Carpal tunnel syndrome

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Carpal tunnel syndrome can cause pain and other symptoms in the hand. It is caused by pressure on a nerve around the wrist. Treatment is usually effective.

What is the carpal tunnel?

There are eight small bones called carpal bones in the wrist. A ligament (also called retinaculum) lies across the front of the wrist. Between this ligament and the carpal bones is a space called the carpal tunnel. The tendons that attach the forearm muscles to the fingers pass through the carpal tunnel. A main nerve to the hand (median nerve) also goes through this tunnel before dividing into smaller branches in the palm.

The median nerve gives feeling to the thumb, index and middle fingers, and half of the ring finger. It also controls the movement of the small muscles at the base of the thumb.

What is carpal tunnel syndrome?

This syndrome is a set of symptoms caused by compression (squashing) of the median nerve in the carpal tunnel. About 1 in 1000 people develop this syndrome each year. Most cases occur in people in their 40s and 50s, but it can occur at any age. It is also common during pregnancy. Women are affected 2-3 times more often than men.

What are the symptoms of carpal tunnel syndrome?

'Pins and needles'. This is tingling or burning in part, or all, of the shaded area shown above. The index and middle fingers are usually first to be affected.
Pain in the same fingers may then develop. The pain may travel up the forearm.
Numbness of the same finger(s), or in part of the palm, may develop if the condition becomes worse.
Dryness of the skin may develop in the same fingers.
Weakness of some muscles in the fingers and/or thumb occurs in severe cases. This may cause poor grip and eventually lead to muscle wasting at the base of the thumb.

Symptoms vary from mild to severe depending on how 'squashed' the median nerve becomes. One or both hands may be affected. Symptoms tend to come and go at first, often after you use the hand. Typically, symptoms are worse at night and may wake you up. The symptoms may be eased for a while by raising the hand up or hanging it down. 'Flicking' the wrist may also give relief. Symptoms persist all the time if the condition becomes severe.

What causes carpal tunnel syndrome?

Unknown. In most cases it is not clear why it occurs. It is thought that some inflammation develops in a tendon going through the carpal tunnel which causes swelling. There is little space to expand in the narrow tunnel, and this may lead to pressure on the nearby median nerve. Tendon inflammation can occur if you over-use your hand. Carpal tunnel syndrome is more common in manual workers, especially with jobs using a lot of wrist movement such as scrubbing or wringing.
Your genes may play a part. There seems to be some hereditary (genetic) factor. About 1 in 4 people with carpal tunnel syndrome have a close family member (father, mother, brother, sister) who also has or had the condition.
Bone or arthritic conditions of the wrist such as rheumatoid arthritis or wrist fractures may lead to carpal tunnel syndrome.
Various other conditions are associated with carpal tunnel syndrome. For example: pregnancy, obesity, an underactive thyroid, diabetes, the menopause, other rare diseases, and a side-effect of some drugs. Some of these conditions cause water retention (oedema) which may affect the wrist and cause carpal tunnel syndrome.
Rare causes include cysts, growths, and swellings coming from the tendons or blood vessels passing through the carpal tunnel.

Do I need any tests?

Often the symptoms are so typical that no tests are needed to confirm the diagnosis. If the diagnosis is not clear then a test to measure the speed of the nerve impulse through the carpal tunnel may be advised (nerve conduction test). A slow speed of impulse down the median nerve will usually confirm the diagnosis.

What are the treatment options for carpal tunnel syndrome?

General measures

Try not to over-use your wrist by excessive squeezing, gripping, wringing, etc. If you are overweight, losing some weight may help. Painkillers may be prescribed to ease the pain. If the condition is part of a more general medical condition (such as arthritis) then treatment of that condition may help.

Not treating may be an option

In up to 1 in 4 cases the symptoms go without treatment within a year or so. (In about 2 in 3 cases that develop during pregnancy the symptoms go after the baby is born.) So, not treating is an option, particularly if symptoms are mild. The situation can be reviewed if symptoms get worse. Symptoms are most likely to go in people less than 30 years old.

A wrist splint

A removable wrist splint (brace) is often advised as a first active treatment. The aim of the splint is to keep the wrist at a neutral angle without applying any force over the carpal tunnel so as to 'rest' the nerve. This may cure the problem if used for a few weeks. For example, in one research trial comparing splinting with surgery, about 1 in 3 patients treated with a splint were satisfied with the relief of symptoms it gave. A splint may be a bit cumbersome to use during the daytime. However, it is common to wear a splint just at night which is often sufficient to ease symptoms.

A steroid injection

Steroids reduce inflammation. An injection of steroid into, or near to, the carpal tunnel is an option. The steroid is combined with a local anaesthetic to make the injection less painful. One research trial found that a single steroid injection eased symptoms in about 3 in 4 cases. In this trial the symptoms returned in some people. However, about half of the treated people were free of symptoms a year later. Other studies report variable success rates with steroid injections.

Surgery

A small operation can cut the ligament over the front of the wrist and ease the pressure in the carpal tunnel. This usually cures the problem. It is usually done under local anaesthetic. You will not be able to use your hand for work for a few weeks after the operation. A small scar on the front of the wrist will remain. There is a small risk of complications from surgery. For example, following surgery there is a small risk of infection and damage to the nerve.

Other treatments

Over the years, a wide range of other treatments have been advocated. For example, diuretics (water tablets), exercises, vitamin B6, chiropractic manipulation of the wrist, yoga, magnet therapy, and treatment with ultrasound. None of these treatments has good research evidence to support their use and so are not commonly advised. Steroid tablets may ease symptoms in some cases. However, there is a risk of serious side-effects from taking a long course of steroid tablets. Also, a local injection of a steroid (described above) probably works better. Therefore, steroid tablets are not usually advised.

Which is the best treatment for me?

A non-surgical option may be advised if symptoms are mild. For example, if symptoms 'come and go' and mainly consist of tingling, pins and needles or mild discomfort. A splint may work but a steroid injection is probably the most effective non-surgical treatment.

If you try a non-surgical treatment and it does not work, do return to your doctor. In particular, if you have constant numbness in any part of your hand, or if you have any weakness of the muscles next to the thumb. These symptoms mean that the nerve is not working well and is at risk of permanent damage.

Surgery gives the best chance of long-term cure. It is quite a common operation. It is done if symptoms persist despite other treatments, or if symptoms are severe and the nerve is in danger of permanent damage.

Treatment for severe symptoms

If you have severe symptoms, in particular, wasting of the muscles at the base of the thumb, then you will probably need surgery. This is to decompress the trapped nerve quickly which aims to prevent any permanent long-term damage to the nerve.