Adapted from “Carpal Tunnel Syndrome,” published by Canadian Centre for Occupational Health and Safety

Carpal tunnel syndrome is a condition affecting the hand and wrist. The carpal tunnel is a space in the wrist surrounded by wrist bones and by a rigid ligament that links the bones together.

Through this small tunnel pass the flexing tendons of the fingers and thumb - which attach muscles to bones in the hand and transfer the movement of the fingers from muscles to bones, and the median nerve - which carries signals from the brain to control the actions of the fingers and hand.

In the carpal tunnel, the tendons of the fingers surround the median nerve. Swelling of the tendons reduces the space in the tunnel and squeezes the median nerve, which is softer than the tendons. Pressure on this nerve can injure it.

Such injury results in sensations of numbness, tingling, pain, and clumsiness of the hand – the combination of symptoms called carpal tunnel syndrome. People with carpal tunnel syndrome experience difficulty in performing tasks such as unscrewing bottle tops, fastening buttons, or turning keys.

Carpal tunnel syndrome is particularly associated with certain tasks including repetitive hand motions, awkward hand positions, strong gripping, mechanical stress on the palm, and vibration. Some studies show that psychosocial factors (such as stress) can contribute to the development of carpal tunnel syndrome.

Some of the most common tasks and related occupations associated with carpal tunnel syndrome include pushing down a ratchet or using a screw driver, using a spray gun, assembling small parts, wearing poorly fitting gloves which apply external pressure, pressing tool into palm, and using air-powered hand tools.

The typical symptoms of carpal tunnel syndrome are tingling of the thumb, and of the index, middle, and ring fingers, and night pain. The pain awakens the patient, but is often relieved by shaking, hanging, or massaging the hand. Pain may involve not only the hand, but also the arm and the shoulder. Numbness and loss of manual dexterity occur in more advanced cases. Weakness of the hand also occurs, causing difficulty with pinch and grasp. The person may drop objects or be unable to use keys or count change with the affected hand. The skin may dry because of reduced sweating.

People who suspect carpal tunnel syndrome often consult a doctor. The evaluation of occupational carpal tunnel syndrome includes identifying workplace risks. Evaluation begins with a discussion of the person’s employment and requires a detailed description of all the processes involved in a typical day’s work. It also requires consideration of the frequency, intensity, duration, and regularity of each task performed at work. Diagnosis of carpal tunnel syndrome is confirmed by performing certain tests to detect damage to the median nerve.

When symptoms of carpal tunnel syndrome are mild or likely to be temporary, treatment includes rest, anti-inflammatory drugs, and a splint. Even if a patient wears a splint that has been prescribed, he or she should avoid the activities that caused or aggravate the injury. Where this is not possible, patients should wear the splint after work and particularly during sleeping hours. Specific exercises supervised by a physical or occupational therapist and yoga can be beneficial.

Surgery may be necessary if the symptoms are severe and if the other measures do not provide any relief. Surgery should not be the first choice for treatment. Even after surgery, a number of patients may still have some problems. Weakness of grip in the operated hand persists in about 30 percent of cases.

Prevention of carpal tunnel syndrome may involve redesigning work stations, tools, or the job, and educating workers. Proper work station design reduces awkward wrist positions and minimizes the stressful effects of repetitive motions. Awkward positions can originate from unsuitable work station designs that do not take into account the size and proportions of the human body. Work stations should be adjustable and should accommodate a vast majority of people who work in that area.

Redesigning work methods is important. For example, using an adjustable fixture to hold an electrical housing reduces wrist flexion. Redesigning tools is also important. Good job design minimizes awkward wrist positions and tasks with repetitive motions. Job design includes the following analysis of the sequence of the tasks to allow changes in body position, work-rest schedule to relieve muscles from mechanical stress, work breaks to avoid monotonous and repetitive patterns of work, and rotation of tasks to move workers from one job to another.

To limit the effects of a physically stressful job, employers should work closely with employees. This is achieved by implementing worker training and job rotation, and by matching employees to job assignments. CPT

Canadian Centre for Occupational Health and Safety www.ccohs.ca

Full article available at www.ccohs.ca/oshanswers/diseases/ carpal.html?print