The Effects of Dynamic Wrist Workloads on Nerve Conduction Measures for Evaluating Carpal Tunnel Syndrome

Abstract

The effects of exposure to three hours of forceful exertion and repetitive movement on nerve conduction function were examined in fifteen subjects. Wrist workload was recorded by using biaxial electrogoniometer and force resistance sensor, while the nerve conduction measures were recorded with TECA TD-20 EMG machine. The results of peak latency showed an overall increase during task performance for high force-low repetition, low force-high repetition, and low force-low repetition conditions, while little change for high force-high repetition condition. Analysis of variance on peak latency detected significant effect on time (p<0.001, F=13.79). For amplitude, overall increases for all workload conditions were found until 60 minutes into task performance, but after that time, amplitudes stayed relatively level. As expected, skin temperature had highly significant correlation with peak latency (p<0.001, r²=0.736), where peak latency appeared to increase as skin temperature decreased. These same results were found for peak latency and amplitude after skin temperature corrections. Correlation analyses indicated that the maximum wrist flexion, maximum range of motion and cumulative exposure time had highly significant relationships with peak latency and temperature-corrected peak latency over time. Specifically, the cumulative exposure time of F/E angle > 30° may serve as the best predictive measure for investigating the effects of dynamic wrist workloads on the nerve conduction.