Augmentation of Locomotor Adaptation Post-Stroke

Study Overview
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Brief Summary
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This project will evaluate two different methods of normalizing the center of mass acceleration (COMa) in individuals post-stroke, specifically focusing on rates and pattern of recovery to analyze walking-specific adaptations as precursors to motor learning. In addition, the proposed project seeks to establish the optimal configuration of electrodes to activate neural circuits involved in post-stroke locomotion. Once the better method of training COMa and optimal parameters of electrode placement for tDCS are identified, the investigators will evaluate the effects of tDCS on locomotor adaptations during single sessions and over a five-day training period.

Detailed Description
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The project seeks to establish the optimal configuration of electrodes to change the excitability of neural circuits involved in post-stroke locomotion, identify effective strategies for training a specific locomotor adaptation, and improve adaptations via adjunctive non-invasive brain stimulation. Tools to improve neural excitability may increase potential for locomotor skill learning, thereby improving rehabilitation outcomes. Non-invasive brain stimulation with transcranial direct current stimulation (tDCS) has recently emerged as a simple to administer, low-cost, and low-risk option for stimulating brain tissue. Cortical excitability is increased after application and preliminary results imply a relationship to increases in motor activity in those post-stroke. However, inhibition of the contralesional hemisphere is also shown to improve paretic motor output through inhibition of excessive maladaptive strategies, and combining the two electrode configurations may provide additional benefit for locomotor tasks requiring interlimb coordination. Furthermore, the effects of tDCS on walking function in conjunction with physical intervention strategies aimed at improving locomotor ability post-stroke are yet unstudied.

Official Title
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Augmentation of Locomotor Adaptation Post-Stroke

Conditions
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Stroke

Intervention / Treatment
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* Device: tDCS
* Device: Sham tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Chronic Stroke age 18-70 at least six month post-stroke residual paresis in the lower extremity (Fugl-Meyer LE motor score <34) ability to sit unsupported for ≥ 30 sec ability to walk at least 10 ft. self-selected 10 meter gait speed < 0.8 m/s provision of informed consent. Exclusion Criteria: Acute Stroke Unable to ambulate at least 150 feet prior to stroke, or experienced intermittent claudication while walking < 200 meters history of congestive heart failure, unstable cardiac arrhythmias, hypertrophic cardiomyopathy, severe aortic stenosis, angina or dyspnea at rest or during activities of daily living History of COPD or oxygen dependence Preexisting neurological disorders, dementia or previous stroke History of major head trauma Legal blindness or severe visual impairment history of significant psychiatric illness Life expectancy <1 yr Severe arthritis or orthopedic problems that limit passive ROM post-stroke depression (PHQ-9 ≥10) History of DVT or pulmonary embolism within 6 months Uncontrolled diabetes with recent weight loss, diabetic coma, or frequent insulin reactions Severe hypertension with systolic >200 mmHg and diastolic >110 mmHg at rest presence of cerebellar stroke.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Uphill COMa training<br>Walking on an inclined treadmill, thus manipulating the permissive environment to elicit COMa adaptation, while receiving either tDCS or sham tDCS. | Device: tDCS<br>* Constant non-invasive, low intensity, direct electrical current utilized to stimulate specific areas of the brain. Evaluating immediate effects of anodal/cathodal stimulation during 20 minutes of treadmill walking.<br>Device: Sham tDCS<br>* Per published protocols, tDCS will be administered for 30 secs allowing for sensory adaptation to occur and then turned off, so that the remaining sham stimulation will include zero current. Evaluating immediate effects during 20 minutes walking on a treadmill.<br>|
| Experimental: Downhill COMa training<br>Walking on a declined treadmill, thus manipulating the permissive environment to elicit COMa adaptation, while receiving either tDCS or sham tDCS. | Device: tDCS<br>* Constant non-invasive, low intensity, direct electrical current utilized to stimulate specific areas of the brain. Evaluating immediate effects of anodal/cathodal stimulation during 20 minutes of treadmill walking.<br>Device: Sham tDCS<br>* Per published protocols, tDCS will be administered for 30 secs allowing for sensory adaptation to occur and then turned off, so that the remaining sham stimulation will include zero current. Evaluating immediate effects during 20 minutes walking on a treadmill.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Center of Mass Acceleration Peak | Peak full body center of mass acceleration during gait, expressed as m/sec^2, captured during 30 seconds of treadmill walking at a steady-state, self-selected walking speed. | Pre (same as initial session) and post (immediately following final session) conducted within 5-10 days apart according to subject availability. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Center of Mass Acceleration Impulse | Positive integral of the full body center of mass acceleration during the gait cycle, expressed as an average over all strides captured during 30 seconds of data collection at a steady-state, self-selected walking speed (m/sec). | Pre (directly prior to initial session) and post (immediately following final session) conducted within 5-10 days apart according to subject availability. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Chronic Stroke ( > 6 months), non-invasive brain stimulation, rehabilitation, walking, kinetics