What is carpal tunnel syndrome?
Carpal tunnel syndrome is numbness, tingling, weakness, and other problems in your hand because of pressure on the median nerve in your wrist.
The median nerve and several tendons run from your forearm to your hand through a small space in your wrist called the carpal tunnel . The median nerve controls movement and feeling in your thumb and first three fingers (not your little finger).
What causes carpal tunnel syndrome?
Pressure on the median nerve causes carpal tunnel syndrome. This pressure can come from swelling or anything that makes the carpal tunnel smaller. Many things can cause this swelling, including:
- Illnesses such as hypothyroidism, rheumatoid arthritis, and diabetes.
- Making the same hand movements over and over, especially if the wrist is bent down (your hands lower than your wrists), or making the same wrist movements over and over.
- Pregnancy.
Causes
Carpal tunnel syndrome is caused by pressure on the median nerve.
The median nerve runs from your forearm through a passageway in your wrist (carpal tunnel) to your hand. It provides sensation to the palm side of your thumb and fingers, except the little finger. It also provides nerve signals to move the muscles around the base of your thumb (motor function).
Anything that squeezes or irritates the median nerve in the carpal tunnel space may lead to carpal tunnel syndrome. A wrist fracture can narrow the carpal tunnel and irritate the nerve, as can the swelling and inflammation resulting from rheumatoid arthritis.
There is no single cause in many cases. It may be that a combination of risk factors contributes to the development of the condition.
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 your chances of developing or aggravating median nerve damage. 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 with 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. Illnesses that are characterized by inflammation, such as rheumatoid arthritis, can affect the lining around the tendons in your wrist and put pressure on your median nerve.
- Obesity. Being obese is a significant risk factor for carpal tunnel syndrome.
- Alterations in the balance of body fluids. 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 resolves on its own after pregnancy.
- Other medical conditions. Certain conditions, such as menopause, obesity, thyroid disorders and kidney failure, may increase your chances of carpal tunnel syndrome.
- Workplace factors. It’s possible that 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.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. 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.
Prevention
There are no proven strategies to prevent carpal tunnel syndrome, but you can minimize stress on your hands and wrists with these methods:
- Reduce your force and relax your grip. If your work involves a cash register or keyboard, for instance, hit the keys softly. For prolonged handwriting, use a big pen with an oversized, soft grip adapter and free-flowing ink.
- Take frequent breaks. Gently stretch and bend hands and wrists periodically. Alternate tasks when possible. This is especially important if you use equipment that vibrates or that requires you to exert a great amount of force.
- Watch your form. Avoid bending your wrist all the way up or down. A relaxed middle position is best. Keep your keyboard at elbow height or slightly lower.
- Improve your posture. Incorrect posture rolls shoulders forward, shortening your neck and shoulder muscles and compressing nerves in your neck. This can affect your wrists, fingers and hands.
- Change your computer mouse. Make sure that your computer mouse is comfortable and doesn’t strain your wrist.
- Keep your hands warm. You’re more likely to develop hand pain and stiffness if you work in a cold environment. If you can’t control the temperature at work, put on fingerless gloves that keep your hands and wrists warm.
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