To reduce risk factors that lead to Carpal Tunnel Syndrome, consider the following:
“Your desk and chair must be considered as a unit.”
What is Carpal Tunnel Syndrome?
Carpal Tunnel Syndrome, according to Taber’s Medical Dictionary, is defined as:
“A repetitive motion injury causing pain or numbness that affects some part of the median nerve distribution of the hand and may radiate into the arm.”
Carpal Tunnel Syndrome is a cumulative trauma disorder (a/k/a musculoskeletal disorder) that affects the nerves.
Musculoskeletal nerve disorders include:
- nerve compression,
- nerve entrapment, and
- vibration-induced problems (1).
What causes Carpal Tunnel Syndrome?
- Repetitive motion of the hands and wrists;
- External Compression of the wrists;
- Internal Compression of the wrists.
The repetitiveness of today’s light work concentrates the workload on fewer, smaller, muscle groups, such as the hands and the wrists (2).
Repetitive motion causes tissue damage and is usually associated with:
- keying activities and computer use, or
- use of vibrating tools or hand tools.
External compression with impairment of nerve function may occur from contact stress between body parts and hard work surfaces or sharp edges (1).
Internal compression may occur from increased compartmental pressures (inside the wrists) or from contact against bones, tendons, or ligaments.
One Hour of Elevated Pressure within the Carpal Tunnel Can Result in Impairment
It has been shown that within one hour elevated pressures within the carpal tunnel can result in impaired nerve function.
Even brief increases in pressure within the wrist can cause impairment.
In addition, relatively low fingertip loads raise carpal tunnel pressure significantly (1).
Flexed Wrists are a Risk Factor for Carpal Tunnel Syndrome
For individuals engaged in activities requiring flexed wrists for as few as 8 to 19 hours per week (averaging approximately 1.5 to 4 hours per day) the odds of suffering Carpal Tunnel Syndrome has been shown to be 3 times greater than for individuals engaged in activities that did not require flexed wrists.
Extended Wrists are a Risk Factor for Carpal Tunnel Syndrome
For individuals engaged in activities that required extended wrists for as few as 8 to 19 hours per week, the odds of suffering Carpal Tunnel Syndrome were shown to be 2.3 times greater than for individuals engaged in activities that did not require extended wrists (1).
How should I hold my wrists to prevent Carpal Tunnel Syndrome?
Each person should also be taught how to hold their wrists to avoid tension on the median nerve which runs through the wrists.
Five factors to consider in association with Carpal Tunnel Syndrome are:
- Lack of worker selection and training to prevent hazards;
- Poor ergonomic design of the workplace and tasks, including organization;
- Poor working posture;
- Lack of task variation;
- Insufficient rest breaks.
How should I sit to prevent Carpal Tunnel Syndrome?
- Adjust your chair so your elbows hang comfortably at your sides with your hands just above the level of the keyboard.
- Once adjusted, you should not have to raise your hands above elbow level or lower them below elbow level.
- When typing or using your mouse, do not bend your wrists and hands back toward you. This could pinch your median nerve or cause inflammation.
- Do not bend your wrists or hands down. This also could pinch your median nerve or cause inflammation.
- Try to type with a light touch to reduce force, which is a risk factor for carpal tunnel syndrome.
The fingers of a typist may exert up to 25 tons of force each day (1).
How should I work to prevent Carpal Tunnel Syndrome?
- Try to vary the tasks you are doing and change tasks every two hours.
- Rotate between repetitive and non-repetitive tasks throughout the day, if possible.
- Occupational Safety and Health Administration, U.S. Department of Labor, “Pathogenesis and Pathophysiologic Evidence for Work-Related Musculoskeletal Disorders,” 2000.
- Scandinavian Journal of Work and Environmental Health, 1994; 20:417-26, “Job Task and Psychosocial Risk Factors for Work-Related Musculoskeletal Disorders Among Newspaper Employees,” written by Bruce Bernard, M.D.; Steve Sauter, Ph.D.; Lawrence Fine, M.D.; Marten Petersen, Ph.D.; and Thomas Hales, M.D.
- American Journal of Industrial Medicine 19:87-107 (1991), “Workplace Ergonomic Factors and the Development of Musculoskeletal Disorders of the Neck and Upper Limbs: A Meta-Analysis,” written by Susan Stock, M.D., U.S.A.