You have numbness in your hand or forearm and carpal tunnel syndrome immediately comes to your mind. However, whenever I see a patient who comes in complaining of carpal tunnel syndrome, it is not usually just carpal tunnel. If you have numbness in your hand, one of the most important things to consider is which fingers are numb. Carpal tunnel syndrome occurs when the median nerve gets pinched in the carpal tunnel of your wrist. The median nerve innervates your thumb as well as the first and second fingers. A portion of your fourth finger is also innervated by the median nerve, but often times that finger doesn’t bother patients because half of the finger is innervated by the other main nerve in your hand, the ulnar nerve. So if you are experiencing numbness in the little finger, chances are VERY good you don’t have carpal tunnel syndrome.
More often than not, patients I see in my office have what is called “double crush syndrome”. This means that the nerves innervating your hand are getting pinched or irritated in numerous places. Between the neck (where the nerves exit the spine to go into the arm and hand) and the wrist, there are many possible locations for that nerve to get pinched. The nerves going into your arm and hand can have pressure put on them when they exit the spine by vertebrae that are misaligned. This makes them more sensitive to pressure further down the line. Upon exiting the spine, the nerves go under some muscles in the front of the neck called scalenes and then behind the first rib, both of which can put more pressure on the nerves. Next, the nerves go under the pectoralis tendon and into the arm, a third area where pressure can be put on the nerves. Once the nerves hit the elbow, more muscles are there that can further irritate the nerves. Then by the time the nerves hit the wrist, they are very susceptible to any compression. It’s kind of like catching a cold. You don’t catch a cold because you happen to be standing next to someone in an elevator for 5 minutes who is sick. You catch the cold because your immune system is run down by stress, lack of sleep, poor nutrition, etc. before you even step into that elevator. Stepping into the elevator with a sick person is just the last straw for an already unhealthy immune system. The same thing applies to your nerves. Your nerves are already “sick” from other compressive forces before they even get to the wrist. The carpal tunnel is just the last straw.
Double crush syndrome was first documented in the medical journal Lancet is 1973. In this journal, Upton and McComas found in 81 out of the 115 cases of carpal tunnel syndrome studied had an associated nerve compression in the cervical spine. This is why some people who have had carpal tunnel surgery can still have symptoms. Once that tendon’s cut, it no longer can pinch the nerve. Therefore, your problem was not solely in your carpal tunnel – the nerve was getting pinched in other places up the line.
So if you have or think you have carpal tunnel syndrome, you may want to have your neck and other areas checked out. You could be experiencing a double crush.