Carpal tunnel syndrome

Carpal tunnel syndrome is a a disorder where the median nerve is compressed at the wrist, this causes tingling and weakness at parts of the hand. It is commonly caused by strain placed on the hand, for instance gripping and typing, which are usually performed repetitively in a persons occupation.

The median nerve runs through the carpal tunnel[?], a canal in the wrist that is surrounded by bone on three sides, and a fibrous sheath (the flexor retinaculum) on the other. As well as the nerve, many of the hand's tendons pass through this canal. The median nerve can be compressed by swelling of the contents of the canal, or by direct pressure from part of a broken or dislocated bone.

Carpal tunnel syndrome, due to RSI results because the narrowed tunnel of bones and ligaments in the wrist pinches the nerves, especially the median nerve and, to a lesser extent, the ulnar nerve. The first symptoms usually appear at night. Symptoms range from a burning, tingling numbness in the fingers, especially the thumb and the index and middle fingers, to difficulty gripping or making a fist, to dropping things. Some cases of carpal tunnel syndrome are due to work-related cumulative trauma of the wrist. This syndrome is much more common in women than it is in men.

There are a number of causes of carpal tunnel syndrome. They can be either traumatic, or non-traumatic.

Traumatic causes include:

• Fractures of one of the arm bones, particularly a Colles fracture[?].
• Dislocation[?] of one of the carpal bones of the wrist.
• Hematoma[?] forming inside the wrist, because of internal haemorrhaging.
• Deformities due to abnormal healing of old bone fractures.

Non-traumatic causes, generally happen over a period of time, and are not triggered by one certain event. Examples include:

• Tenosynovitis, which is inflammation of the joint. Part of the process of inflammation is swelling, and this compresses the nerve.
• With pregnancy and hypothyroidism, fluid is retained in tissues, which swells the joint.
• Acromegaly a disorder of growth hormones, compresses the nerve by the abnormal growth of bones around the hand and wrist.
• Tumours (though not necessarily cancer), such as a ganglion or a lipoma[?], can protrude into the carpal tunnel, reducing the amount of space.
• Diabetes, rheumatoid arthritis and obesity tend to cause swelling, thus decreasing the amount of space in the carpal tunnel.
• Idiopathic[?] causes, which no-one can explain, can also cause this disease.

If a specific action or movement (such as typing on a keyboard, or gripping a hammer) is bringing on carpal tunnel syndrome, then this action should be avoided. Unfortunately it may be a necessary part of that person's job, and treatment is necessary.

Carpal tunnel syndrome is treated by immobilizing the wrist in a splint to minimize or prevent pressure on the nerves. If that fails, patients are sometimes given anti-inflammatory drugs or injections of cortisone in the wrist to reduce the swelling.

There is also a surgical procedure in which doctors can open the wrist and cut the ligament (the flexor retinaculum[?]) at the bottom of the wrist to relieve the pressure. However, only a small percentage of patients require surgery. The surgery itself is very brief, and only a local anaesthetic is needed. Full recovery however, can take up to three months. This surgery can also be done endoscopically[?].

Approximately 1 percent of individuals with carpal tunnel syndrome develop permanent injury. The majority recover completely and can avoid reinjury by changing the way they do repetitive movements, the frequency with which they do the movements, and the amount of time they rest between periods when they perform the movements.

From http://www.ninds.nih.gov/health_and_medical/disorders/carpal_doc.htm