Use of Sensory Substitution to Improve Arm Control After Stroke

Supplementing or augmenting sensory information to those who have lost proprioception after stroke could help improve functional control of the arm. Thirty subjects will be recruited to a single site to evaluate the ability of supplemental kinesthetic feedback (a form of vibrotactile stimulation) to improve motor function. Participants will be tested in performing reaching movements as well as more functional tasks such as simulated drinking from a glass

This study has two distinct aims to be addressed in a longitudinal study spanning 24 days.

Aim 1 tests the hypothesis that stroke survivors can improve motor control of their contralesional arm through extended training with supplemental kinesthetic feedback applied to the non-moving arm and hand.

Aim 2 tests the hypothesis that extended training with supplemental kinesthetic feedback can lead to new skills that generalize to untrained reach-to-grasp actions like reaching for a water glass or a book on a shelf.

Day 1: Participants complete baseline tests of cognitive performance over several domains, including psychomotor speed (e.g., Symbol Digit Modalities Test; Digit Copy Test), memory (Rey Auditory Verbal Learning Test; Rey Osterrieth Complex Figure Test), cognitive flexibility/attention shifting (Trail-Making Test B; Wisconsin Card Sort Test), spatial processing (Rey Osterrieth Complex Figure copy test), and action selection/inhibition. (the go, no-go, and stop signal tests).

Day 2: Participants complete baseline tests of sensorimotor impairment and function. Tests of sensorimotor impairment include the upper extremity Fugl-Meyer Assessment for the contralesional arm, two-point discrimination, vibration sensation using a 128 Hz tuning fork, and a robotic test of proprioception in both arms. Motor function in the contralesional arm will be assessed using the Jamar grip strength assessment and the Wolf Motor Function Test.

Day 3: We will test the subjects on their naïve capability to use a 3-Degree-Of-Freedom (3-DOF) vibrotactile display to guide supported (but unconstrained) 3D movements mimicking reach-to-grasp actions like reaching for a water glass or a book on a shelf. The vibrotactile display will provide supplemental kinesthetic feedback of limb movement.

Days 4-23: These 20 sessions train participants on the use of of supplemental kinesthetic feedback of limb movement. We will test two groups of 15 stroke survivors each. Subjects will use supplemental vibrotactile feedback to guide goal-directed reach-to-grasp movements to targets presented visually in 3D space. Individuals assigned to the PROGRESSIVE TRAINING group will practice for several days on interpreting feedback along just one dimension of movement before training to interpret 2 dimensions of feedback. they will conclude training by training to interpret 3D vibrotactile feedback. Individuals assigned to the 3D TRAINING group will only train on the full 3D feedback system.

Day 24: We will re-test the subjects on their capability to use a 3-DOF vibrotactile display to guide supported (but unconstrained) 3D movements mimicking reach-to-grasp actions like reaching for a water glass or a book on a shelf.

Eligibility Criteria:
Inclusion Criteria:

* stroke survivors who can perform our stabilization and grip modulation tasks and who
* had a single ischemic or hemorrhagic stroke of the middle cerebral artery (MCA) in the chronic state of recovery (\> 6 months post-stroke).
* ability to give informed consent and be able to follow two-stage instructions.
* mild-to-moderate motor impairment as assessed using the upper extremity (UE) portion of the Fugl-Meyer Motor Assessment (FM); i.e., UE-FM score between 28 and 50 (inclusive) out of a possible 66.
* proprioceptive deficit at the elbow in the more involved (contralesional) arm.
* preserved tactile sensation in either the ipsilesional arm and/or thigh.
* a minimal active wrist extension of 5°.

Exclusion Criteria:

* Inability of subjects to give informed consent or follow two-stage instructions.
* subjects with a bleeding disorder.
* subjects with fixed contractures or a history of tendon transfer in the involved limb.
* subjects with a diagnosis of myasthenia gravis, amyotrophic lateral sclerosis or any disease that might interfere with neuromuscular function.
* subjects who are currently using or under the influence of aminoglycoside antibiotics, curare-like agents, or other agents that may interfere with neuromuscular function.
* subjects with a history of epilepsy.
* history of other psychiatric co-morbidities (e.g. schizophrenia).
* malignant or benign intra-axial neoplasms.
* concurrent illness limiting the capacity to conform to study requirements.
* Cardiac pacemaker, cardiac arrhythmia or history of significant cardiovascular or respiratory compromise.
* subjects with profound atrophy or excessive weakness of muscles in the target area(s) of testing.
* subjects with a systemic infection.