What causes Thoracic Outlet Syndrome?
TOS is most often produced by hyperextension neck injuries. Whiplash injuries from auto accidents and repetitive stress in the workplace are the two most common causes. 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. An extra rib in the neck occurs in less than 1% of the population. People born with this rib, called a "cervical rib", are 10 times more likely to develop symptoms of TOS than other people. However, even in men and women with cervical ribs, it usually requires some type of neck injury to bring on the symptoms.
How is Thoracic Outlet Syndrome diagnosed?
Physical examination is most helpful. Common findings are tenderness over the scalene muscles, located about one inch to the side of the wind pipe. Pressure on this spot causes pain or tingling down the arm. 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 the symptoms of pain, numbness, and tingling in the arm and hand. There is often reduced sensation to very light touch in the involved hand (this can only be detected in people with involvement on one side).
Neck or chest x-rays may show a cervical rib. 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 TOS 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 TOS will improve with stretching and physical therapy. In our experience with 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 3 year, 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%.
About Dr. Sanders
Richard J Sanders, M.D. is Board certified in both General Surgery and Vascular Surgery. He has been treating patients with TOS for over 30 years. During this time he has seen over 5000 patients with TOS and performed over 2,000 operations for this condition. Since 2005 he has treated more than 300 patients with pectoralis minor syndrome. His book, THORACIC OUTLET SYNDROME: A COMMON SEQUELA OF NECK INJURIES, was first published in 1991 and sold out its first printing. He has also authored several articles in medical journals and many chapters in surgical textbooks on the subject of TOS.