Changes in EEG Microestates After Combined Treatment od Tdcs and Dual-task Training in Stroke Patients: a Cross-roads, Sham-controlled,Double-blind Clinical Trial

Cerebrovascular Accident (CVA) has been considered one of the main causes of long-term disability in the adult population. Stroke usually causes deficits such as asymmetrical muscle weakness between limbs, impaired proprioceptive ability, sensory loss, vision problems, and spasticity. In post-stroke patients, it is believed that the interhemispheric balance may be altered as a result of brain injury, the theory of interhemispheric competition is widely used as a theoretical basis for the application of non-invasive neuromodulatory techniques. Technological advances in the neurological field have been seen in recent decades, which accentuates the interest in promoting non-invasive stimulation techniques, capable of modulating brain polarity, where among these techniques is transcranial direct current stimulation - tDCS. Previous studies analyzed by systematic reviews suggest that the effects of tDCS may vary between subjects, where some stroke patients may not receive any additional benefit from the therapy. Thus, it is necessary to use a biomarker that can choose those who will possibly benefit from the electric current. Therefore, the aim of this study is to identify the dynamics of EEG microstates after tDCS and dual-task training in subjects after chronic stroke, as well as to assess how microstate parameters in stroke patients are altered by tDCS and dual-task training at three different times (Stimulation in M1 + dual-task training; Stimulation in M1 and DLPF + dual-task training; Sham stimulation) and observe whether the microstates encode information that reflects the motor and/or cognitive capacity of these patients. For this, a clinical trial, sham-controlled, double-blind and randomized, of crossover type, involving patients with stroke in chronic stage will be carried out. Participants will be submitted to three sessions, each session consisting of a different condition, namely: first condition (anodic tDCS) participants will receive real current over the primary motor area (M1); second condition (dualsite tDCS) participants will receive real current over M1 and dorsolateral prefrontal area (DLPFC) and third condition (sham tDCS) participants will receive simulated stimulation. A 3-minute resting EEG will be collected from each participant, and they will be instructed not to actively engage in any cognitive or mental activity. In all stimulation sessions, evaluations will be carried out, the evaluated outcomes will be: change in EEG microstates, cognitive function and motor function. Statistical analyzes will be performed using SPSS software (Statistical Package for Social Sciences - SPSS Inc, Chicago IL, USA for Windows, Version 20.0) and MATLAB (9.2.0 (MathWorks, Inc., Natick, MA) with a defined level of significance at p<0.05.