It often begins as an easily dismissed tingle in the thumb or an ache in the wrist. Building slowly but persistently to a searing, tearing pain from the wrist to the fingers. Culminating in sleepless nights, workless days and a numb but simultaneously excruciating, useless hand. Carpal tunnel syndrome is a painful and disabling condition. It’s also very common.
The carpal tunnel itself is a tunnel in the wrist made up of bony structures that are the base and walls, with a roof constructed by a dense fibrous sheet called the flexor retinaculum.
Through this tunnel courses a bundle of nerves, blood vessels and tendons that are the cables of supply to the hand. The syndrome is a result of pressure on the all important median nerve that travels through this space-limited tunnel.
The median nerve supplies sensation and strength to most of the thumb, several fingers and part of the palm. It is thought increased swelling or fluid in the carpal tunnel places pressure on this nerve resulting in the distressing symptoms experienced. Swelling may occur for several reasons, for example with repetitive hand movements or in pregnancy.
Who’s at risk?
Carpal tunnel syndrome has been reported to account for more days off work than any other occupation-related injury. Some 7.8% of the US working population are estimated to be affected and a UK study estimated an annual incidence of 120 per 100,000 women and 60 per 100,000 men.
An audit performed in general practice in Australia found there are about 195,000 appointments annually with patients for carpal tunnel syndrome.
It seems to occur more commonly in women, particularly during pregnancy. Although the mechanism is unclear, it is thought a combination of hormonal factors as well as increased fluid in the body of a pregnant woman increases the pressure in the carpal tunnel.