Robotic Wrist Rehabilitation With High-density Electromyographic Biofeedback for Reducing Co-activation of Antagonist Muscles and Improved Motor Coordination: A Feasibility Study

Abstract

Objectives: Electromygraphic (EMG) biofeedback has been successfully applied in stroke survivors for a few decades. Recently high-density (HD) electrodes were introduced in research and diagnostic EMG. The application of such electrodes may increase the reliability and selectivity, but requires information reduction for real-time biofeedback. We tested whether the use of the proposed feedback is feasible in minimization of inappropriate co-activation of wrist flexors/extensors controlled by the wrist rehabilitation robot. Methods: The EMG of wrist flexors and extensors muscles has been assessed by arrays of 5 x 13 electrodes, reduced to 1 x 4 information matrix and provided as real-time biofeedback during wrist movement controlled by the robot. The designed task required to keep the contribution of agonist muscles within predefined limits. A feasibility study with a single patient with stroke was conducted to examine force tracking and reduction of activity of antagonists wrist muscles in 4 weeks. Results: Force tracking signal and cumulative forecast errors decreased in 4 trials. The RMS activity of antagonist muscles significantly decreased (Kruskal Wallis, c2 = 3.330*10-9) during wrist flexion in the 4th week of trials. The participant was able to follow the reduced HDEMG biofeedback.Conclusions: The outcomes show that the surface HDEMG biofeedback has a potential to decrease the co-activation of antagonist muscles, wrist flexion in particular. Additionally the combination of force tracking and robot assisted biofeedback training may recover selective hand function in stroke survivors who would less likely to develop contractures. Trial registration: The study is not a clinical trial. While human subjects are involved, they do not participate in a full rehabilitation intervention, and no health outcomes are examined.