Carpal Tunnel Syndrome

Written by Dr Richard Lawson FRACS - Hand Surgeon

What is the carpal tunnel?

The carpal tunnel is a small space at front of the wrist joint, under the heel of the hand, that is bounded by the small bones of the wrist and a tough ligament called the transverse carpal ligament. It contains a number of structures, including the median nerve, and nine tendons that flex the fingers and thumb. The nerve and tendons need to pass through the carpal tunnel to get from the forearm into the hand.

What is carpal tunnel syndrome?

A condition where the space available for the median nerve and flexor tendons is insufficient, resulting in compression of the nerve and tendons. While the excess pressure on the tendons has little apparent ill effect, the pressure on the median nerve leads to the symptoms of carpal tunnel syndrome.

These generally start with numbness and tingling in the hand, typically more on the thumb side of the hand than the little finger side. These often become first apparent at night, but as the disease progresses the numbness and tingling can occur during the day as well, and may become constant.

Other features of carpal tunnel syndrome include pain in the hand that may extend into the forearm, clumsiness when using the hand, and in more advanced cases wasting of the muscles of the ball of the thumb.

Who gets carpal tunnel syndrome and how common is it?

Carpal tunnel syndrome is very common, and operations to treat the condition are amongst the commonest operations that hand surgeons perform. Carpal tunnel syndrome tends to be seen in patients of middle age and older, although it is also frequently seen in pregnant women, and as a whole is more common in women than men.

Carpal tunnel syndrome is seen more frequently in patients with rheumatoid arthritis and diabetes, but most patients with the syndrome have neither of these conditions.

How is carpal tunnel syndrome diagnosed?

The main complaints of the patient and a careful physical examination are the most important components of making a diagnosis, but sometimes extra tests are required. These may include an X-ray of the wrist, particularly if there has been a history of a fracture or other trauma to the wrist, and nerve conduction studies, which look at the electrical qualities of the median nerve; as nerve damage progresses the performance of the nerve decreases on nerve conduction studies.

How is carpal tunnel syndrome treated?

Treatment often starts with simple measures such as changing work practices or posture, use of a splint at night to prevent the wrist flexing excessively, and sometimes an injection of cortisone into the carpal tunnel to decrease swelling within the carpal tunnel.

Surgical treatment consists of dividing the transverse carpal ligament, thereby releasing the pressure on the nerve. This is done via an incision in the palm, just past the wrist crease, which extends for several centimetres towards the fingers.

What happens after the operation?

After the operation the scar is dressed and the hand bandaged.

It is very important to start moving the fingers as soon as possible after the operation, to prevent the median nerve sticking to the surrounding tendons.

The stitches are usually removed around 12-14 days after the operation, and at this time it is important to start massaging the scar with some sorbolene cream; this will make the scar softer and more supple. This should continue for a minimum of three months after surgery.

It usually takes 4-6 weeks before the tenderness in the scar subsides enough to start using the hand for heavier work, but you are encouraged to start using the hand for light day to day activities such as working on the computer or using a knife and fork as soon as pain permits.

You can start driving when it is comfortable (around 5-7 days).

You should take a vitamin C tablet every day, as this has been shown to decrease the chance of having ongoing pain and stiffness in the hand.

What kind of results can I expect?

The operation is usually very successful in treating pain. It should also prevent any numbness getting worse, and in cases of moderate or mild numbness, much or all of the numbness often gradually gets better. Wasting of the muscles of the ball of the thumb does not usually improve, and patients with constant numbness prior to the surgery may find that not all of the numbness resolves.

What are the possible complications of surgery?

Complications are uncommon, but can include problems with the anaesthetic, infection of the wound, failure to improve numbness, and very rarely, damage to the contents of the carpal tunnel. Tenderness around the wound lasting for some time after surgery is usually the most common complaint. This tenderness is seen in almost everybody and can last for weeks or even months but almost always settles down. Occasionally the hand can become quite painful and swollen, a condition known as RSD.