A Pain In The Wrist A Look At Carpal Tunnell Syndrome, The Disease That Has Workers Ailing, Employers Fretting, And Doctors Busy Treating It

September 29, 1991|By ARLENE EHRLICH

IT HAD TO HAPPEN. AN 11-YEAR-OLD GIRL IS SU-ing the Nintendo company because playing Teenage Mutant Ninja Turtles gave her carpal tunnel syndrome.

That's the kind of page 10 story that most newspaper readers file under "whimsy: insignificant." But it's a symptom of a growing national problem.

It's no longer news that carpal tunnel syndrome (CTS), a potentially crippling disorder of the wrists and hands, affects millions of office and factory workers across the country and leaves product manufacturers, employers and insurers vulnerable to billions of dollars in liability and compensation claims. In fact, carpal tunnel syndrome is spreading so rapidly that it may well become in the 1990s what polio was in the 1950s and mononucleosis was in the 1960s: the Disease of the Decade. Today, carpal tunnel syndrome and related disorders account for over half of all work-related illnesses, according to the U.S. Bureau of Labor Statistics, and surgery to correct CTS is the second most frequently performed operation in the United States. Locally, for instance, the seven hand surgeons who make up the Greater Chesapeake Hand Specialists practice in Lutherville are treating between 800 and 1,000 new cases of CTS every year.

The classic symptom of CTS is numbness in the hands and fingers. "People come to us complaining that they can't hold onto anything," says Dr. Michael A. McClinton, a plastic surgeon affiliated with Union Memorial Hospital's Hand Clinic. "They can't grip a tool or a coffee cup, or they can't make their hands do what they want them to. Often they lack normal sensation in their hands, or they feel a numbness and tingling as if they'd had a shot of Novocain." In more severe cases, CTS can cause pain in the hand and wrist or even muscle atrophy in the hand.

CTS is one member of a family of diseases known as cumulative trauma disorders or repetitive stress disorders. All involve damage to nerves, tendons and associated tissues as a result of repeated biomechanical stress. In the case of CTS, compression of the median nerve, which travels down the arm, through the wrist, and into the fingers, leads to pain, numbness, and weakness in the hand.

Anyone can develop CTS, but the people most at risk are those whose jobs or hobbies involve repetitive wrist movements, forceful grasping of tools or other objects, awkward positions of the hand and wrist, direct pressure on the wrist, and use of vibrating hand-held tools. In addition, the disease frequently shows up in people with diabetes and arthritis, and in pregnant women.

Dr. Martin Z. Kanner, a Baltimore physiatrist -- that's a specialist in physical medicine and rehabilitation -- estimates that he sees about four or five new cases of carpal tunnel syndrome every week. The chief of rehabilitation medicine at Baltimore County General Hospital, Dr. Kanner finds the increase in CTS ironic.

"You'd think," he says, "that with the 20th century shift away from physical labor and toward electronics and high technology, we'd be subjecting our bodies to less trauma. But most of today's jobs seem to invite repetitive stress. Certainly there's an abundance of occupational and avocational sources of CTS. I'm seeing patients as diverse as writers, typists and secretaries, computer operators, electronic checkout scanners, assembly-line workers, post office letter sorters, carpenters, clam shuckers, gardeners, knitters and needlecrafters and musicians."

Part of the problem is the anatomy of the carpal tunnel, a narrow passage in the wrist. "There's not a lot of room in there," Dr. Kanner says. Besides the median nerve passing through that space, you also have the tendons that flex the hand and wrist, and the synovium -- the tissue that surrounds the tendons and everything else in the carpal tunnel. The "walls" of the carpal tunnel are formed by a bracelet of bones on the bottom and a tough membrane, the flexor carpal retinaculum -- or the transverse carpal ligament -- on the top. Anything that compromises that space can cause CTS.

Classically, the trauma of repetitive wrist motion causes the synovium to thicken, and the carpal tunnel becomes inflamed. ++ Or arthritis or fractures can change the structure of the bones. Edema, or water retention -- such as occurs in pregnancy -- can cause the soft tissues to swell. In any case, the result is the same; over time, the carpal tunnel space is affected, the median nerve gets compressed, and the patient starts complaining of tingling, numbness or pain.

Some physicians believe that there are two distinct kinds of carpal tunnel syndrome. "The classic case," says Dr. McClinton, "the kind that's been around for years, is a post-menopausal woman who has gradually developed symptoms over a number of years without having suffered any obvious trauma to her wrist."

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