Investigating muscle synergies changes after rehabilitation robotics training on stroke survivors: a pilot study

The current knowledge about muscle synergies does not clearly explain how both rehabilitation and brain plasticity act on the way they evolve after a cortical stroke. In this preliminary study, the authors analyzed the correlation between healthy and affected muscle synergies and the way the latter change after rehabilitation, following the clinical scales scores changes. The aim was finding whether the patients were supposed to get the unimpaired synergies back or develop new synergies due to neural changes. Eleven chronic stroke survivors performed 20 rehabilitation sessions with robotic hand, obtaining different scores in the assessment sessions. Results revealed no significant correlations between changes on clinical assessment scales and the difference in similarities with healthy synergies, between post and pre-assessment ones, suggesting that the stroke recovering process involves the growth of new synergies, different from the ones of healthy subjects. Those new synergies could better facilitate motor hand and elbow functions.