Effects of Dualsite Anodic tDCS on Lower Limbs Function in Patients After Stroke: Randomized, Double-blind, Placebo-controlled, Crossover Trial

It is currently known that Transcranial Direct Current Stimulation (tDCS) can modulate cortical activity, being considered an important resource in the treatment of sequelae resulting from stroke. However, evidence of the effects of tDCS on lower limb motor recovery after stroke remains scarce and inconclusive. Furthermore, little is known about the effects of dualsite tDCS in chronic patients. Therefore, the present study seeks to compare the effects of conventional anodic tDCS (M1) with double-site/dualsite anodic tDCS (M1 + DLPFC) and simulated tDCS on lower limb motor function in patients after ischemic stroke in a chronic stage. The study is a randomized, double-blind, placebo-controlled, crossover clinical trial with subjects after stroke. After recruitment and initial screening, participants will be randomized into three groups: G1: anodic tDCS - participants who will receive real current over the primary motor area; G2: dualsite tDCS - participants who will receive real current over the primary motor area and dorsolateral prefrontal area (DLPFC) and G3: simulated tDCS - participants who will receive simulated stimulation. Participants will receive 10 tDCS sessions, for 20 minutes, associated with a physical therapy protocol based on a dual motor and cognitive task, on alternate days (3 times a week). In each phase of the study, pre- and post-intervention evaluations will be carried out, the evaluated outcomes will be: motor function (Fugl-Meyer Scale), functional connectivity (EEG), quality of life (EQ-5D), level of functional disability ( Rankin Scale), static balance (Biodex Balance System) and cognitive function (MoCA). Statistical analyzes will be performed using SPSS software (Version 20.0) and MATLAB 9.2.0 with a significance level of p \<0.05.

Participants will be divided into 03 groups: G1: anodic tDCS - participants who will receive real current over the primary motor area; G2: dualsite tDCS - participants who will receive real current over the primary motor area and over the dorsolateral prefrontal area (DLPFC) and G3: simulated tDCS - participants who will receive simulated stimulation. Participants will be entered into the study through the eligibility criteria and will be randomly allocated, with block exchange at a rate of 1:1:1.

In each phase of the study, participants will receive 10 tDCS sessions, for 20 minutes, on alternate days (3 times a week, excluding weekends). The TCT-Research neurostimulator will be used for stimulation. The electrodes will be positioned according to the 10-20 international electroencephalogram classification system. Electrodes wrapped in sponges, moistened with saline solution (0.9% NaCl) will be used. The applied current will be 2mA (5x5 cm active electrodes; 25 cm2; current density of 0.08 mA/cm2).

For group 1 (anodic tDCS) the anodic electrode (5x5 cm) will be applied to the primary motor area (C3/C4) ipsilateral to the lesion and the reference electrode (6x9 cm) to the deltoid muscle region. In group 2 (dualsite tDCS) two active electrodes (5x5 cm) will be used, which will be positioned over the primary motor area (C3/C4) and over the dorsolateral prefrontal cortex (F3 or F4) in the ipsilateral hemisphere. For this stimulation modality, two active electrodes (anodic) and a reference electrode (6x9 cm) will be used on the deltoid muscle region.

For group 3 (simulated tDCS) the positioning of the electrodes will be the same as for group 1, however the device will be configured in sham mode in which the current will cease 30 seconds after the start of stimulation, in this way the effects of active stimulation will be simulated and the participants will perceive the sensations typically felt, but without the induction of clinical effects (Nitsche \& Paulus, 2000). At the end of each session, participants will be asked to report any unpleasant effects and asked about possible adverse effects. In addition, all participants will be blind to the type of stimulation they will receive.

Eligibility Criteria:
Inclusion Criteria:

* Single episode of unilateral, ischemic stroke in middle cerebral artery proven by means of magnetic resonance imaging or computed tomography.
* Classification of brain injury based on the criteria: Oxfordshire Community Stroke Project (OCSP) or Trial of Org 10172 in Acute Stroke Treatment (TOAST);
* Patients in the chronic stage (after six months after the injury)
* Individuals over 18 years of age;
* Both sexes;
* Absence of mental disorders, assessed using the Self Reporting Questionnaire (SRQ-20), with a cut-off point of 7/8 points.
* Absence of cognitive deficits, assessed using the Mini Mental State Examination (MMSE\> 24).
* Patients with mild to moderate degree of injury severity (NIHHS \<17 points).

Exclusion Criteria:

* Patients with other associated pathologies that can influence motor activity (example: traumatic brain injury, brain tumor);

  •- Participants unable to complete the initial assessment due to severe aphasia (Token Test \<17);
* habitual use of drugs or alcohol;
* Use of drugs that modulate the activity of the Central Nervous System;
* Gestation;
* Use of metallic / electronic implants and / or cardiac pacemakers;