Causes of carpal tunnel syndrom

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

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You might have omitted the "e" at the end of syndrome during your search, but no matter...Carpal tunnel syndrome is a common condition that occurs when there is too much pressure on the median nerve in the wrist. There is usually aching, numbness or tingling in the thumb, some of the fingers and sometimes part of the hand.

Carpal tunnel syndrome affects about 1 in 100 people at some point in their life. Men and women of any age can develop it. It is most common in women in their fourth to sixth decades.

Sometimes carpal tunnel syndrome is triggered by a person’s occupation, and can lead to the person being unable to work. Most cases of carpal tunnel syndrome can be prevented by stopping or reducing the activity that stresses the fingers, hand, or wrist, or by changing the way in which activities are done.

The carpal tunnel is a channel in the palm side of the wrist. The bones of the wrist are arranged in a semi-circle, and a tough ligament (the carpal ligament) forms a roof over them, creating a passageway (the carpal tunnel). Running through the carpal tunnel are the tendons that are used to bend the fingers and wrist, and the median nerve. This is one of two nerves that allow feeling in the hand. The median nerve also controls some of the muscles that move the thumb.

There is little room for expansion in the tunnel, so any swelling of the tissue in or around the carpal tunnel can press on the median nerve and cause the symptoms of carpal tunnel syndrome.

Carpal tunnel syndrome may result from the tunnel walls being compressed, putting pressure on the nerve. Repeated wrist movements can also be responsible for this. The movements may be related to a person’s job or hobby, such as typing, knitting or using small tools. People who use vibrating tools are particularly at risk.

The condition is more likely to develop if the wrist has been injured, after it has been broken, for example. The carpal tunnel may also be compressed through rheumatoid arthritis, or in a condition where excess growth hormone is produced. This condition is called acromegaly.

Another cause of carpal tunnel syndrome can be pressure within the tunnel, often due to fluid retention as a result of kidney failure, an underactive thyroid or during pregnancy. It can be caused by changes to the median nerve itself, too, which may happen with conditions such as diabetes.

Carpal tunnel syndrome is more common in people who are very overweight, in women who are pregnant or taking the contraceptive pill, and during the menopause. In some people, it develops for no apparent reason.

Symptoms include aching, tingling, pins and needles, burning, numbness or pain in the hand and in the digits served by the median nerve – the thumb, the index and middle fingers, and part of the ring finger. In time, symptoms can spread to the arm and shoulder.

These symptoms tend to be worse at night or first thing in the morning and are often made worse by strenuous wrist movements.

Carpal tunnel syndrome can affect one or both hands, and the severity of the symptoms can vary. The symptoms may be mild or only occur from time to time. As the condition worsens, symptoms may become constant. The hand muscles may become weakened, making it difficult to grip objects, and there may be permanent loss of feeling. Fine finger movements, such as writing, may become more difficult.

Treatment aims to relieve the symptoms of carpal tunnel syndrome by reducing the pressure on the median nerve.

People often find temporary relief from symptoms by hanging their arm out of the bed at night or by shaking their hand vigorously with a flicking action. Mild symptoms may also be relieved by applying ice packs to the wrist (ice should not be applied directly to the skin), and by resting the hands and wrists regularly. Wrist splints can be used, either at night, or both day and night. These help to keep the wrist straight and avoid putting more pressure on the compressed nerve.

If the condition is linked to the way the hands are used, it is important to try and avoid the repetitive actions that cause the symptoms. Changing the way repetitive movements are done, reducing the frequency of the actions, and increasing the amount of rest between periods of activity should help.

Stretching exercises may help relieve symptoms and also keep the area mobile, maintaining blood flow to the muscles in the hand and arm.

Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can reduce swelling, and so relieve pain. However, there is little scientific evidence to suggest that these are effective for carpal tunnel syndrome. There are possible side-effects including gastrointestinal upset such as nausea, stomach pain, and stomach ulcers.

There are other medicines available that may help reduce the symptoms of carpal tunnel syndrome. These need to be prescribed by a doctor.

• Corticosteroid tablets (eg prednisolone). These may provide some short term relief.
• Steroid injections (eg hydrocortisone). These are given into the carpal tunnel to reduce swelling and give temporary relief from symptoms.
• Prescription-only NSAIDs, such as diclofenac (eg Voltaren) and celecoxib (Celebrex) may help.
• If excess fluid is thought to be causing the swelling, a doctor may prescribe a diuretic drug that causes the body to excrete more water in the urine. However, there is little scientific evidence to suggest diuretics are effective at relieving symptoms.
• Vitamin B6 (pyridoxine) may be helpful in some cases.


Some people find that massage or acupuncture helps reduce pain.

If the symptoms get worse, and the cause of the carpal tunnel syndrome can’t be removed, the only effective long-term treatment is surgery. The operation (carpal tunnel release) involves cutting the carpal ligament to make more space for the nerves and tendons in the carpal tunnel. It can usually be done as day case surgery. The operation may be done using an endoscope, a thin flexible telescope that is inserted into a small cut in the wrist. Images are transmitted to a screen, allowing the surgeon to see inside the wrist. In a more traditional, open operation, a longer cut is made in the palm of the hand. The endoscopic repair leaves a smaller scar, and usually allows people to get back to their usual activities more quickly. However, there may be a slightly higher risk of nerve damage with the endoscopic repair.

Carpal tunnel surgery, per se, may be a thing of the past. Here’s why…

A much newer and much less invasive technique that has excellent results is percutaneous ultrasound guided release. In this technique, a small needle is inserted using local anesthetic. Using ultrasound guidance, multiple small holes are made in the flexor retinaculum (the tough fibrous roof over the carpal tunnel that compresses the median nerve). At the same time, fluid is injected into the retinaculum to spread and weaken the fibers. At the end of the procedure, the wrist is flexed (bent) and the weakened retinaculum is released. A splint is applied and the patient has full use of their hand by the next day.

Carpal tunnel syndrome doesn’t follow a predictable course. In around one in three people with the syndrome, the condition gets better without any treatment.

Some people have symptoms that get progressively worse, while others only have symptoms from time to time. If treated early, mild cases usually get better without surgery.

Improvement may occur once any underlying cause is removed, for example, after the end of a pregnancy, or when any underlying condition, such as diabetes or an underactive thyroid, is treated.

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