Carpal Tunnel Syndrome (CTS) is an occupational medical diagnosis that often gives employers, patients, and sometimes even medical providers, undue levels of frustration. Like a lot of other things in medicine, reasonably simple concepts are hidden behind Latin words. You just need a basic understanding of how things are put together – in other words, anatomy.
Let’s start with the hands. The hands are absolute miracles of micro-engineering. They are capable of generating tremendous force, while being compact and delicate enough to pay a violin. They pull this off by putting the muscles that work the fingers in the forearm. These muscles are connected by cables, called tendons, to the fingers. Contract a muscle in the forearm, it pulls the cable (tendon) and moves the finger. I never fail to be impressed by the cleverness with which the human body is put together.
Because the muscles are in one place and the hand in another, the tendons connecting the two must pass through the wrist. Where they pass through the wrist is a snug fit, and therein lies the problem. The tendons pass through a “tunnel” in the wrist, made of the arrangement of the wrist bones (carpals). This tunnel is shaped like a “U.” On the sides and floor are bones, and the roof is covered by a thick, gristly strap. Through this tunnel is where 9 tendons and the median nerve pass.
These tendons and the median nerve normally peacefully cohabitate. They are probably doing that right this minute in your body. The tendons are surrounded by lubricated jackets (like a bicycle brake cable), so they slide through the wrist with ease. If the tendons should swell because the tunnel doesn’t stretch, pressure is put on the nerve, which sometimes shorts circuits.
Since this nerve supplies the thumb, index and long fingers with sensation, these are the areas that become numb. There is also shooting pains in the wrist from pressure on the median nerve.
The most important thing to realize about CTS is this is a dynamic situation. Tendons can get more or less swollen in a matter of a few days. Sometimes all it takes to reduce swelling is a wrist brace or a change of work duties. Sometimes it takes more effort involving medication (anti-inflammatories) and physical therapy. Occasionally a cortisone shot fixes the problem. As a last resort, we cut the strap (cut the gristly hood of the carpal tunnel). This allows more room for the tendons and nerve.
It is important to treat CTS sooner rather than later. Early on, it will be easier to get the swelling out of the tendons, and the damage to the nerve will be minor and completely reversible.
Why do people get CTS, or conversely, why don’t we all have CTS? There are wide individual variations on what it takes to get a case of tendon swelling in the wrist. Some people get swelling in their wrist after one month of doing repetitive work; others will never have a problem. We do know that you narrow the carpal tunnel when your wrist is in ulnar deviation. That makes it a tighter fit and probably contributes to CTS.
Ulnar deviation is bending your wrist to the side. If you are sitting at a computer, you are doing that right this minute. This occurs because the keyboard is narrower than your shoulders; so you have to bend you wrist in ulnar deviation to line up your fingertips with the keyboard. This has caused the development of “V”-shaped ergonomic keyboards, which can be very useful in treating or preventing CTS. I am using one to type this article.
So CTS is more like a dimmer switch than a light switch. It comes in a great variety of stages. It is relatively easy to get some swelling out of a wrist and get someone healed at an earlier stage. The earlier the intervention, the more likely it will easily and quickly resolve.
Donald Bucklin, MD (Dr. B) is a Regional Medical Director for U.S. HealthWorks and has been practicing clinical occupational medicine for more than 25 years. Dr. B. works in our Scottsdale, Arizona clinic.
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