The overall goal of the proposed work is to improve hand function after stroke. Adequate hand function is critical to a functional upper limb, and is often resistant to conventional therapeutic interventions. Many stroke survivors have residual ability to flex the fingers, but extension is often limited and impeded by increased passive stiffness in flexors, involuntary activation of flexors and inability to activate extensors. The rationale for this approach stems from the growing evidence that neuro-rehabilitation after stroke may be enhanced via the application of motor learning strategies within the context of repetitive movement practice. The key therapeutic aspects of these strategies are high repetition, volitional effort, and successful completion of tasks to prevent frustration. While these represent promising therapeutic strategies, they are limited to mildly impaired subjects who already have enough control of finger extension to tolerate high repetitions of grasp/release tasks without succumbing to fatigue and/or frustration. There is a very large population of stroke patients who don't fall into this category and often must rely on compensatory strategies. In these patients, repetitive task practice facilitated by a robotic device may be more effective than unassisted task practice.
A study will be performed where individuals with chronic stroke will be randomly assigned to receive 2 different dosages of robotic hand therapy. One group will receive 12 sessions of robot-assisted repetitive movement practice in the HEXORR robot over a 4-5 week period. A second group will receive 24 sessions of HEXORR therapy over a 8-10 week period.