GENERALIZATION OF REPETITIVE BILATERAL TRAINING IN STROKE

Abstract

Background & Purpose: Bilateral Training (BT) is an alternative approach in neurorehabilitation for individuals post stroke. Bilateral training activities may increase the activity of the affected hemisphere and decrease the activity in the unaffected hemisphere providing a balancing effect between hemispheric corticomotorneuron excitability. One bilateral approach; repetitive rhythmic bilateral training, developed and researched by Whitall has shown improved motor function after intervention post stroke. Repetitive motions may excite the spinal central pattern generators to help increase motor ability. Yet, an important question is whether this type of practice will result in improvements in untrained movements. The ability to perform related untrained motor tasks is generalization. The purpose of this study is to determine if repetitive rhythmic bilateral training will promote spatial generalization to a novel task. Case Description: Fifteen participants with hemiparesis were recruited with 14 completing the study. The intervention used an arm training machine-BATRAC consisting of two paddles mounted in nearly frictionless tracks. The participants moved the handles back and forth in a rhythmic manner for 5-minute blocks with 10-minute breaks between blocks to minimize fatigue. Half of the blocks were in-phase, the other half of the blocks were anti-phase. Practice sessions were 4 days/week, 2:25 hours/ day, for 2 weeks, for a total of 18 hours of training. Participants were pre and post tested. We measured movement time, time to peak velocity, hand path trajectory, peak velocity, smoothness of the curve and acceleration using the Vicon motion analysis system during 2 reach to target tasks. Each participant gave informed consent according to University of Florida Institutional Review Board and North Florida/South Georgia Subcommittee for Clinical Investigation requirements prior to participation. Outcomes: Improvements were found at posttest only for hand path trajectory, smoothness of the curve and peak velocity. They were equivalent across similar and dissimilar tasks. Discussion: Unlike Whitall, the kinematic results suggest that repetitive rhythmic bilateral training alone is not sufficient practice to effect a change in motor control specifically generalization to untrained motor tasks even for a task with very similar demands. The practice intensity in this study, condensing the practice over a shorter period of time compared to Whitall's study, may have affected the lack of generalization observed at posttest. However, the small sample size and heterogeneous study sample preclude defnitive conclusions regarding the usefulness of this practice paradigm for promoting motor skills post stroke.