Novel Training Environment to Normalize Altered Finger Force Direction Post Stroke

Despite the functional importance, fingertip forces are rarely explicitly addressed with feedback in therapy. This gap in treatment is due to a lack of tools to provide explicit feedback on patients' volitional finger force generation. To address this unmet need, the investigators developed a novel tool for practice of volitional three-dimensional (3D) force generation with explicit feedback. The objective of this project is to determine if 3D finger force training is an effective tool in restoring hand function post stroke.

Stroke survivors with moderate to severe hand impairment with at least palpable volitional grip force will randomly be assigned to either the experimental or control group, stratified by impairment level. Both groups will undergo 3 1-hr training sessions per week for 6 weeks in which they practice volitional finger force generation against force sensors. The experimental group will practice for various target force directions to explore the 3D force workspace and receive feedback in 3D force, while the control group will practice 1D force generation without feedback on other directional forces on a computer screen.

Training will progress by increasing influence of flexion synergy by varying posture requirements and increasing force level, introducing feedback delay, and incorporating unilateral/bilateral activity. Evaluation will occur at baseline (3 times over 3 weeks to establish baseline trends) and every 2 weeks during 6-week intervention to determine pattern of progress, and at 1-month follow-up to assess retention.