Thoracic Outlet Syndrome

I was talking with my Dad the other evening about St. Louis Cardinals pitcher Chris Carpenter and his return from surgery to relieve his symptoms due to thoracic outlet syndrome (TOS).  This is not a very common injury, but it can lead to a lot of pain and weakness, which is obviously a major problem for a baseball pitcher.  I will outline the basic principles of TOS below.

Before talking about the syndrome, we first need to define the thoracic outlet.  If you look at the top picture, you will see a group of nerves coming out of the spinal cord, and running down between the scalene muscles, behind the clavicle, and in front of the first rib, and then down into the arm.  This group of nerves is known as the brachial plexus.  The opening between the scalene muscles and the ribcage is the thoracic outlet.  There are also blood vessels not pictured above that pass through this space.  Any time there is a nerve or group of nerves passing through a tight space, there is a chance that some of the structures can "press" on the nerves, which can lead to pain, tingling, numbness, and weakness in the affected area.  In TOS, it could be the scalene muscles, the clavicle, or the first rib pressing on the nerves.

What causes TOS?  There are many potential causes, including a fractured clavicle, tightness or scar tissue in the scalene muscles, the presence of an extra first rib (yes, some people actually have 13 instead of 12 pairs, but the presence of an extra rib does not necessarily lead to TOS), pressure from the normal 1st rib, repetitive stress, such as repeating the overhead throwing motion, or poor posture.  The signs and symptoms include pain along the side of the neck, the upper arm, and possibly the lower arm.  Numbness, tingling, and weakness in the shoulder and arm may also be present.  These symptoms are similar to other conditions, such as a herniated disc, which can make diagnosing TOS difficult.

In the case of Chris Carpenter, his TOS was likely caused due to the repetitive stress of the overhead throwing motion.  He had similar symptoms back in 2008, but they did not resurface again for several years.  His symptoms first resurfaced during spring training, when he was diagnosed with a herniated disc.  He was prescribed rest followed by strengthening exercises for the neck, shoulder, and arm.  After a couple of months of rehab, he attempted to pitch again, but could not because the pain returned.  He was then referred to a specialist who made the diagnosis of TOS and recommend surgery to remove his first rib and release some of the scar tissue around the scalene muscles (I am not sure if he had an extra first rib or not).  He has responded well since the surgery and is attempting to pitch again this year, but at the least he should be healthy to start next season (or relatively healthy for a 37 year old pitcher).

In many cases, therapy and postural changes can relieve most of the symptoms of TOS.  Surgery is often seen as a last option, because it does carry some risks since the surgeon has to operate close to many nerves.