What causes thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) occurs in individuals experiencing pain, numbness, tingling and/or weakness in the arm and hand due to pressure against the nerves or blood vessels that supply the arm. TOS can be brought upon by tight muscles, ligaments or bands, though is most often produced by hyperextension neck injuries, such as whiplash from auto accidents and repetitive stress in the workplace. Some of the occupations that we see causing TOS include working on assembly lines, keyboards, or 10-key pads as well as filing or stocking shelves overhead. In some people, symptoms develop spontaneously without an obvious cause.

Additionally, in rare occasions, 1% of the population, an extra rib in the neck is present. People born with this rib, called a "cervical rib,” are ten times more likely to develop symptoms of thoracic outlet syndrome than those without the extra rib. However, even in both men and women with cervical ribs, it usually requires some type of neck injury to spark symptoms.

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How is thoracic outlet syndrome diagnosed?

Physical examination by a physician is most helpful. Common findings are tenderness over the scalene muscles, located about one inch to the side of the windpipe; pressure on this spot causes pain or tingling down the arm. Also, rotating or tilting the head to one side causes pain in the opposite shoulder or arm, plus, tingling in the hand elevating the arms in the "stick-em-up" position reproduces a feeling of discomfort, numbness and tingling in the arm and hand. There is often reduced sensation to very light touch in the involved hand as well, though this comparison can only be detected in people with involvement on one side.

A neck or chest x-ray may be done as well to look for an extra, though rarely come across cervical rib that might be the reason for a given patient experiencing sensations related to thoracic outlet syndrome. Shrinkage of hand muscles (atrophy) occurs in only 1% of people with TOS, and these people will have nerve tests that show a typical pattern of ulnar nerve damage. Other diagnostic tests that are helpful are a scalene muscle block for TOS, a simple office test that involves a 15 second injection of xylocaine into the anterior scalene or pectoralis minor muscle. The tests give strong support to the correct diagnosis if within a minute or two of the injection there is good relief of symptoms and improvement in physical exam findings.

How does thoracic outlet syndrome progress?

Examination of the muscles from the necks of people with TOS demonstrates scar tissue throughout the muscle. This was caused by a neck injury stretching these muscle fibers. The tight muscles then press against the nerves to the arm (brachial plexus) producing the hand and arm symptoms. Neck pain and headaches in the back of the head may be caused by the tightness in these muscles but also can be the result of stretching muscles and ligaments along the cervical spine of the neck in cases of whiplash injury.

What are the results of treatment?

Most people with thoracic outlet syndrome will improve with stretching and physical therapy. In our experience treating over 5,000 people with TOS, less than 30% had surgery.

The improvement rate with surgery varies with the cause of the TOS. Prior to 2005, auto injuries had a success rate of about 80% while repetitive stress at work has a success rate of 65-70%. Since 2007 new techniques increased the success rate to over 85% in both groups.

Recurrent symptoms after thoracic outlet surgery are frequently due to pectoralis minor syndrome, a compression of the brachial plexus between the coracoid process the contracted Pectoralis Minor Muscle. In the past three years, more than 100 patients have been operated on for recurrence. Most of these patients received the simple operation of pectoralis minor release. A smaller number of patients required combined thoracic outlet reoperations plus pectoralis minor release. The success rate in both groups of patients has been over 70%.

Learn about our physicians

Presbyterian/St. Luke’s Medical Center is fortunate to have two outstanding, board certified vascular surgeons involved in the evaluation and treatment of thoracic outlet syndrome.

Dr. Richard Sanders, M.D. is a pioneer in TOS, treating patients with the condition for over thirty years. Dr. Sanders is the author of the book, Thoracic Outlet Syndrome: A Common Sequela of Neck Injuries, and has also written numerous articles in medical journals and many chapters in surgical textbooks on the subject of thoracic outlet syndrome.

Dr. Steve Annest is a national lecturer on thoracic outlet syndrome and has participated in an innovative and promising approach to treat patients with recurrent brachial plexus problems after thoracic outlet surgery. He treats patients from across the country suffering from Thoracic Outlet Syndrome.