Carpal Tunnel Syndrome
Carpal tunnel syndrome is a common condition that causes numbness, tingling, and pain in the hand and forearm. The condition occurs when one of the major nerves to the hand — the median nerve — is squeezed or compressed as it travels through the wrist.
Carpal tunnel syndrome (CTS) occurs when the median nerve, which runs from the forearm into the palm of the hand, becomes pressed or squeezed at the wrist. The carpal tunnel—a narrow, rigid passageway of ligament and bones at the base of the hand—houses the median nerve and the tendons that bend the fingers. The median nerve provides feeling to the palm side of the thumb and to the index, middle, and part of the ring fingers (although not the little finger). It also controls some small muscles at the base of the thumb.
Symptoms usually start gradually, with frequent numbness or tingling in the fingers, especially the thumb and the index and middle fingers. Some people with CTS say their fingers feel useless and swollen, even though little or no swelling is apparent. The symptoms often first appear in one or both hands during the night. The dominant hand is usually affected first and produces the most severe symptoms. A person with CTS may wake up feeling the need to “shake out” the hand or wrist.
Carpal tunnel syndrome is often the result of a combination of factors that increase pressure on the median nerve and tendons in the carpal tunnel, rather than a problem with the nerve itself. Contributing factors include trauma or injury to the wrist that cause swelling, such as sprain or fracture; an overactive pituitary gland; an underactive thyroid gland; and rheumatoid arthritis. Other factors that may contribute to the compression include mechanical problems in the wrist joint, repeated use of vibrating hand tools, fluid retention during pregnancy or menopause, or the development of a cyst or tumor in the canal. Often, no single cause can be identified.
Women are three times more likely than men to develop carpal tunnel syndrome. People with diabetes or other metabolic disorders that directly affect the body’s nerves and make them more susceptible to compression are also at high risk. CTS usually occurs only in adults.
At the workplace, workers can do on-the-job conditioning, perform stretching exercises, take frequent rest breaks, and use correct posture and wrist position. Wearing fingerless gloves can help keep hands warm and flexible. Workstations, tools and tool handles, and tasks can be redesigned to enable the worker’s wrist to maintain a natural position during work. Jobs can be rotated among workers. Employers can develop programs in ergonomics, the process of adapting workplace conditions and job demands to the capabilities of workers. However, research has not conclusively shown that these workplace changes prevent the occurrence of carpal tunnel syndrome.
Symptoms of carpal tunnel syndrome may include:
- Numbness, tingling, burning, and pain — primarily in the thumb and index, middle, and ring fingers. This often wakes people up at night.
- Occasional shock-like sensations that radiate to the thumb and index, middle, and ring fingers
- Pain or tingling that may travel up the forearm toward the shoulder
- Weakness and clumsiness in the hand — this may make it difficult to perform fine movements such as buttoning your clothes
- Dropping things — due to weakness, numbness, or a loss of proprioception (awareness of where your hand is in space)
In most cases, the symptoms of carpal tunnel syndrome begin gradually, without a specific injury. Many patients find that their symptoms come and go at first. However, as the condition worsens, symptMessage Us
Your doctor may order electrophysiological testing of your nerves to measure how well your median nerve is working and help determine whether there is too much pressure on the nerve.
An ultrasound uses high-frequency sound waves to help create pictures of bone and tissue. Your doctor may recommend an ultrasound of your wrist to evaluate the median nerve for signs of compression.
X-rays provide images of dense structures, such as bone. If you have limited wrist motion or wrist pain, your doctor may order X-rays to exclude other causes for your symptoms, such as arthritis, ligament injury, or a fracture.
Magnetic resonance imaging (MRI) scans.
MRI scans provide better images of the body’s soft tissues than X-rays. Your doctor may order an MRI to help determine other causes for your symptoms or to look for abnormal tissues that could be impacting the median nerve. An MRI can also help your doctor determine if there are problems with the nerve itself, such as a tumor or scarring from an injury.
Carpal Tunnel Syndrome
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.
Carpal Tunnel Syndrome Treatment
Your treatment will depend on your symptoms and how far your condition has progressed. You might need:
- Lifestyle changes. If repetitive motion is causing your symptoms, take breaks more often or do a bit less of the activity that’s causing you pain.
- Exercises. Stretching or strengthening moves can make you feel better. Nerve gliding exercises can help the nerve move better within your carpal tunnel.
- Immobilization. Your doctor may tell you to wear a splint to keep your wrist from moving and to lessen pressure on your nerves. You may wear one at night to help get rid of that numbness or tingling feeling. This can help you sleep better and rest your median nerve.
- Medication. Your doctor may give you anti-inflammatory drugs or steroid shots to curb swelling.
- Surgery. If none of those treatments works, you might have an operation called carpal tunnel release that increases the size of the tunnel and eases the pressure on your nerve.
Living with Carpal Tunnel Syndrome
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.
What causes carpal tunnel syndrome (CTS)
CTS happens when the carpal tunnel inside your wrist swells and squeezes 1 of your nerves (median nerve).
You’re more at risk if you:
- are overweight
- are pregnant
- do work or hobbies that mean you repeatedly bend your wrist or grip hard, such as using vibrating tools
- have another illness, such as arthritis or diabetes
- have a parent, brother or sister with CTS
- have previously injured your wrist
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.