With so many people earning their living at computer keyboards, it’s no wonder there’s been so much discussion lately about carpal tunnel syndrome (CTS). But it’s not just wordsmiths who are at risk for developing this painful affliction of the hand and wrist. Any repetitive hand or wrist motion can lead to CTS, and nail technicians, who sculpt, file, and buff nails all day, need to be especially scrupulous about correct posture and hand positions to avoid developing this debilitating, career-threatening injury.

But before we can prevent CTS, we need to understand its actual cause-anatomically speaking, that is. How do we bend our wrist and move our hand?

Let’s say you’re about to file someone’s nails. First, a nerve impulse travels from your brain down your spinal cord at high speed, then races through your arm to the median nerve. This is the large nerve that connects directly with most of the muscles that bend your wrist and close your fist. These muscles then contract, pulling on a tendon (which is the part of the muscle that attaches to the bone). When the tendon is pulled, the hand bends at the wrist joint and the fingers bend inward. Nerve impulses returning to the brain tell it that your wrist is bent and how much, how hard you’re gripping with your hand, and what the object you’re gripping feels like.

Now you know what body parts moving your hand involves-the nerves, muscles, tendons, and bones. Now hold out your hand and open it with the palm up. At the base of your hand are eight carpal bones that, along with the ends of the two forearm bones, form the wrist. The carpal bones are held together by though, fibrous tissues called ligaments. These ligaments run perpendicular to your fingers and are positioned over the median nerve and hand muscle tendons. In other words, the median nerve and the tendons sit inside a “sandwich,” with bone on the bottom and ligaments on top. This sandwich is called the carpal tunnel.

Perhaps you can visualize now why repetitive wrist bending or finger flexing can overtax the tendons that operate within the narrow space of the tunnel. Just bending the wrist normally compresses the tunnel contents. With overuse, the sheath around these tendons can become inflamed, or the tendons themselves can swell. This swelling takes up more of the valuable space in the carpal tunnel, thus putting pressure on the median nerve. Pressure on this nerve can result in pain, of course, but also in muscle weakness, since there is a decrease in the impulses that can get through that nerve to the muscle in the numbness, tingling, and other abnormal sensations, referred to as parasthesias.

If you start to feel numbness, tingling, and other abnormal sensations in your hand, they could be the first warning signs that you are developing CTS.

To prevent the ailment from worsening (and hopefully before it gets this far), you must learn to use good posture and hand and body mechanics while working. Remember, posture and body, since everything is connected. Modify your work habits and work area before they modify you.

If you work sitting, you should be in a comfortable position with your back straight (not hunched). If necessary, the chair should have armrests. Make sure that when using your hands they are in the most comfortable position in relation to the position of your body. Observe how you perform a fill: are you bending your wrists while applying product or filing? Try to find a position that keeps your wrists straight as you do these tasks. If you have no choice but to perform the same or similar tasks in succession, take frequent breaks to massage and flex your hands.

After work each day, take a little time to massage and ice your hands. First, rub some lotion into your hands, putting extra pressure on the sorest area. This will increase the circulation-and the inflammation. Then, fill a sealable plastic bag with crushed ice and hold it on your wrists for 15-20 minutes. If you’re on the run, massage your hand and wrist with an ice cube until they are numb.

Another form of treatment is to use a wrist splint. Wrist splints are a way of keeping the wrist and hand in a neutral (non-bending) position to avoid compression in the tunnel. The splint offers temporary relief and is a useful tool for people who overuse their hands. There’s surgery, of course, if all else fails to alleviate the pain. But there is no reason for CTS to get to that point. With a few adjustments in work habits and a little time each day spent taking care of your own hands, you’ll see the light at the end of the carpal tunnel, I guarantee it.

By Marc Levine, a registered physical therapist and president of Ther Ex Inc., a physical therapy company that provides home health care in Los Angeles.