Numbness and tingling to your hand can be the result of a number of problems. The most common cause of tingling and numbness to the thumb, index and middle finger is carpal tunnel syndrome. Carpal tunnel syndrome refers to a problem related to compression of the median nerve at the level of the wrist. Compression of the median nerve will cause tingling and numbness in the thumb, index, middle and half of the ring finger and occasionally coordination disturbances in the muscles at the base of the thumb.
A thick ligament called the carpal ligament forms the roof of the carpal canal. The flexor tendons and the median nerve run through the carpal canal. Increased carpal canal pressure produced by thickening of the tissues in the carpal canal or by wrist movements or finger bending can increase pressure on the median nerve.
You probably have felt the effects of nerve compression – when your foot falls “asleep” or when you hit your “funny bone.” The changes in the nerve produced by compression will progress with increased force of compression and/or length of time.
The changes that occur in the nerve will be reflected in the symptoms that you feel in your hand. In the early stages of nerve compression, your symptoms will be relatively mild and occur only occasionally. It will take more pressure on the nerve for a longer period of time before you feel any symptoms. For example, at the beginning you may feel only tingling and/or numbness at night after you have been sleeping with your wrists bent. Then, as the nerve compression progresses, the tingling and/or numbness to your hand will occur more often with less time in irritating positions. When the nerve compression is severe, the numbness will be fairly constant and you may have weakness or wasting in the muscles supplied by that nerve.
The median nerve at your wrist can be exposed to increased pressure when the wrist is bent down or extended up. Some conditions such as pregnancy can cause temporary symptoms of carpal tunnel syndrome; the symptoms usually go away after the pregnancy. Other conditions such as diabetes, hypothryroidism, rheumatoid arthritis, alcoholism and obesity can increase your risk of developing carpal tunnel syndrome. Some people have a hereditary tendency toward developing nerve compression.
The first strategy of treatment is to understand the activities and positions that irritate your symptoms and then try to avoid these positions. Some doctors may prescribe vitamin B6 in addition to splinting. A cortisone injection sometimes is recommended to decrease inflammation, but if it is successful in relieving your symptoms, the tingling/numbness likely will return within a few months.
If nonoperative treatment is going to be successful in relieving symptoms, you will notice a decrease in your symptoms within four to six weeks. If you do not notice any relief, surgical release of the carpal ligament is recommended.
The surgery for carpal tunnel syndrome consists of taking pressure off the median nerve by dividing the carpal ligament. If surgery is not performed, the pressure on the median nerve will continue and slowly, even over years, cause more numbness to your thumb, index finger, middle finger and part of the ring finger. Therefore, there is no urgency to have surgery for carpal tunnel syndrome unless you have had a trauma to your arm with a sudden onset of symptoms.
The operation to release the carpal tunnel and to decompress the median nerve involves an incision in the palm, and it usually is done on an outpatient basis with an anesthetic to just your arm. Some surgeons will do an endoscopic release of the ligament. This technique is associated with less early incisional pain but appears to have a higher incidence of nerve injury. After the incision is closed, a bulky dressing is placed on your arm to keep your wrist in a neutral position for two to three days.
As with any surgery, there are risks and complications that can occur with carpal tunnel surgery. There will be a scar on your hand, and in some cases, this may extend into your forearm. Occasionally, some patients will develop scar sensitivity or stiff, swollen hands. You may have excessive bleeding that may result in a hematoma (collection of blood underneath the skin). In most cases, this will reabsorb without any treatment, but sometimes it may be necessary to aspirate the hematoma. There is a risk of infection. There is also the risk of injury to the median nerve or one of the surrounding nerves.
Your hand and wrist will be placed in a bulky dressing that goes from your hand to your forearm, leaving your thumb, fingers and elbow free to move. Two to three days following surgery, the bulky dressing is removed, and you will be instructed in range-of-motion exercises for your hand, wrist, elbow and shoulder. The majority of patients will regain full function of their hand within a couple of months, although the incision may remain tender for many months while the scar tissue at the incision matures.
To make an appointment with a Washington University plastic and reconstructive surgeon, call 314-362-7388.
More information on treatment of peripheral nerve injuries is available on the Center for Nerve Injury & Paralysis website.