Carpal Tunnel Syndrome

By Deepi Brar, M.S.

You're working away on your computer, but lately you've been plagued by numbness and tingling in your fingers and wrist. You've felt more than an occasional sharp pain, and more puzzling, you've been waking up at night with a "pins and needles" sensation in one hand. There might be other explanations, but the symptoms suggest you may have carpal tunnel syndrome.

What causes carpal tunnel syndrome?

Carpal tunnel syndrome -- a common and painful disorder -- is a type of repetitive stress or overuse injury that's associated with repeated movements of the hand and wrist. Many other physical conditions may cause or contribute to it as well, including pregnancy, obesity, diabetes, and certain autoimmune diseases.

In the arm and hand, the blood vessels, nerves, and tendons that serve your fingers need to pass through a narrow tunnel formed by bones and ligaments in your wrist (the carpal tunnel). If the tendons in and around the tunnel get swollen, they may pinch the median nerve, the major nerve passing through the carpal tunnel. (One hand surgeon has compared the condition to three men in overcoats trying to rush through one door at the same time.)That can cause pain, numbness, weakness, and other problems.

Doctors don't fully understand what produces this swelling or pressure, but it appears that people with a small carpal tunnel are more prone to the disorder. The condition is especially common among assembly line workers. In fact, carpal tunnel syndrome is three times more common among assembly line workers than among data entry clerks. Posture also may play a role. Studies show that arching your wrist, bending your wrist repeatedly, or extending your arm outward from your body increases the pressure in the carpal tunnel. Forceful twisting motions (the kind you make when you turn a screwdriver, for example) or vibration (as when you use a power tool or grip bicycle handlebars for long stretches of time) can also aggravate the tendons and ligaments in your hands and wrists.

Women are three times more likely than men to develop carpal tunnel syndrome, possibly because they have smaller carpal tunnels to begin with; the hormonal changes that occur during menstrual cycles, pregnancy, and menopause can also make their hands (including the wrist ligaments) more prone to swelling. Overweight and inactive people are particularly likely to get carpal tunnel syndrome, as are people with endocrine disorders (like diabetes and hypothyroidism) or immune disorders (like arthritis and lupus). Many researchers believe that people with such conditions develop the syndrome more readily if they also overuse their hands and wrists.

What are the symptoms?

You may have carpal tunnel syndrome if you have one or more of these symptoms:

  • Pain, aching, stiffness, numbness, a "pins and needles" sensation, tingling, or a burning sensation in your hands or wrists, especially in the thumb and the index and middle fingers (occasionally the forearm is affected as well). The symptoms usually appear for at least a week or may flare up intermittently for more than a month.
  • Pain in your hands or forearms that often gets worse at night or after you use your hands.
  • Weakness and a loss of control in your hands and fingers, so that it's hard to grip and manipulate things.

Do I need to see a doctor?

You should see a doctor right away if you experience symptoms of carpal tunnel syndrome, and again if your symptoms start interfering with your normal activities. It's also a good idea to make sure you don't have a more serious condition that can cause similar symptoms. Left untreated, carpal tunnel syndrome can lead to constant pain and to permanent nerve and muscle damage that could severely limit your ability to use your hands. Fortunately, treatments are available, especially if you catch the condition early.

Doctors have lots of ways to find out what's happening in your hands and wrists. Several simple tests, for instance, can confirm pain or prickling sensations in the hand. Nerve conduction studies (or electrodiagnostic tests) are a more sophisticated gauge because they can pinpoint compression of or damage to the median nerve by measuring how fast electrical impulses move through it. (Up to 10 percent of people with carpal tunnel syndrome, however, test normal when this method is used.)

Magnetic resonance imaging (MRI) can give visual confirmation of a median nerve that's being compressed inside the carpal tunnel. These tests are only occasionally helpful and because of their high cost, they're rarely used. Your doctor may order several different tests to get a clear picture of your condition.

What can I do to feel better?

See your doctor right away if you develop symptoms of carpal tunnel syndrome; he or she might send you to a specialist as well. Initial treatment usually involves resting the affected hand and wrist for at least two weeks. When you return to work, these steps if your doctor okays them -- may help prevent or relieve occasional symptoms :

  • Take frequent breaks to stretch your hands and arms.
  • Avoid resting your wrists on the keyboard or edge of the desk when typing.
  • Avoid hyperextending or bending your wrists for long periods of time. If your hands and arms often feel tired, you may be holding your arms too far away from your body as you work. Some studies show that hyperextending or bending your wrists can build up extra pressure in the carpal tunnels, so try to keep your wrists in a natural, unflexed position. If you're working on a computer, your arms should be at 90 degree angles and your wrists in line with your forearm as you type.
  • If you use a wrist splint, avoid wearing it all day, since that can weaken the muscles in your wrists and hands. Wearing it all night, however, is often recommended.
  • Cut down on the amount of force you use. If you type or use a cash register, touch the keys softly; studies show that most people use four to five times more force than they need to. If you write by hand a lot, use a big pen with free-flowing ink so that you don't have to grip tightly or press hard on the paper.
  • Keep your hands warm. You're likelier to develop carpal tunnel syndrome if you work in a cold environment, surveys show. If you can't control the temperature at work, put on fingerless gloves that keep your wrists and hands warm.
  • Look into ergonomically designed equipment, especially if you think your symptoms might be related to your work. Use scissors with bigger handles if you do a lot of cutting, for example, or a trackball instead of a mouse if you're on the computer all day.
  • Take a look at yoga. A preliminary study done at the University of Pennsylvania School of Medicine found that an eight-week program of 11 specific yoga exercises for the upper body was far more effective in relieving some symptoms of carpal tunnel syndrome than either wrist splints or no treatment at all.
  • Try an over-the-counter anti-inflammatory drug such as aspirin or ibuprofen (Advil, for instance) or ice your wrists with a cold pack or a bag of frozen vegetables to reduce the pain and swelling temporarily. Don't use painkillers to work through the pain, though: Talk with your doctor about whether you need to take more time off work.
  • Get moving. Overweight, sedentary people are at much higher risk of developing carpal tunnel syndrome, so losing a few pounds or exercising more often may help keep the disorder at bay. Try to include more activity in your workday; instead of calling someone on a higher floor, for example, take the stairs occasionally.
  • Check out acupuncture. According to a statement issued by the National Institutes of Health, this traditional form of Chinese medicine is a safe option in treating many types of pain. Some studies have found that it eases the pain of carpal tunnel syndrome, but the evidence isn't as convincing as for other conditions.
  • If your symptoms are acute, your doctor may offer you the options listed below. However, be aware that your health insurance may not cover all of these treatments or tests.
  • Get steroid injections to bring down the swelling. Shot directly into the wrist, a corticosteroid such as cortisone can temporarily help reduce swelling and pain in 75 percent of cases. The extra fluid in the wrist can actually be more painful until the anti-inflammatory effect kicks in. But long-term relief from steroid injections is possible, and there are fewer risks than surgery. Diuretics taken orally may also reduce swelling and pain.
  • Consider surgery. Two main types of surgery are used to relieve the pressure on the nerves inside the carpal tunnel: open carpal tunnel release and the newer endoscopic carpal tunnel release. Both are outpatient procedures performed under local anesthesia (the surgeon cuts the ligament along the middle of the palm and inner wrist). Although surgery relieves the pain in 85 to 95 percent of the cases in which doctors recommend it, it can have such complications as accidental damage to nerves and muscles, pain at the incision, and weakness in the hand. Most people make a full recovery, but in some cases (fewer than 5 percent), carpal tunnel syndrome recurs after surgery. This happens more commonly following the endoscopic procedure, which often doesn't open up the tunnel as fully as open release.
  • Also consider modifying your job, and evaluate all your hobbies and sports to make sure they're not contributing to your pain.

References

National Institute of Neurological Disorders and Stroke. Carpal Tunnel Syndrome Fact Sheet.

MayoClinic. Carpal Tunnel Syndrome. http://www.mayoclinic.com/health/carpal-tunnel-syndrome/DS00326

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