Thoracic Outlet Syndrome

by Christina Lasich, MD Health Professional

Thoracic Outlet Syndrome (TOS) is nothing short of an elusive condition that baffles many doctors. Two types of TOS exist. One type is caused by an intermittent irritation to the nerves at the point of the thoracic outlet. The other type is caused by a disruption of the normal blood flow into the arm at the point of the thoracic outlet. This discussion will focus on the "neurogenic" thoracic outlet syndrome, not the vascular thoracic outlet syndrome.

Many nerves leave from the cervical spinal cord and pass through the thoracic outlet on their way down the arm. The lower cervical nerves (C8-T1) are particularly susceptible to pressure in this small outlet formed by a roof of the collar bone and the floor of a rib. Put a little pressure on a nerve and it will get very angry. But why is this condition so elusive and baffling? Dr. James Cyriax summed it up best: "intermittent pressure on a nerve trunk may never result in the development of the neurological deficit that would be expected sooner or later to clarify the diagnosis." The intermittent nature of Thoracic Outlet Syndrome is virtually immeasurable or testable; thus, doctors have a hard time detecting the presence of this type of nerve irritation which commonly affects middle aged women.

Teresa is a 49 year old woman who wakes up every night with a sensation of pins and needles going down each arm, all the way into the hands. This sensation goes away when she gets up and starts moving around. Lately, she has been experiencing an aching sensation in her forearms. All of the symptoms get worse when she uses her arms a lot during the day. Sometimes, she will get pain, numbness and tingling when she is carrying something heavy. Her doctor seems baffled and so is she.

Thoracic Outlet Syndrome is a diagnosis primarily based on symptoms. The nocturnal sensations are common because pressure is relieved from the nerves when the body is lying down. As the pressure gets relieved from the nerves, the "pins and needles" feeling is felt. Just like when someone sits with his/her legs crossed too long and goes to stand up; the rush of sensation can be very intense. With more pressure from activity during the day, the sensations become worse at night. Sometimes these sensations can be provoked by a thorough physical examination. But why is this condition more common in women than in men? And why is this condition commonly found during middle-aged folks? The answer to both of those questions is the fact that Thoracic Outlet Syndrome is associated with drooping shoulders. Women's shoulders are prone to droop towards the floor more than men's shoulders. The muscle weakness that causes the shoulders to droop becomes prominent as one ages and gains more weight in the arms. So, Thoracic Outlet Syndrome is a condition found in overweight, middle-aged women (and some men) with drooping shoulders and little strength to hold up the weight of their own arms.

Finally, Teresa found a doctor who understands what is happening to her. She is not too happy to hear that she has a "syndrome" because that word is vague and sounds permanent. With some reassurance, her doctor tells her that Thoracic Outlet Syndrome is reversible with the right plan.

What is a good treatment plan for treating Thoracic Outlet Syndrome? The key to treating TOS is to eliminate the drooping shoulders. In order to improve one's ability to hold the arms up and keep the shoulders from sagging towards the ground, reducing the weight of the arms is very important. Less weight reduces the load on the fatigued and weakened shoulder muscles. This goal calls for body weight reduction via good nutrition and exercise. The exercises should not only target a good aerobic program, but should also target strengthening the shoulder muscles like: the trapezius and the rhomboids. Postural habits must also be changed because strength is useless unless it is properly used. Good postural habits start by holding the shoulders in a slightly shrugged position especially when carrying something over the shoulder (like a heavy purse) or holding something heavy in the arms. Until someone can build strength and lose the excess weight in order to support the arms naturally, another weapon to keep the pressure off the thoracic outlet must be deployed-armrests. That's right; supporting the arms with armrest also takes the pressure off the sensitive nerves in the thoracic outlet. Many types of armrests can help: chairs, pillows, and articulating arm supports attached to a desk. Ultimately, a treatment plan for Thoracic Outlet Syndrome is designed to reduce the pressure on the nerves that are enclosed in the thoracic outlet.

Because Thoracic Outlet Syndrome is so elusive and baffling, it is worthwhile mentioning that other conditions may be incorrectly identified as TOS or may not be correctly identified as TOS. A cervical disc herniation with radiculopathy can closely mimic TOS or exist along with TOS. Ulnar nerve entrapment (Cubital Tunnel Syndrome) or median nerve entrapment (Carpal Tunnel Syndrome) can also mimic TOS. Even tendonitis, like Tennis Elbow, can really be a case of TOS. For this reason, someone who has persistent arm pain with abnormal sensations should see a specialist. With a careful examination, the presence of Thoracic Outlet Syndrome can become clear as day.

Christina Lasich, MD
Meet Our Writer
Christina Lasich, MD

Christina Lasich, M.D., wrote about chronic pain and osteoarthritis for HealthCentral. She is physiatrist in Grass Valley, California. She specializes in pain management and spine rehabilitation.