoracic outlet syndrome?
Thoracic outlet syndrome (TOS) is a term used to describe a group of disorders that occur when there is compression, injury, or irritation of the nerves and/or blood vessels (arteries and veins) in the lower neck and upper chest area. Thoracic outlet syndrome is named for the space (the thoracic outlet) between your lower neck and upper chest where this grouping of nerves and blood vessels is found.
Who is affected by thoracic outlet syndrome?
Thoracic outlet syndrome affects people of all ages and gender. The condition is common among athletes who participate in sports that require repetitive motions of the arm and shoulder, such as baseball, swimming, volleyball, and other sports.
Neurogenic TOS is the most common form of the disorder (95 percent of people with TOS have this form of the disorder) and generally affects middle-aged women.
Recent studies have shown that, in general, TOS is more common in women than men, particularly among those with poor muscular development, poor posture or both.
What are the symptoms?
The signs and symptoms of TOS include neck, shoulder, and arm pain, numbness or impaired circulation to the affected areas.
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 help determine the type of disorder a patient has. Thoracic outlet syndrome disorders differ, depending on the part(s) of the body they affect. Thoracic outlet syndrome 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 is narrowed, and there is scar formation around the structures.
Types of thoracic outlet syndrome disorders and related symptoms
- Neurogenic thoracic outlet syndrome: This condition is related 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