July 1, 2007 Doctors have found evidence that carpal tunnel syndrome develops after an injury shears the tissue that lines tendons within the carpal tunnel. As the injury heals, the resulting scar tissue impedes the sliding motion of the tendons, compresses the nerve, and cuts off the nerve's blood supply. The scarring fuses the tendons together, causing the pain and pressure buildup characteristic of the syndrome.
About five percent of people suffer from carpal tunnel syndrome. That's a pinched nerve near the palm of your hand that cuts off circulation causing pain, tingling and numbness. No one really knows what causes carpal tunnel syndrome, but one doctor at the Mayo Clinic says he's found some clues.
Simple tasks like unscrewing a cap or stirring brownie batter used to be a real pain for Elisa Underhill. "I could have never [mixed brownie batter like] this before with [a] small spoon and gripping it and stirring. That would have been really difficult and painful," Underhill says. Underhill suffers from carpal tunnel syndrome ý in both hands!
Statistics show women are twice as likely to get carpel tunnel as men. And it's not necessarily those who work on a keyboard. Doctors say the injury is often seen in factory workers, often as result of picking up something awkward.
Orthopedic surgeon Peter Amadio compares the lining of a healthy tendon to baklava -- multiple layers with air between them. Normally, tendons slide easily, but in CTS, the layers are all stuck together and can't slide. "One tendon moving against another might shear or tear this lining and break it and when it heals with scar tissue all the layers glue together." He hopes to learn why some people develop CTS and other people heal normally from this kind of injury. "Then it would give us the possibility to intervene with something other than surgery and much earlier in the process."
This may not help patients like Underhill, but could be good news for the next generation.
BACKGROUND: Researchers at the Mayo Clinic have found evidence that carpal tunnel syndrome begins with a shearing injury of the tissue that lines the tendons within the carpal tunnel. As the injury heals, the resulting scar tissue impedes the sliding motion of the tendon, compresses the median nerve, cuts off the nerve's blood supply, and eventually leads to the pressure buildup characteristic of carpal tunnel. This could lead to earlier diagnosis and possibly better treatments for preventing or reversing carpal tunnel.
ABOUT CARPAL TUNNEL SYNDROME: Carpal tunnel syndrome is a pressure buildup in the carpal tunnel that affects the circulation nourishing the nerves. This can lead to pain, numbness and tingling. Although carpal tunnel is a well-known condition, the specific cause is unknown. While rest, exercise and some medications can treat carpal tunnel, severe carpal tunnel syndrome usually requires surgery to release the pressure buildup. The Mayo study compared electron microscope images of tissue affected by carpal tunnel syndrome with images of normal tissue. Why does the pressure increase? Healthy tissue looks like puffed pastry, many multiple layers with air in between, and these different layers slide on top of each other. But in carpal tunnel, the tissue lining around the tendon becomes thickened, or gummed up, preventing the natural sliding motion of the tissue layers. Understanding how carpal tunnel develops before the nerve becomes damaged gives doctors the chance to spot the disease progression at an earlier stage and stop it before permanent damage occurs -- possibly by using biomarkers to test people at risk.
WHAT IS ERGONOMICS: This is a branch of science that strives to design the job to fit the worker, rather than the other way around. In the modern office, it most commonly relates to the physical stresses placed on joints, muscles, nerves, tendons, bones, even hearing and eyesight, along with other environmental factors that can adversely affect comfort and health. Ergonomics deals with the interaction of technology and work environments with the human body, and involves anatomy, physiology and psychology in the design of chairs, desks, computer accessories, the design of car controls and instruments -- in short, any kind of product that could help relieve potential repetitive strain from a given job or task.
TO AVOID REPETITIVE STRESS INJURIES: -- Raise or lower chairs to avoid typing with your wrists at an odd angle. -- Place your keyboard at a level slightly lower than normal desk height. -- Use a footrest to avoid dangling your legs. -- While typing, wrists should not be bent up, down or to the side. The knuckle, wrist and top of the forearm should form a straight line. -- Elbows should form a 90-degree angle while hanging at the sides from the shoulders, and the shoulders should remain relaxed in a lowered position while typing. -- Do not use wrist supports or rests while you are typing, only when pausing to rest. -- Take frequent breaks from repetitive tasks to give your body a rest.
Further information: http://mayoresearch.mayo.edu/mayo/research/staff/amadio_pc.cfm
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.