Carpal tunnel syndrome is one of the most common hand conditions. It is caused by pressure on the median nerve in the carpal tunnel. The carpal tunnel is a narrow passageway in the wrist. It is on the palm side of the hand.

When the median nerve becomes compressed in the carpal tunnel, symptoms can include numbness, tingling and weakness in the fingers and hand.

Wrist structure, health conditions and repeated hand motions may play a part in carpal tunnel syndrome.

Proper treatment often lessens the tingling and numbness and restores hand function.

Symptoms of carpal tunnel syndrome tend to start slowly and include:

• Tingling and numbness. Tingling and numbness may occur in the fingers or hand and come and go. Most of the time, the thumb, index, middle and ring fingers are affected, but not the little finger. You might have a feeling like an electric shock in these fingers. These symptoms often happen while holding a steering wheel, phone or book, or they may wake you from sleep.

  The feeling also can travel from the wrist up the arm.

  Many people "shake out" their hands to try to lessen their symptoms. The numb feeling may become constant over time.

• Weakness. People with carpal tunnel syndrome may have weakness in the hand and drop objects. This may be due to numbness or to a lack of strength in the thumb's pinching muscles, which the median nerve also controls.

When to see a doctor

See a healthcare professional if you have symptoms of carpal tunnel syndrome that get in the way of your usual activities and sleep patterns. Lasting nerve and muscle damage can occur without treatment.

Carpal tunnel syndrome is caused by pressure on the median nerve.

The median nerve runs from the forearm through a passageway in the wrist to the hand. The passageway is known as the carpal tunnel. The median nerve provides feeling to the palm side of the thumb and all the fingers except the little finger. This nerve also provides signals to move the muscles around the base of the thumb. This movement is known as motor function.

Anything that squeezes or irritates the median nerve in the carpal tunnel space may lead to carpal tunnel syndrome. A broken wrist can narrow the carpal tunnel and irritate the nerve. Rheumatoid arthritis or other diseases can cause swelling that puts pressure on the nerve.

Many times, there is no single cause of carpal tunnel syndrome. Or the cause may not be known. It may be that a mixture of risk factors plays a part in the condition.

Many factors have been linked with carpal tunnel syndrome. Although they may not cause carpal tunnel syndrome directly, they may raise the risk of irritation or damage to the median nerve. These include:

• Physical factors. A broken or dislocated wrist can change the space within the carpal tunnel. So can arthritis-related changes to the small bones in the wrist. These changes can put pressure on the median nerve.

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

• Sex assigned at birth. Carpal tunnel syndrome is more common in women. This may be because the carpal tunnel area tends to be smaller in women than in men. Or it may be due to the effect of hormones on the lining of the tendons in the carpal tunnel.
• Nerve-damaging conditions. Some chronic illnesses, such as diabetes, increase the risk of nerve damage, including damage to the median nerve.
• Inflammatory conditions. Rheumatoid arthritis, gout and other inflammatory conditions can cause swelling in the tendons in the wrist. This can put pressure on the median nerve.
• Medicines. Some studies have shown a link between carpal tunnel syndrome and anastrozole (Arimidex), a medicine used to treat breast cancer.
• Obesity. Having obesity is a risk factor for carpal tunnel syndrome.
• Fluid retention. When the body holds on to extra fluid, that fluid may increase the pressure within the carpal tunnel and irritate the median nerve. This is common during pregnancy and menopause. Carpal tunnel syndrome that happens during pregnancy tends to get better on its own after pregnancy.
• Other medical conditions. Certain conditions, such as thyroid conditions and kidney failure, may raise the chances of getting carpal tunnel syndrome.

• Workplace factors. Repeated movements that flex the wrist may create pressure on the median nerve. Examples include working with vibrating tools or on an assembly line. Such work also may worsen existing nerve damage. Pressure on the nerve can be worse if the work is done in a cold environment.

  But evidence is not clear, and these factors haven't been proved as direct causes of carpal tunnel syndrome.

  Many studies have explored whether there is a link between computer use and carpal tunnel syndrome. Some evidence suggests that mouse use, but not the use of a keyboard, may be related to carpal tunnel syndrome. There has not been enough evidence to support computer use as a risk factor for carpal tunnel syndrome. But computer use may cause a different form of hand pain.

To diagnose carpal tunnel syndrome, a healthcare professional may ask you questions about your symptoms. You also may need one or more tests to find out whether you have carpal tunnel syndrome.

• History of symptoms. The pattern of your symptoms is important in making a diagnosis. Carpal tunnel syndrome symptoms often occur while holding a phone or a book or gripping a steering wheel. They also tend to occur at night and may wake you from sleep. Or you may notice the numbness when you wake up in the morning.

  But the median nerve doesn't provide feeling to the little finger. If you have symptoms in that finger, you may have a condition other than carpal tunnel syndrome.

• Physical exam. Your healthcare professional tests the feeling in the fingers and the strength of the muscles in the hand.

  Bending the wrist, tapping on the nerve or simply pressing on the nerve can trigger symptoms in many people.

• X-ray. You may need an X-ray of the affected wrist to exclude other causes of wrist pain, such as arthritis or fracture. However, X-rays are not helpful in making a diagnosis of carpal tunnel syndrome.
• Ultrasound. An ultrasound of the wrist provides a picture of the tendons and nerves. This can help show whether the nerve is being compressed.
• Electromyography. This test measures the tiny electrical discharges produced in muscles. During this test, a thin-needle electrode is placed into specific muscles to check the electrical activity when muscles contract and rest. This test can detect damage to the muscles controlled by the median nerve. The test also may rule out other conditions.
• Nerve conduction study. In this test, two electrodes are taped to the skin. A small shock is passed through the median nerve to see if electrical impulses are slowed in the carpal tunnel. This test may be used to diagnose the condition and rule out other conditions.

These steps may provide short-term symptom relief:

• Take short, frequent breaks from repetitive actions that involve the use of the hands.
• Lose weight if you are overweight or have obesity.
• Rotate the wrists and stretch the palms and fingers.
• Take a pain reliever, such as acetaminophen (Tylenol, others), aspirin, ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve).
• Wear a snug, not tight, wrist splint at night. You can buy these without a prescription at most stores that sell medicine and other healthcare products.
• Do not sleep on your hands.

If pain, numbness or weakness lasts, see your healthcare professional.

Alternative therapies may help you manage carpal tunnel syndrome. You may have to try them out to find a treatment that works for you. Always check with a healthcare professional before trying any complementary or alternative treatment.

• Yoga. Yoga postures that strengthen, stretch and balance the upper body and joints may reduce pain and improve grip strength.
• Hand therapy. Early research suggests that certain physical therapy and occupational therapy techniques for the hand may reduce symptoms of carpal tunnel syndrome.

You may start by seeing a member of your healthcare team. Depending on your symptoms, you may be sent to a doctor who has specialized training in nerve conditions, called a neurologist, or to a surgeon who specializes in treating the hands.

What you can do

To get ready for your appointment, make a list of:

• Your symptoms, including when they are at their worst. Does any activity seem to make your symptoms worse? Do you notice your symptoms at a certain time of day?
• Things you've tried to make the symptoms better.
• Key personal information, including major stresses, recent life changes and family medical history.
• All medicines, vitamins or other supplements you take, including the doses.
• Questions to ask your healthcare team.

What to expect from your doctor

Your healthcare professional may ask:

• How long have you had the symptoms?
• Did the symptoms come on all at once or develop over time?
• Are they getting better, getting worse or staying the same?
• Are there certain things you do that seem to cause the symptoms? Does anything seem to make them feel better or worse?

What you can do in the meantime

There are some simple things you can do before you see a healthcare professional for the first time.

First, try to learn whether certain things you do seem to make your symptoms worse. Change how you do those things or don't do them, if possible. For example, if driving seems to cause symptoms, try changing where you place your hands on the steering wheel.

You also might try using a wrist splint at night to see if that helps.