An Assessment of Robot-Assisted Bimanual Movements on Upper Limb Motor Coordination Following Stroke

Robot-assisted training is increasingly being investigated in upper limb rehabilitation for individuals with stroke. Many studies have suggested that an appropriate synchronization of voluntary motor commands and limb movement is critical for long-term efficacy. Bimanual training is one method for enhancing this synchronization or motor coordination. The purpose of the study was to evaluate the potential efficacy of bimanual robot-assisted movements by comparing the relative timing of muscle activation and forces to those generated during unimanual robot-assisted movement. A secondary goal was to compare bimanual robot-assisted movement to bimanual voluntary movement, where both limbs moved independently without robotics. Subjects performed reaching tasks while attached to one or two robotic manipulators. A predefined movement trajectory was prescribed during unimanual robot-assisted movement; in bimanual robot-assisted movement the paretic limb trajectory mirrored the nonparetic limb. Relative to unimanual movements, during bimanual movements the timing of muscle activation and initial interface forces was more similar to the nonparetic limb. However, there were limited differences in these measures between bimanual voluntary and bimanual robot-assisted movements. Bimanual robot-assisted movements resulted in superior motor coordination compared to unimanual movements and could be beneficial for individuals with a restricted movement range. Bimanual movements without robotics were just as efficacious and may be preferred for individuals who can generate movement without assistance.