Carpal tunnel syndrome is numbness, tingling and pain in the thumb and fingers of one or both hands. It is caused by pressure on the nerve that passes into the hand. Carpal tunnel syndrome is more common in women than in men. One survey found that it affects 7% of women, compared with 1% of men. The condition can occur at any age, but tends to affect those in their 40s and 50s.
The carpal tunnel is a narrow space at the front of your wrist. The tendons that bend the fingers and wrist pass through this space. A tough ligament, known as the retinaculum, covers the carpal tunnel and prevents the tendons pulling away from your wrist when it is bent.

The main nerve to your hand is called the median nerve, and also passes through the carpal tunnel, before dividing into smaller branches in your palm. Space in the carpal tunnel is limited, and there is no room for the tendons to expand. Therefore any swelling in the region will compress the median nerve and interfere with nerve impulses. This can cause pain, which may become prolonged and intense, making it difficult to grip things.

The main symptom of carpal tunnel syndrome is pain in your hand, and sometimes in your forearm. Symptoms can vary from mild to severe depending on how compressed the median nerve is. The symptoms are usually worse at night, but may also be noticed during daily activities, such as driving. Some people find that they drop things due to a weakened grip.
Specific symptoms of carpal tunnel syndrome include:

a weakened grip in the affected hand, often affecting your thumb. In some people, there may also be wasting of the muscles at the base of the thumb.
Causes
The symptoms of carpal tunnel syndrome are caused by compression (squashing) of the median nerve. However, exactly why it happens is unknown. If a tendon that passes through the narrow carpal tunnel becomes inflamed and swells, it may put pressure on the nearby median nerve.
Carpal tunnel syndrome may also be caused by the following:

Bone conditions in the wrist, such as rheumatoid arthritis, can cause thickening of the ligament that covers the carpal tunnel.
Wrist injuries, such as joint dislocations and fractures, can narrow the carpal tunnel and put pressure on the median nerve.

Hormonal changes, such as an under-active thyroid gland (hypothyroidism) or an over-active thyroid gland (hyperthyroidism). Taking the combined oral contraceptive pill, and the menopause, can also disrupt the hormone balance and lead to carpal tunnel syndrome.
Other conditions, such as pregnancy, obesity and diabetes mellitus are sometimes associated with carpal tunnel syndrome. Some of these conditions can cause water retention (oedema) which can lead to swelling in the wrist.
Rare conditions, such as cysts growths, or swellings of the tendons or blood vessels that pass through the carpal tunnel.

Carpal tunnel syndrome can often be diagnosed from an examination and description of your symptoms. Other disorders of the median nerve have similar symptoms, but carpal tunnel syndrome is the most common cause.
Your GP may tap the inside of your wrist to see if this causes pins and needles, or a shock sensation to your fingertips. This is known as Tinnel’s sign, and it may show that the median nerve is not working properly.

may be used to assess how well your nerve is conducting electrical signals. The nerve is stimulated using an electrical impulse, and its response time to the impulse is measured.

A muscle test, called an EMG (electromyography), may also be carried out to check whether a muscle disorder is causing the problem. A fine needle is used to measure the electrical activity of your muscle when resting and when tense. The needle is placed in or on the muscle, and the results are displayed on a computer screen.

Occasionally, a blood test is necessary to rule out a problem with the thyroid gland
Treatment
There are a number of different treatment options for carpal tunnel syndrome. Resting your wrist by not squeezing, or gripping, may help to relieve your symptoms. Losing weight (if you are overweight) will help too. If you have a medical condition, such as arthritis, then treating it may also help.
More specific treatments for carpal tunnel syndrome include:
Wrist splints, to keep your wrists in a position that maximises room in the carpal tunnel. They are usually worn at night, but some people need to wear them during the day as well. Your GP or physiotherapist may be able to provide you with wrist splints.
Non-steroidal or anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen can be used to reduce inflammation and relieve pain. However, children under the age of 16 should not take aspirin, unless their GP specifically advises them to do so. Those with asthma should not take ibubrofen.

will reduce inflammation and help to ease your symptoms. They are available on prescription, but are not always suitable for people with diabetes. They are taken orally (by mouth) or they are injected directly into the wrist. However, long-term steroid use is not recommended because side-effects can develop.
Diuretic tablets will help you to pass urine, and can reduce swelling caused by fluid retention in your body’s tissues.
Ultrasound treatment can relieve symptoms in some people. How it works is not fully understood but it is thought to relieve inflammation. It is painless and requires a minimum of 20 treatments. However, this type of treatment may not be available in all areas.
Wrist and finger exercises may help to relieve the pressure on the median nerve. However, there has not been enough research to tell whether such exercises are effective, and there is a risk that they could make the condition worse. You should ask you GP or physiotherapist for advice.
Surgery may be required if the symptoms of carpal tunnel syndrome persist, or are severe. A simple operation, under local anaesthetic, is performed, which involves the ligament being cut to release the pressure on the median nerve. Surgery relieves pain in about nine out of 10 people who have it.

In cases of carpal tunnel syndrome where the symptoms are mild, no treatment may be an option. In one in three cases, the symptoms disappear within six months, without treatment. Where the condition develops during pregnancy, the symptoms usually disappear soon after the baby is born.

Carpal tunnel syndrome can be difficult to prevent because it often occurs following a wrist injury, or a bone condition, such as rheumatoid arthritis. If you have rheumatoid arthritis, receiving treatment for the condition will help. A specialist rheumatologist will prescribe an anti-rheumatic medicine to slow down the disease and prevent joint damage.
Even though there has not been any clinical evidence to suggest that tasks involving repetitive use of the wrists and hands causes carpal tunnel syndrome, it is important to adopt good working practices. For example, when using a computer for prolonged periods, you should ensure that your workstation is set up correctly, and that you maintain a good posture. You may find that using a wrist rest helps, and you should also take regular screen breaks.
If you are overweight, adjusting your diet and losing a reasonable amount of weight will help to alleviate the symptoms of carpal tunnel syndrome, and prevent the condition from occurring in future. Your GP will be able to provide you with help and advice about diet and weight loss.