Carpal tunnel syndrome is caused by pressure on the median nerve. The carpal tunnel is a narrow passageway surrounded by bones and ligaments on the palm side of the hand. When the median nerve is compressed, symptoms can include numbness, tingling, and weakness in the hand and arm.
The anatomy of the wrist, health problems and possibly repetitive hand motions can contribute to carpal tunnel syndrome.
Proper treatment usually relieves the tingling and numbness and restores wrist and hand function.
Carpal tunnel syndrome symptoms usually start gradually and include:
Tingling or numbness. You may notice tingling and numbness in the fingers or hand. Usually the thumb and index, middle or ring fingers are affected, but not the little finger. You might feel a sensation like an electric shock in these fingers.
The sensation may travel from the wrist up the arm. These symptoms often occur while holding a steering wheel, phone or newspaper, or may wake you from sleep.
Many people "shake out" their hands to try to relieve their symptoms. The numb feeling may become constant over time.
- Weakness. You may experience weakness in the hand and drop objects. This may be due to the numbness in the hand or weakness of the thumb's pinching muscles, which are also controlled by the median nerve.
When to see a doctor
See your health care provider if you have signs and symptoms of carpal tunnel syndrome that interfere with your normal activities and sleep patterns. Permanent 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 (carpal tunnel) to the hand. It provides sensation to the palm side of the thumb and fingers, except the little finger. It also provides nerve signals to move the muscles around the base of the 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 caused by rheumatoid arthritis.
Many times, there is no single cause of carpal tunnel syndrome. It may be that a combination of risk factors contributes to the development of the condition.
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 the risk of nerve damage, including damage to the median nerve.
- Inflammatory conditions. Rheumatoid arthritis and other conditions that have an inflammatory component can affect the lining around the tendons in the wrist and put pressure on the 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 the 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 the 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.
There are no proven strategies to prevent carpal tunnel syndrome, but you can minimize stress on the 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 short, 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. Even a few minutes each hour can make a difference.
- 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 the neck and shoulder muscles and compressing nerves in the neck. This can affect the wrists, fingers and hands, and can cause neck pain.
- 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 the hands and wrists warm.
Your provider may ask you questions and conduct one or more of the following tests to determine whether you have carpal tunnel syndrome:
History of symptoms. Your provider will review the pattern of the symptoms. For example, because the median nerve doesn't provide sensation to the little finger, symptoms in that finger may indicate a problem other than carpal tunnel syndrome.
Carpal tunnel syndrome symptoms usually occur while holding a phone or a newspaper or gripping a steering wheel. They also tend to occur at night and may wake you during the night, or you may notice the numbness when you wake up in the morning.
Physical examination. Your provider will conduct a physical examination. He or she will test 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. Some providers recommend an X-ray of the affected wrist to exclude other causes of wrist pain, such as arthritis or a fracture. However, X-rays are not helpful in making a diagnosis of carpal tunnel syndrome.
- Ultrasound. Your provider may recommend an ultrasound of your wrist to get a good picture of the bones and nerve. This can help determine whether the nerve is being compressed.
- Electromyography. This test measures the tiny electrical discharges produced in muscles. During this test, your provider inserts a thin-needle electrode into specific muscles to evaluate the electrical activity when muscles contract and rest. This test can identify damage to the muscles controlled by the median nerve, and also may rule out other conditions.
- Nerve conduction study. In a variation of electromyography, 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.
Treat carpal tunnel syndrome as early as possible after symptoms start. In the early stages, simple things that you can do for yourself may make the problem go away. For example:
- Take more-frequent breaks to rest the hands.
- Avoid activities that make symptoms worse.
- Apply cold packs to reduce swelling.
Other treatment options include wrist splinting, medications and surgery. Splinting and other conservative treatments are more likely to help if you've had only mild to moderate symptoms that come and go for less than 10 months. If you have numbness in your hands, you need to see a health care provider.
If the condition is diagnosed early, nonsurgical methods may help improve carpal tunnel syndrome, including:
- Wrist splinting. A splint that holds the wrist still while you sleep can help relieve nighttime symptoms of tingling and numbness. Even though you only wear the splint at night, it can also help prevent daytime symptoms. Nighttime splinting may be a good option if you're pregnant because it does not involve the use of any medications to be effective.
Nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs, such as ibuprofen (Advil, Motrin IB, others), may help relieve pain from carpal tunnel syndrome in the short term.
There isn't evidence, however, that these drugs improve carpal tunnel syndrome.
Corticosteroids. Your provider may inject the carpal tunnel with a corticosteroid such as cortisone to relieve pain. Sometimes the provider uses an ultrasound to guide these injections.
Corticosteroids decrease inflammation and swelling, which relieves pressure on the median nerve. Oral corticosteroids aren't considered as effective as corticosteroid injections for treating carpal tunnel syndrome.
If carpal tunnel syndrome is caused by rheumatoid arthritis or another inflammatory arthritis, then treating the arthritis may reduce symptoms of carpal tunnel syndrome. However, this is unproved.
Surgery may be appropriate if symptoms are severe or don't respond to other treatments.
The goal of carpal tunnel surgery is to relieve pressure by cutting the ligament pressing on the median nerve.
The surgery may be performed with two different techniques:
Endoscopic surgery. Your surgeon uses a telescope-like device with a tiny camera attached to it (endoscope) to see inside the carpal tunnel. Your surgeon cuts the ligament through one or two small incisions in the hand or wrist. Some surgeons may use ultrasound instead of a telescope to guide the tool that cuts the ligament.
Endoscopic surgery may result in less pain than does open surgery in the first few days or weeks after surgery.
- Open surgery. Your surgeon makes an incision in the palm of the hand over the carpal tunnel and cuts through the ligament to free the nerve.
Discuss the risks and benefits of each technique with your surgeon before surgery. Surgery risks may include:
- Incomplete release of the ligament
- Wound infections
- Scar formation
- Injuries to the nerves or blood vessels
During the healing process after the surgery, the ligament tissues gradually grow back together while allowing more room for the nerve. This internal healing process typically takes several months, but the skin heals in a few weeks.
Your provider generally will encourage you to use the hand after the ligament has healed, gradually working back to normal use of the hand while initially avoiding forceful hand motions or extreme wrist positions.
Soreness or weakness may take from several weeks to a few months to resolve after surgery. If your symptoms were very severe, symptoms may not go away completely after surgery.
Lifestyle and home remedies
These steps may provide temporary symptom relief:
- Take short, frequent breaks from repetitive activities involving the use of the hands.
- Lose weight if you are overweight or obese.
- Rotate the wrists and stretch the palms and fingers.
- Take a pain reliever, such as aspirin, ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve).
- Wear a snug, not tight, wrist splint at night. You can find these over the counter at most drugstores or pharmacies.
- Avoid sleeping on the hands.
If pain, numbness or weakness recurs and persists, see your provider.
Integrate alternative therapies into your treatment plan to help you cope with carpal tunnel syndrome. You may have to experiment to find a treatment that works for you. Always check with your provider before trying any complementary or alternative treatment.
- Yoga. Yoga postures designed for strengthening, stretching and balancing the upper body and joints may help reduce pain and improve grip strength.
- Hand therapy. Early research suggests that certain physical and occupational hand therapy techniques may reduce symptoms of carpal tunnel syndrome.
- Ultrasound therapy. High-intensity ultrasound can be used to raise the temperature of a targeted area of body tissue to reduce pain and promote healing. Research shows inconsistent results with this therapy, but a course of ultrasound therapy over several weeks may help reduce symptoms.
Preparing for an appointment
Here's some information to help you get ready for your appointment and what to expect from the provider.
What you can do
- Take note of when your symptoms are at their worst. Does any particular activity seem to make them worse, or do you notice them at a particular time of day?
- Keep track of the things you've tried to make the symptoms better.
- Write down the medications you've taken to manage your symptoms.
What to expect from your doctor
Your provider will usually want to know:
- How long you've had the problem.
- If it came on suddenly or developed over time.
- If it's getting better, worse or staying the same.
- If there are certain activities that seem to cause it, make it worse or make it better.
What you can do in the meantime
If you think you may have carpal tunnel syndrome, there are some simple things you can do before you see a provider for the first time.
First, try to determine whether any activities seem to make it worse, and change how you do those or avoid them if possible. For example, if driving seems to cause symptoms, try changing the position of the hands on the steering wheel.
Also, although there is some cost involved, there is no harm in trying a wrist splint at night to see if that helps the symptoms.