Arm Stiffness During Assisted Movement After Stroke: The Influence of Visual Feedback and Training

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 21; no. 3; pp. 454 - 465
• Main Authors: Piovesan, Davide, Morasso, Pietro, Giannoni, Psiche, Casadio, Maura
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.05.2013; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptation, Physiological; Adult; Aged; Arm - physiopathology; Arm impedance; Biofeedback, Psychology - methods; Elastic Modulus; Feedback; Feedback, Sensory; Female; Force; Humans; Impedance; Learning; Male; Middle Aged; Motion Therapy, Continuous Passive - methods; Muscles; Robot sensing systems; robot therapy; Robotics - methods; stiffness; Stroke; Stroke - physiopathology; Stroke Rehabilitation; Therapy, Computer-Assisted - methods; Training; Treatment Outcome; Visualization
• ISSN: 1534-4320; 1558-0210; 1558-0210
• DOI: 10.1109/TNSRE.2012.2226915

Spasticity and muscular hypertonus are frequently found in stroke survivors and may have a significant effect on functional impairment. These abnormal neuro-muscular properties, which are quantifiable by the net impedance of the hand, have a direct consequence on arm mechanics and are likely to produce anomalous motor paths. Literature studies quantifying limb impedance in stroke survivors have focused on multijoint static tasks and single joint movements. Despite this research, little is known about the role of sensory motor integration in post-stroke impedance modulation. The present study elucidates this role by integrating an evaluation of arm impedance into a robotically mediated therapy protocol. Our analysis had three specific objectives: 1) obtaining a reliable measure for the mechanical proprieties of the upper limb during robotic therapy; 2) investigating the effects of robot-assisted training and visual feedback on arm stiffness and viscosity; 3) determining if the stiffness measure and its relationship with either training or visual feedback depend on arm position, speed, and level of assistance. This work demonstrates that the performance improvements produced by minimally assistive robot training are associated with decreased viscosity and stiffness in stroke survivors' paretic arm and that these mechanical impedance components are partially modulated by visual feedback.