Aging Begins at 30

Tingling at the Wrist and Beyond

The transverse carpal (Karpos is a wrist in Greek) ligament keeps the tendons of the long bending muscles of the fingers and the median nerve from breaking free from the wrist bones. The tunnel formed by the wrist and ligament can trap the tendons and pinch the nerve, especially if there is any swelling of the tendons from inflammation or fluid retention. Repetitive wrist movement from driving, typing, sewing, knitting or carpentry work will cause the syndrome. Workers in certain jobs such as meat, fish and poultry processing, construction trades, electronics assembly, vibrating tool users, logging and sawmill operation, supermarket cashiering and scanning, hairdressing, some factory and farm workers are likely to get carpal tunnel syndrome. Premenstrual or pregnancy swelling or low thyroid hormone can also cause it. Rarely it is associated with rheumatoid arthritis or gout. It is most common in middle-aged women.

There is an estimated lifetime risk of 10% and an annual risk of 0.1% among adults. There has been a substantial increase in work-related cases in the 1980s and early 1990s. In the general population about 0.6% of men and 5.8% of women have the syndrome. Direct medical costs are more than $1 billion per year.

When you examine someone with this problem there is wasting of the thumb half of the ball of muscle at the base of the thumb. There is increased sensitivity to pin prick in the distribution of the median nerve (the three and a half fingers on the thumb side). Light tapping of the tendons above tunnel will cause tingling. If the hand is bent downwards as far as it will go for a minute symptoms will return and will be relieved when the wrist is straightened. An exaggerated prayer position of the hands will also bring on the symptoms.

When the symptoms are minor a wrist splint worn mainly at night or anti-inflammatory drugs such as aspirin and avoidance of the causative movements may be all that is needed. Injection of steroids into the wrist to reduce inflammation may help. Failure to eliminate contributing job factors can result in recurrence or progression. About 90% of people who are mildly affected recover fully with this treatment. If the symptoms persist or there is muscle weakness, a surgical decompression of the tunnel with removal of any inflammatory tissue is needed.

Damage from repeated movement of a part of the body when physical routine is unvaried is now categorized as Repetitive Stress Injury (RSI). According to the National Academy of Sciences this is now costing the nation $20 billion annually. To avoid the high cost of RSI some businesses have introduced ergonomic (muscle efficiency) workstations and alternating types of work, and enforced rest periods. A similar kind of compression damage to a nerve can be produced by the pressure of an arm against the armrest of a wheelchair or when crossed legs put pressure on the nerve that crosses bone at the outside of the knee, causing foot drop.

Section Top | Title Page

See related Patient Topics Bones, Joints and Muscles, Brain and Nervous System, Carpal Tunnel Syndrome, Ergonomics, Safety or Wellness and Lifestyle.

See related Provider Topics Bones, Joints and Muscles, Brain and Nervous System, Ergonomics, Safety or Wellness and Lifestyle.

All contents copyright © 1992-2004 the Author(s) and The University of Iowa. All rights reserved.

http://www.vh.org/adult/patient/internalmedicine/aba30/2001/carpaltunnelsyndrome.html