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.