The carpal tunnel is a small passageway approximately the size of the thumb located on the palm side of the wrist. This is where the median nerve and tendons pass from the forearm into the hand. Swelling in this space puts pressure on the nerve and causes carpal tunnel syndrome. Carpal tunnel syndrome causes numbness, tingling, pain and loss of function in the hand and fingers.
Carpal tunnel syndrome is one of the best-known repetitive-stress injuries, resulting from repeating the same action over a long period of time. Computer work is often the culprit, but other repetitive motions also can cause it, such as texting, using handheld power tools, playing racket sports and even knitting.
That said, although many cases of carpal tunnel syndrome appear to be tied to repetitive movements at work or leisure, researchers haven't found a firm link. Repetitive motion can cause other disorders, such as bursitis or tendonitis, but it doesn't appear to cause carpal tunnel syndrome unless you have other risk factors.
The most common risk factor for carpal tunnel syndrome appears to be heredity. Some people simply have smaller carpal tunnels and are more prone to the problem. Certain health conditions, such as injuries, thyroid disorders, diabetes, obesity and rheumatoid arthritis, also may increase your risk for developing carpal tunnel syndrome. Women who experience fluid retention during pregnancy may develop carpal tunnel syndrome, which usually improves after childbirth.
Women are three times more likely than men to develop carpal tunnel syndrome. Additionally, the risk increases after menopause due to hormonal changes. Men are more likely to develop carpal tunnel syndrome in midlife.
Smokers have a slower recovery rate from carpal tunnel syndrome than nonsmokers.
Is it really carpal tunnel syndrome?
Don't assume you have carpal tunnel syndrome. Other conditions like tendonitis or arthritis may cause similar symptoms. A pinched nerve in an elbow or shoulder also can cause numbness in the hands. To know for sure, you need professional screening.
Two other nerve-compression conditions are similar to carpal tunnel syndrome:
- Cubital tunnel syndrome occurs when the ulnar nerve, which passes behind the elbow and down to the hand, is squeezed. This causes a tingling sensation.
- Radial nerve compression, also called resistant tennis elbow, occurs when the nerve that operates several muscles around the wrist and hand is compressed or pinched.