Targeted High-definition Transcranial Direct Current Stimulation (HD-tDCS) for Reducing Post-stroke Movement Impairments

Study Overview
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Brief Summary
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Stroke is the leading cause of serious, long-term disability. The emergence of abnormal muscle synergies following a stroke presents a major limitation to the recovery of independent function. Despite the development of many interventions for movement recovery post-stroke, rehabilitation treatments are minimally effective to the muscle synergy impairment. Previous studies have found that muscle synergy impairment is associated with the damage to the corticospinal tract and the maladaptive recruitment of the contralesional cortico-reticulospinal tract. The investigators hypothesize that facilitating the damaged cortico-spinal tract (via primary motor cortex) and/or inhibiting the contralesional cortico-reticulospinal tract (via dorsal premotor cortex) will reduce muscle synergy impairment. In this pilot project, the investigators propose to run a proof-of-concept pilot trial to evaluate the effect of the targeted high-definition transcranial direct current stimulation (HD-tDCS) on mitigating muscle synergy impairment.

Detailed Description
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This randomized, double-blinded, sham-controlled cross-over study will include three stimulation conditions: 1) anodal stimulation over the ipsilesional primary motor cortex, 2) cathodal one over the contralesional premotor cortex, 3) sham stimulation in chronic hemiparetic stroke patients. Stroke participants (> 3 months after stroke) with moderate to severe motor impairments (Fugl-Meyer Motor Assessment - Upper Extremity score between 10-40, in absence of clinically defined sensory deficits) and an ischemic unilateral subcortical lesion will receive each type of stimulation for 20 minutes. Their brain activity and behavior data will be collected for the outcome measures. The patient time commitment in this study is approximately 7 weeks where subjects have 3 x 1-day intervention and measurements, with 2 weeks washout period in between. The total number of potential enrolled subjects in this pilot study is 12.

Official Title
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Targeted HD-tDCS for Reducing Post-stroke Movement Impairments

Conditions
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Stroke

Intervention / Treatment
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* Device: Transcranial direct current stimulation (high-definition)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ischemic unilateral stroke lesion (confirmed by the most recent clinical or radiological reports) at least 3 months prior to participation in this project. Paresis confined to one side, with moderate to severe motor impairment of the upper limb (Fugl-Meyer upper extremity scores of 10-40) Capacity to provide informed consent Exclusion Criteria: Muscle tone abnormalities and motor or sensory impairment in the unimpaired limb Severe wasting or contracture or significant sensory deficits in the paretic upper limb Severe cognitive or affective dysfunction that prevents normal communication and understanding of consent or instruction Severe concurrent medical problems (e.g. cardiorespiratory impairment) Using a pacemaker Metal implants in the head Known adverse reaction to TMS and tDCS Pregnant

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: This sham-controlled cross-over study design will include three visits: 1) anodal stimulation targeting ipsilesional primary motor cortex, 2) cathodal one at the contralesional premotor cortex, 3) a sham stimulation visit. The sequence of the stimulations will be randomized and double-blinded. After each intervention, there will be at least 2 weeks wash-out period before participants receive the next intervention and assessments.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Anodal stimulation<br>Anodal stimulation targeting hemisphere | Device: Transcranial direct current stimulation (high-definition)<br>* Three conditions: anodal stimulation over the ipsilesional primary motor cortex cathodal one over the contralesional premotor cortex Sham<br>|
| Experimental: Cathodal stimulation<br>Cathodal one at the contralesional hemisphere | Device: Transcranial direct current stimulation (high-definition)<br>* Three conditions: anodal stimulation over the ipsilesional primary motor cortex cathodal one over the contralesional premotor cortex Sham<br>|
| Experimental: Sham stimulation<br>Sham stimulation to the brain | Device: Transcranial direct current stimulation (high-definition)<br>* Three conditions: anodal stimulation over the ipsilesional primary motor cortex cathodal one over the contralesional premotor cortex Sham<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in a subset of Fugl-Meyer Upper Extremity assessment which is mainly related to the muscle synergies | This measure determines the expression of the muscle synergy impairment after a stroke | Baseline (initial visit), before (within 30 min range) and immediately after (within 30 min range) the intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Transcranial magnetic stimulation (TMS)-evoke motor-evoked potentials (MEP) | This is a neurophysiological measure that determines the use of ipsilesional corticospinal tract and the contralesional cortico-reticulospinal tract. | Baseline (initial visit), before (within 30 min range) and immediately after (within 30 mins range) the intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Stroke, HD-tDCS, upper limb impairment