Effect of EMG-activated vibrotactile biofeedback on skill learning in children with genetic and acquired dystonia during point-to-point and cyclic task practice

Dystonia is a movement disorder that causes involuntary muscle contractions and abnormal movements. Often, repeated practice does not lead to motor improvement in children with acquired dystonia, likely because of sensory deficits, which may contribute to their impairment. Therefore, improvements in sensory function might improve motor performance. In this study, we propose that augmented vibrotactile biofeedback may improve motor learning in children with acquired dystonia but not in children with genetic dystonia who do not have associated sensory deficits. To test this hypothesis, we obtained muscle activity and kinematic recordings and computed outcome measures that represent motor skills during the practice of a point-to-point movement and trajectory-following task. We examined the effects of applying vibrotactile biofeedback on dystonic muscles in children who are typical and those with genetic and acquired dystonia. The device significantly improved motor learning in children with acquired dystonia exclusively in the cyclic task, as evidenced by reduced error and an improved task correlation index (p < 0.01), whereas no significant effects were observed in the other groups. Our results show that the vibrotactile device potentially represents an effective method of motor improvement only for cyclic and smooth tasks but not for point-to-point tasks in children with acquired dystonia.