Feedback-based training of grip force control in patients with brain damage

Abstract

Objective: Feedback-based training of grip force control in patients with various brain lesions was evaluated. Design: Patients were instructed to hold a force transducer in a precision grip and to track with their grip force a moving target, which was presented together with the feedback signal on a monitor. Training performance was evaluated during a maximum of 10 sessions. Before and after the training, performance in two transfer tasks, which differed in target characteristics from the training task, was examined. Patients: Ten patients with impaired grip force control, after brain lesions of different origin, were selected on the basis of a clinical examination of hand function. Main Outcome Measures: Tracking accuracy in training tasks and transfer tasks was evaluated by calculating the conventional root-mean-square error. Results: Nine out of the 10 patients reduced their tracking error considerably during a maximum of 10 subsequent sessions ( t test, p < 0.05), and most of them reached normal or near-normal performance. In addition, they improved in both transfer tasks ( t test, p < 0.05). Detailed analysis showed that impaired initial performance and improvement was not uniform among patients and could be attributed to individual aspects of force control. Conclusions: In view of these results, a feedback-based training of grip force may be a useful enrichment of motor therapy.