Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a relatively common condition that causes pain, numbness, and a burning, or tingling, sensation in your hand and fingers.

Symptoms of CTS can range from mild to severe.

The carpal tunnel

The carpal tunnel is a small tunnel that runs from the bottom of your wrist to your lower palm.

Several tendons pass through the carpal tunnel, which help to move your fingers. The median nerve also passes through the tunnel and this controls sensation and movement of your hand.

The nerve and tendons are protected by a ridge of bone and ligaments. In cases of CTS, the space inside the tunnel shrinks, placing pressure on the median nerve. Compression of the nerve results in symptoms of pain and numbness.

How common is CTS?

CTS is one of the most common conditions affecting the nerves of the hand. It is estimated that almost 5% of women and 3% of men have CTS. Most cases of CTS develop in people who are between 45-64 years of age.

CTS is also common in pregnant women. This may be due to the fluid retention that often occurs during pregnancy placing additional pressure on the carpal tunnel.

Prognosis

The likely prognosis of CTS seems to depend on the severity of symptoms.

People with mild to moderate symptoms usually respond well to non-surgical treatment, such as wrist splints and corticosteroids injections. However, more severe cases usually require surgery to reduce the pressure on the median nerve.

Cases of CTS that occur during pregnancy usually resolve after the birth.

Left untreated, CTS may lead to permanent nerve damage.

The main symptoms of carpal tunnel syndrome (CTS) are tingling, numbness, or pain in the median nerve which affects:

• the thumb,
• index finger,
• the middle finger, and
• half of the ring finger.

The symptoms of CTS are often worse at night and they may cause you to wake up.

Dexterity problems

If you have CTS, you may find that your hand becomes weak and clumsy and that you find it difficult to grip objects with your thumb.

Similarly, you may have problems using the affected fingers to carry out tasks that require high levels of manual dexterity, such as typing.

Keeping your hand, or wrist, in one position, or carrying out repetitive tasks, can make the symptoms of CTS worse. However, moving your hand, or shaking your wrist, can often help to relieve the symptoms.

In rare cases, you may also experience dry skin, swelling, or changes to the colour of your skin in the affected hand.

The symptoms of carpal tunnel syndrome (CTS) are caused by compression of the median nerve. The median nerve has two main functions:

• it relays physical sensations, such as your sense of touch, from your hand to your brain, and
• it relays nerve signals from your brain to your hand, allowing you to move your hand and fingers.

The compression of the median nerve can disrupt these nerve signals, which means that both your sense of touch and your ability to move your hand can be affected.

Compression of the median nerve can occur when the tendons that run through the carpal tunnel become inflamed and swollen.

Risk factors for carpal tunnel syndrome

The exact reason why changes to the structure of the carpal tunnel occur in some people is unknown, but a number of risk factors for CTS have been identified. These are outlined below.

Family history

CTS seems to run in families. About 25% of people with the condition have a close relative who also has CTS. Exactly how and why the condition is spread through families is not fully understood.

Health conditions

Certain health conditions appear to increase the risk of a person developing CTS. These include:

• rheumatoid arthritis,
• diabetes,
• gout,
• lupus (a condition where the immune system attacks healthy tissue),
• under-active thyroid gland (hypothyroidism),
• obesity; particularly in young people,
• damage, or fracture, to the wrist,
• pregnancy,
• oedema (excess fluid in the body's tissue),
• heart failure, and
• Lyme disease (a bacterial infection that is caused by ticks).

Less commonly, CTS occurs when a person has an abnormal wrist structure, such as an unusually narrow carpal tunnel, or as a result of cysts, growths, or swellings of the tendons, or blood vessels, that pass through the carpal tunnel.

Carpal tunnel syndrome (CTS) can usually be diagnosed by your GP who will examine your hand and wrist, and ask you about your symptoms

Physical tests

A common test that is used to help diagnose CTS involves tapping your wrist lightly to see if it produces a tingling feeling, or numbness, in your affected hand.

Another test involves you flexing your wrist for 60 seconds to see if this produces pain, numbness, or tingling in your affected hand.

A positive result for both tests would usually indicate that your median nerve is being compressed.

Further testing

Further testing is usually only required if your GP is uncertain about the diagnosis and wishes to rule out other conditions with similar symptoms, such as cervical neuropathy (a condition where a nerve ending gets pinched, or trapped, by the spine).

Further tests that may be used are outlined below.

Electromyography

Electromyography uses electrodes to measure the electrical activity of your muscles. This test can be used to see if any muscle damage has occurred.

Nerve conduction study

A nerve conduction study is a test that is similar to electromyography, except the electrodes are used to study how signals are transmitted through your nerves. A slowing of the signals can suggest nerve compression, or damage.

If it is thought that your CTS is due to an underlying health condition, such as rheumatoid arthritis, treating that health condition should also help to improve the symptoms of CTS.

Wrist splints

Wearing a wrist splint at night should help to reduce the compression on your median nerve, and help to improve your symptoms. However, it may take up to eight weeks for you to fully notice the benefits.

Wrist splints are usually available from the larger pharmacies, or your GP may be able to recommend a suitable supplier.

If you have CTS, you should try to minimize any activities that make your symptoms worse.

There is little evidence that ergonomic devices that are designed to be used when working with a keyboard, such as a wrist rest, are effective in treating the symptoms of CTS.

Corticosteroids

If your symptoms of CTS do not improve after three months, or they get worse, you may require additional treatment with corticosteroids.

Corticosteroids will help to reduce tendon inflammation, and can help to reduce the pressure on your median nerve. One injection of corticosteroids usually provides significant relief from the symptoms of CTS.

Surgery

Surgery is usually only recommended for severe cases of CTS, or if all other treatment options have failed. During surgery, the surgeon will cut some of the ligament that surrounds the carpal tunnel in order to reduce the pressure on the nerve.

There are two ways that carpal tunnel surgery can be carried out:

• open surgery - where the surgeon cuts through your wrist to release the nerve, and
• endoscopic surgery - where the surgeon makes a smaller incision in your palm, and uses a machine called an endoscope to release the nerve.

Endoscopic surgery tends to have a slightly faster recovery time, but apart from that there seems to be no real differences in terms of success between the two approaches.

In most cases of CTS, surgery can provide a complete and lasting cure. In a survey of 4,000 NHS patients who had surgery, 75% thought that the surgery had been entirely successful. However, as with any form of surgery, there is always a small risk of complications.

Reported complications include:

• infection,
• post-operative bleeding,
• nerve injury,
• persistent wrist pain, and
• the return of CTS symptoms.

Carpal tunnel syndrome (CTS) 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 may 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 working with computers causes CTS, 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 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 CTS, and prevent the condition from occurring in future.

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CKS Guidelines (2008) Carpal Tunnel Syndrome

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