Carpal tunnel syndrome impairs sustained precision pinch performance

Objective: The purpose of this study was to investigate effects of carpal tunnel syndrome (CTS) on digit force control during a sustained precision pinch. Methods: Eleven CTS individuals and 11 age- and gender-matched healthy volunteers participated in the study. The subjects were instructed to isometrically pinch an instrumented apparatus for 60 s with a stable force output. Visual feedback of force output was provided for the first 30 s but removed for the remaining 30 s. Pinch forces were examined for accuracy, variability, and inter-digit correlation. Results: CTS led to a decrease in force accuracy and an increase in amount of force variability, particularly without visual feedback (p < 0.001). However, CTS did not affect the structure of force variability or force correlation between digits (p > 0.05). The force of the thumb was less accurate and more variable than that of the index finger for both the CTS and healthy groups (p < 0.001). Conclusions: Sensorimotor deficits associated with CTS lead to inaccurate and unstable digit forces during sustained precision pinch. Significance: This study shed light on basic and pathophysiological mechanisms of fine motor control and aids in development of new strategies for diagnosis and evaluation of CTS. (C) 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.