Workplace surveillance for carpal tunnel syndrome: A comparison of methods.
A variety of screening procedures for carpal tunnel syndrome (CTS) were applied among workers in a manufacturing plant, and results were compared. The test procedures included a symptom survey, physical examination, limited electrodiagnostic testing at the wrists, quantitative vibratory threshold testing, 2-point discrimination, palmar pinch grip, and hand grip strength testing. When electrodiagnostic testing alone was used as "gold standard," the sensitivity and positive predictive value (PPV) of physical examination findings and quantitative test procedures were no better than, and usually worse than, the results on the symptom survey alone. Variation of the constellation of symptoms (i.e., numbness, tingling, pain or burning) and the anatomic distribution of reported symptoms (i.e., fingers, hand, wrist, or forearm) for inclusion in the screening symptom definition of CTS yielded modest changes in the sensitivity and PPV of the symptom survey. However, addition of the requirement for nocturnal symptoms as part of the screening symptom definition for CTS resulted in substantially higher PPV with only slight reduction in sensitivity. These results suggest that, in the absence of electrodiagnostic testing, the simplest test, and the procedure with the highest sensitivity and PPV for CTS is a symptom survey alone. Quantitative test procedures (vibrometry, pinch grip strength, hand grip strength) and physical examination for findings consistent with CTS (e.g., Phalen's test, Tinel's test, thenar muscle wasting, 2-point discrimination) appear to contribute little, if any, additional information when screening subjects in the work setting.
Department of Environmental and Industrial Health, University of Michigan School of Public Health, 1420 Washington Heights, 48109-2029, Ann Arbor, Michigan.
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A
Franzblau
R
R
Werner
J
J
Valle
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E
Johnston