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.