Work-Related Carpal Tunnel Syndrome-Reply

In Reply.— We believe Dr Nathan may have misunderstood the purpose of the Santa Clara physician survey. The survey was not intended to assess whether repetitive, forceful, or awkward hand movements increase the risk of CTS. That association has been firmly established in numerous studies. 1-3 Dr Nathan cites a single survey 4 as evidence against an association between occupational factors and CTS, even though workers in jobs requiring both forceful and highly repetitive hand movements did have a higher prevalence (61%) of slowed median nerve conduction than did workers in the lowest-risk jobs (28%). Reasons why an even stronger effect of ergonomic factors was not observed may include the following: the small number of subjects (23) in the highest-risk group; the exclusion of subjects with previous surgery for CTS; exposure misclassification (objective measurements of force and repetitiveness were not made); survivor bias (symptomatic workers tend to leave high-risk jobs);