What is 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 (median nerve) to the hand 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 causes carpal tunnel syndrome?

• You have an increased risk of carpal tunnel syndrome if a close family member (father, mother, brother, sister) also has or had the condition.
• Activities with repetitive hand/wrist movement, such as:
  • Gardening, assembly line work, and occupations requiring forceful or repetitive hand grip/exertion
  • Use of vibrating hand tools
  • There may be a link between carpal tunnel syndrome and using a computer, but the evidence for this is uncertain.
• Obesity
• Osteoarthritis of the joint at the base of the thumb (metacarpophalangeal joint). This is due to compression of the median nerve by bony lumps (osteophytes).
• Inflammatory joint disease, such as rheumatoid arthritis
• Ganglion cysts, tumour, scar tissue
• Hypothyroidism
• Diabetes mellitus.

What are the symptoms of carpal tunnel syndrome?

• Pins and needles. This is numbness and tingling in part or all of the shaded area (see diagram above). This is typically the first symptom to develop. 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 and even to the shoulder.
• 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 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 hand and wrist may also give relief. Symptoms persist all the time if the condition becomes severe.

Do I need any tests for carpal tunnel syndrome?

Often the symptoms are so typical that no tests are needed to confirm the diagnosis.

How do you treat carpal tunnel syndrome?

In up to one in three cases the symptoms go without treatment within six months or so. Symptoms are most likely to go in younger people.

In about two in three 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 become worse Therefore, a non-surgical treatment, such as a splint, is usually advised at first.

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. However, it is common to wear a splint just at night, which is often sufficient to ease symptoms

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 relieve pressure on (decompress) the trapped nerve quickly, which aims to prevent any permanent long-term nerve damage.

General care

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.

General advice

If symptoms are not beginning to improve after 72 hours, return to your local Minor Injury Unit, Urgent Treatment Centre or see your doctor.