In reply to the letter to the editor titled 'Is carpal tunnel syndrome overdiagnosed?', I would like to make several points. First, I would like to clarify that we did not observe any association between arm elevation and carpal tunnel syndrome (CTS) in our data. The only mention of arm elevation in our manuscript was to report in the discussion section that the inter-rater reliability of posture observations was higher for arm elevation than it was for wrist postures. The case definition was discussed among several research groups in USA who have met for several years to discuss such issues as part of a musculoskeletal disorder research consortium. Although each institution has carried out independent research, and their case definitions for CTS are not identical, all agreed that the components would include nerve conduction testing and symptoms recorded on hand diagrams, but not physical examination findings. In the case of our study at the National Institute for Occupational Safety and Health (NIOSH), the health assessment portion of our study included physical examinations, nerve conduction tests and questionnaires administered to all study subjects during site visits to participating workplaces. Our physical examinations included the neck, shoulder and proximal upper limb as well as the forearm, wrist and hand, on all study subjects. However, because the timing of the data collection for our prevalent CTS study was cross-sectional, a physical examination is less informative than it would be for a patient scheduling a medical appointment soon after experiencing symptoms. We inquired about symptoms that had occurred within the past year; those who met the criteria for frequency, duration, type and location of symptoms recorded on hand diagrams and who also met the electrodiagnostic criteria met our case definition. Hand diagram analysis differentiated symptoms in the ulnar and radial distributions from the median distribution. Ulnar nerve testing was done to rule out generalised peripheral neuropathy. Nerve conduction testing is our only objective indication of possible CTS. We feel that it is a strength of our study that our electrodiagnostic criteria are the same as those recommended for clinical use. However, we made it clear to our study participants that we were not making any clinical diagnoses. In response to Dr Jepsen's question about how to advise workers identified with CTS, I will describe our process at NIOSH. All study participants were sent notification letters with their individual results and general interpretations such as 'According to our research criteria, your nerve conduction results are consistent with possible CTS' or 'At least one of your nerve conduction test results was not normal, according to the guidelines that we use in our research studies. Although the results of your nerve conduction test do not meet our criteria for possible CTS, it is possible that another health problem may exist'. This was followed by an explanation that nerve conduction testing alone would not determine whether CTS or another health problem was present and advice was given to follow-up with their own healthcare providers. Upon request by the study participants, the results of our testing and physical examinations were also sent to the individuals' healthcare providers. Group level results were provided to participating companies. Specific exposure information was also provided on request, along with recommendations for reducing exposure. For example, we presented the type of jobs that required exertions with high hand force that might become the focus of preventive interventions.
Carpal-tunnel-syndrome; Exposure-assessment; Injury-prevention; Posture; Repetitive-work; Work-analysis; Musculoskeletal-system-disorders; Extremities; Body-mechanics; Body-regions; Nerve-function; Physical-examination; Questionnaires; Workplace-studies; Diagnostic-techniques; Health-care; Health-services
Dr Susan Burt, Industrywide Studies Branch, Division of Surveillance Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Mail Stop R-15, Cincinnati, OH 45226, USA