Carpal Tunnel Syndrome (CTS) affects about one in a thousand people (mostly women) each year, and is caused by the median nerve being compressed as it runs through the carpal tunnel, a ligament that is located in the wrist. The tendons that control finger movement all run through the carpal tunnel, so when they become inflamed and swollen the amount of space is reduced, putting increased pressure on the median nerve.
In many cases, the cause of carpal tunnel syndrome is not clear. There are some theories as to why women tend to suffer from CTS more than men. One is that they have smaller wrist bones, and thus a smaller space through which the tendons can pass. Another is that, as it is more common during pregnancy and around menopause, hormonal shifts may be a causative factor.
Some people may have a genetic predisposition for CTS. Approximately one out of four people has a close family member who has also has the disorder. Trauma or an injury to the wrist may trigger CTS, such as a sprained or broken wrist. The vibration of power tools or heavy machinery, for instance a rotary sander, can sometimes trigger CTS.
Those who have jobs involving repetitive movements of the arm are more likely to contract carpal tunnel syndrome, such as workers on an assembly line, carpenters, violinists, etc. Interestingly, though long-term computer use was previously thought to contribute to CTS, there is now conflicting information about the relationship between keyboarding and CTS. Some studies, such as one from 2007 published in the journal Arthritis and Rheumatism, have found that those who use a keyboard intensively at work actually have a significantly lower risk of developing CTS.