Risk factors

A number of factors have been associated with carpal tunnel syndrome. Although they may not directly cause carpal tunnel syndrome, they may increase the risk of irritation or damage to the median nerve. These include:

• Anatomic factors. A wrist fracture or dislocation, or arthritis that deforms the small bones in the wrist, can alter the space within the carpal tunnel and put pressure on the median nerve.

  People who have smaller carpal tunnels may be more likely to have carpal tunnel syndrome.

• Sex. Carpal tunnel syndrome is generally more common in women. This may be because the carpal tunnel area is relatively smaller in women than in men.

  Women who have carpal tunnel syndrome may also have smaller carpal tunnels than women who don't have the condition.

• Nerve-damaging conditions. Some chronic illnesses, such as diabetes, increase your risk of nerve damage, including damage to your median nerve.
• Inflammatory conditions. Rheumatoid arthritis and other conditions that have an inflammatory component can affect the lining around the tendons in your wrist and put pressure on your median nerve.
• Medications. Some studies have shown a link between carpal tunnel syndrome and the use of anastrozole (Arimidex), a drug used to treat breast cancer.
• Obesity. Being obese is a risk factor for carpal tunnel syndrome.
• Body fluid changes. Fluid retention may increase the pressure within your carpal tunnel, irritating the median nerve. This is common during pregnancy and menopause. Carpal tunnel syndrome associated with pregnancy generally gets better on its own after pregnancy.
• Other medical conditions. Certain conditions, such as menopause, thyroid disorders, kidney failure and lymphedema, may increase your chances of carpal tunnel syndrome.

• Workplace factors. Working with vibrating tools or on an assembly line that requires prolonged or repetitive flexing of the wrist may create harmful pressure on the median nerve or worsen existing nerve damage, especially if the work is done in a cold environment.

  However, the scientific evidence is conflicting and these factors haven't been established as direct causes of carpal tunnel syndrome.

  Several studies have evaluated whether there is an association between computer use and carpal tunnel syndrome. Some evidence suggests that it is mouse use, and not the use of a keyboard, that may be the problem. However, there has not been enough quality and consistent evidence to support extensive computer use as a risk factor for carpal tunnel syndrome, although it may cause a different form of hand pain.