Carpal Tunnel Syndrome
The carpal tunnel receives its name from the 8 bones in the wrist, called carpals, that form a tunnellike structure. The tunnel is filled with flexor tendons which control finger movement. It also provides a pathway for the median nerve to reach sensory cells in the hand. Repetitive flexing and extension of the wrist may cause a thickening of the protective sheaths which surround each of the tendons. The swollen tendon sheaths, or tenosynovitis, apply increased pressure on the median nerve and produce Carpal Tunnel Syndrome (CTS).
The Facts
In the past ten years, more and more cases of workers afflicted with CTS have been reported in medical literature. One reason for this increase may be that automation and job specialization have fragmented workers' tasks to the point where a given job may involve only a few manipulations performed thousands of times per workday.
Increased awareness of work-related risk factors in the onset of CTS is reflected in the growing number of requests for health hazard evaluations (HHEs) received by NIOSH to investigate such suspected problems. NIOSH received about three times as many HHE requests related to hand and wrist pain in 1992 as compared to 1982.
Symptoms
- Painfully tingling in hand(s) that usually starts at night but may progress to day symptoms as well
- Feeling of the hands being swollen without actual swelling
- A decreased ability to squeeze things
- Loss of strength in fingers
- Clumsiness in the hand(s)
- Unable to differentiate hot from cold
What Causes CTS?
As stated earlier, swelling of the tendons that line the carpal tunnel causes CTS. Although there are many reasons for developing this swelling of the tendon, it can result from repetitive and forceful movements of the wrist during work and leisure activities. Research conducted by the National Institute for Occupational Safety and Health (NIOSH) indicates that job tasks involving highly repetitive manual acts, or necessitating wrist bending or other stressful wrist postures, are connected with incidents of CTS or related problems. The use of vibrating tools also may contribute to CTS. Moreover, it is apparent that this hazard is not confined to a single industry or job but occurs in many occupations especially those in the manufacturing sector. Indeed, jobs involving cutting, small parts assembly, finishing, sewing, and cleaning seem predominantly associated with the syndrome. The factor common in these jobs is the repetitive use of small hand tools.
Prevention
NIOSH recommendations for controlling carpal tunnel syndrome have focused on ways to relieve awkward wrist positions and repetitive hand movements, and to reduce vibration from hand tools. NIOSH recommends redesigning tools or tool handles to enable the user's wrist to maintain a more natural position during work. Other recommendations have involved modified layouts of work stations. Still other approaches include altering the existing method for performing the job task, providing more frequent rest breaks, and rotating workers across jobs. As a means of prevention, tool and process redesign are preferable to administrative means such as job rotation.
Treatment
Treatment of CTS may involve surgery to release the compression on the median nerve and/or use of anti-inflammatory drugs and hand splinting to reduce tendon swelling in the carpal tunnel. Such medical interventions have met with mixed success, especially when an affected person must return to the same working conditions.
