Levels of agreement of nerve conduction studies and symptoms in workers at risk of carpal tunnel syndrome

Abstract

Objective: Information is required on levels of agreement between different sets of median nerve conduction studies (NCS) and symptoms of carpal tunnel syndrome (CTS) in at-risk subjects.

Methods: We performed a reanalysis of an extensive data set from a population of 114 "highly exposed" meat workers (without prior diagnosis of CTS), who were interviewed for the presence of current symptoms typical of CTS and systematically submitted to median NCS.

Results: Agreement between presence/absence of symptoms and NCS normal/abnormal findings ranged from 81% for wrist sensory latency (WSL) to 49% for motor conduction velocity wrist-to-palm (MCV-WP) in the nondominant hands (from 60% to 50%, respectively, in the dominant hands). Mean values of WSL, sensory conduction velocity-WP (SCV-WP), wrist motor latency, MCV-WP, and the SCV-WP/SCV-elbow-to-wrist ratio all showed significant differences between symptomatic and asymptomatic workers. In nondominant hands, these parameters all reached significant P values at chi-squared tests for kappa coefficients of agreement, the best kappa coefficients being 0.57 for WSL and 0.40 for SCV-WP. However, in the dominant hand only SCV-WP reached significance (kappa coefficient=0.20).

Conclusions: Given the importance of the dominant hand in working populations, these data support use of SCV-WP (or WSL) as an informative NCS parameter for occupational studies on CTS.