Myoelectric Computer Interface Training for Reducing Co-Activation and Enhancing Arm Movement in Chronic Stroke Survivors: A Randomized Trial

Abstract

Background. Abnormal muscle co-activation contributes to impairment after stroke. We developed a myoelectric computer interface (MyoCI) training paradigm to reduce abnormal co-activation. MyoCI provides intuitive feedback about muscle activation patterns, enabling decoupling of these muscles. Objective. To investigate tolerability and effects of MyoCI training of 3 muscle pairs on arm motor recovery after stroke, including effects of training dose and isometric versus movement-based training. Methods. We randomized chronic stroke survivors with moderate-to-severe arm impairment to 3 groups. Two groups tested different doses of isometric MyoCI (60 vs 90 minutes), and one group tested MyoCI without arm restraint (90 minutes), over 6 weeks. Primary outcome was arm impairment (Fugl-Meyer Assessment). Secondary outcomes included function, spasticity, and elbow range-of-motion at weeks 6 and 10. Results. Over all 32 subjects, MyoCI training of 3 muscle pairs significantly reduced impairment (Fugl-Meyer Assessment) by 3.3 ± 0.6 and 3.1 ± 0.7 (P < 10 −4) at weeks 6 and 10, respectively. Each group improved significantly from baseline; no significant differences were seen between groups. Participants' lab-based and home-based function also improved at weeks 6 and 10 (P ≤ .01). Spasticity also decreased over all subjects, and elbow range-of-motion improved. Both moderately and severely impaired patients showed significant improvement. No participants had training-related adverse events. MyoCI reduced abnormal co-activation, which appeared to transfer to reaching in the movement group. Conclusions. MyoCI is a well-tolerated, novel rehabilitation tool that enables stroke survivors to reduce abnormal co-activation. It may reduce impairment and spasticity and improve arm function, even in severely impaired patients.

A Virtual Reality Muscle–Computer Interface for Neurorehabilitation in Chronic Stroke: A Pilot Study

“…al. found that six sessions of EMG-based training to reduce co-contraction was able to improve FMA-UE scores of 32 moderate-to-severe stroke survivors by an average of about 3 points [24]. This is the closest in design to the current study and confirms that this type of training can be of benefit in a larger population.…”

“…We hypothesized that that (1) reinforcement of EMG activity in participants with severe movement deficits would be feasible, safe, and provide a positive user experience for participants; (2) training would produce modest improvements in clinical assessments comparable to what we have previously observed for EEG-based neurofeedback (i.e., variable improvement across individuals, but with some participants showing clinically meaningful effects); and (3) that we would observe evidence of improved neuromuscular control as indexed by task performance and by enhanced beta band (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) Hz) corticomuscular coherence. Finally, we expected that participants who showed strong post-training changes in clinical assessments and neuromuscular control would also show large improvements in task performance during training, assuming that within-task performance is sensitive to training-induced neural plasticity.…”

“…Consistent, significant corticomuscular coherence was observed only during static holding of wrist extension and not during flexion. Pooled coherence across participants shows that, during maintained wrist extension, the only significant coherence occurred within the beta band (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and only after training ( Figure 4A, top, ipsilesional: Z-score pre-post difference = 2.57, p = 0.010; contralesional: Z-score pre-post difference = 3.29, p = 0.001). After training, the composite difference of coherence, that is, the averaged coherence within each frequency band, was evaluated ( Figure 4A bottom, horizontal lines at Z-score = 1.96 indicate the threshold for significance at p < 0.05 level), and showed a significant effect of training only for the beta band.…”

“…Although we assumed that EMG would be detectable in anyone without severe flaccid paralysis, the utilization of very weak EMG within an entirely EMG-based training program has not been commonly reported for our targeted study population, leaving the feasibility of this approach unclear. One pilot study [25] and a later follow-up [24] demonstrated that a muscle-computer interface could be used to uncouple pairs of shoulder/elbow muscles. However, our task focused specifically on promoting individuated wrist extensor activity in participants with little to no functional wrist movement.…”

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

“…Almost four decades later the authors reported on similar ndings in persons with chronic stroke. The participants reduced the co-activation of arm muscles in isometric conditions using EMG biofeedback with 3 pairs of muscles in combination with computer games [13]. 32 moderately or severely impaired participants showed signi cant improvement of range of motion, muscle co-activation and a potential for reducing spasticity.…”