When exactly can carpal tunnel syndrome be considered work-related?

BACKGROUND: Carpal tunnel syndrome (CTS), compression of the median nerve at the wrist, is the most frequently encountered peripheral entrapment neuropathy. Whilst rates of all other work-related conditions have declined, the number of work-related musculoskeletal disorders (which include CTS) has not changed for the past 9 years in the USA. Median days off work are also highest for CTS: 27 compared to 20 for fractures and 18 for amputations. This results in enormous Workers Compensation and other costs to the community. Awareness of CTS as a disorder associated with repeated trauma at work is now so widespread amongst workers that many have diagnosed themselves before being medically assessed, often by means of the Internet. Surprisingly, however, a definite causal relationship has not yet been established for most occupations. Although the quality of research in this area is generally poor, CTS research studies are being used as the basis for acceptance of Workers Compensation claims, substantial expensive ergonomic workplace change and even workplace closures. The fact that the incidence of work-related musculoskeletal disorders has not changed despite these latter measures would suggest that a causal relationship is not proven and that some resources are being misdirected in CTS prevention and treatment.
METHOD: A literature review of 64 articles on CTS was conducted. This included those articles most frequently cited as demonstrating the relationship between CTS and work.
RESULTS: Primary risk factors in the development of CTS are: being a woman of menopausal age, obesity or lack of fitness, diabetes or having a family history of diabetes, osteoarthritis of the carpometacarpal joint of the thumb, smoking, and lifetime alcohol intake. In most cases, work acts as the 'last straw' in CTS causation.
CONCLUSION: Except in the case of work that involves very cold temperatures (possibly in conjunction with load and repetition) such as butchery, work is less likely than demographic and disease-related variables to cause CTS. To label other types of work as having caused CTS, therefore, would result in inappropriate allocation of resources. It would also relieve individuals of the responsibility of addressing correctable lifestyle factors and treatable illnesses such as obesity, diabetes, smoking and increased alcohol intake which may have contributed to their CTS more that their work. This results in both avoidable long-term health effects and ongoing costs to the community.