Ignoring the signs of carpal tunnel syndrome can cause permanent damage to your hand.

The hand is a miracle of engineering, but it has one design flaw: the tendons that control the fingers pass through a narrow tube in the cleft of the hand called the carpal tunnel.

The median nerve that controls all the fingers except the pinky is also squeezed into that narrow tube, so any inflammation or swelling puts pressure on that vital nerve.

Carpal tunnel is the injury that causes the longest absences from the workplace, but doctors are still not entirely sure what causes it.

It is known that diseases like rheumatoid arthritis and diabetes increase the risk. Women are three times more likely than men to develop CTS, perhaps because their hands are smaller and therefore the carpal tunnel is narrower. Pregnancy increases the risk further.

High-impact, repetitive movements involving extreme flexion of the hand can lead to carpal tunnel. Workers in slaughterhouses who carve meat off the bones of animal carcasses were some of the first to develop this crippling condition.

Many people believe that low-impact repetitive movements like typing can also bring on carpal tunnel, but not all doctors agree.

Whatever the cause, the signs are clear: pain, numbness, or weakness, especially in the three larger fingers and the thumb, which are controlled by the median nerve.

The first line of treatment is to wear a simple wrist-brace at night. Ice may also help. If these don’t end the symptoms after a couple of weeks, a doctor might prescribe a shot of cortisone.

If none of these measures work, surgery is an option. About half a million people each year have a procedure to sever the band of tissue that holds the carpal tunnel closed. This relieves pressure on the median nerve.