What is Carpal Tunnel Syndrome?

Carpal tunnel syndrome occurs when tendons or ligaments in the wrist become enlarged, often from inflammation, after being aggra-vated. The narrowed tunnel of bones and liga-ments in the wrist pinches the nerves that reach the fingers and the muscles at the base of the thumb. The first symptoms usually appear at night. Symptoms range from a burning, tingl-ing numbness in the fingers, especially the thumb and the index and middle fingers, to difficulty gripping or making a fist, to drop-ping things. Some cases of carpal tunnel syndrome are due to work-related cumulative trauma of the wrist. Diseases or conditions that predis-pose to the develop-ment of carpal tunnel syndrome include pregnancy, diabetes, and obesity.

Anatomy - The Median Nerve

Carpal tunnel syndrome (CTS) is a condition, which results when the median nerve does not work properly. Usually, this is thought to occur because there is too much pressure on the nerve as it runs into the wrist through an opening called the carpal tunnel. It may be easier to understand how this occurs if you understand some of the anatomy of the wrist.

The median nerve runs into the hand to supply sensation to the thumb, index finger, long finger, and half of the ring finger. The nerve also supplies a branch to the muscles of the thumb, the thinner muscles. These muscles help move the thumb and are very important in moving the thumb so that you can touch each of the other fingers. This motion is called op-position.

The carpal tunnel is an opening into the hand that is made up of the bones of the wrist on the bottom and the transverse carpal ligament on the top. Looking at a cross section of the wrist allows one to visualize the anatomy of the carpal tunnel. Through this opening called the carpal tunnel, the median nerve and the flexor tendons run into the hand. Looking a little closer, we see that the median nerve lies just under the transverse carpal ligament.

The flexor tendons are important because they allow us to move the fingers and the hand, such as when we grasp objects. The tendons are covered by a material called teno-synovium. The tenosynovium is very slippery, and allows the tendons to glide against each other as the hand is used to grasp objects. Any condition which causes irritation or inflammation of the tendons can result in swelling and thickening of the tenosynovium. As the tenosynovium covering all of the tendons begin to swell and thicken, the pressure begins to increase in the carpal tunnel because the bones and ligaments that make up the tunnel are not able to stretch in response to the swelling. Increased pressure in the carpal tunnel begins to squeeze the median nerve against the transverse carpal ligament - because the nerve is the softest structure in the carpal tunnel. Eventually, the pressure reaches a point when the nerve can no longer function normally. Pain and numb-ness in the hand begins.

One of the first symptoms of carpal tunnel syndrome is numbness in the distribution of the median nerve. This is quickly followed by pain in the same distribution. The pain may also radiate up the arm to the shoulder, and, some-times the neck. If the condition is allowed to progress, weakness of the thenar muscles can occur. This results in an inability to bring the thumb into opposition with the other fingers and hinders one's grasp.

There are many conditions, which can result in irritation and inflammation of the tenosy-novium, and eventually cause carpal tunnel syndrome. Different types of arthritis can cause inflammation of the tenosynovium directly. A fracture of the wrist bones may later cause carpal tunnel syndrome if the healed fragments result in abnormal irritation on the flexor tendons. The Key Concept to remember is that anything, which causes abnormal pressure on the median nerve will result in the symptoms of pain, numbness and weakness of carpal tunnel syndrome. Recently, physicians have begun to recognize that activities that involve highly repetitive use of the hands can result in carpal tunnel syndrome. This is thought to be caused by inflammation and swelling of the teno-synovium due to overuse.

Diagnosis

Evaluation begins by your doctor obtaining a history of the problem, followed by a thorough physical examination. Your description of the symptoms and the physical examination are the most important parts in the diagnosis of carpal tunnel syndrome. Commonly, patients will complain first of waking in the middle of the night with pain and a feeling that the whole hand is asleep. Careful investigation usually shows that the little finger is unaffected. This can be a key piece of information to make the diagnosis. If you awaken with your hand asleep, pinch your little finger to see if it is numb also, and be sure to tell your doctor if it is or is not. Other complaints include numb-ness while using the hand for gripping activi-ties, such as sweeping, hammering, or driving. The major physical findings reflect that pressure is increased in the carpal tunnel. If more infor-mation is needed to make the diagnosis, electrical studies of the nerves in the wrist may be requested by your doctor. Several tests are available to see how well the median nerve is functioning, including the nerve conduction velocity (NCV). This test measures how fast nerve impulses are conducted through the nerve.

Non-Operative Treatment

One of the most fascinating and used healing advances is the MicroLight 830 low-level laser. On Feb. 11, 2002, the U.S. Food and Drug Administration gave the MicroLight Corpor-ation of America, market clearance for their ML830Є Cold Laser to be used in the non-surgical treatment and management of carpal tunnel syndrome, or "CTS."