A review about synergistic effects of transcranial direct current stimulation (tDCS) in combination with motor imagery (MI)-based brain computer interface (BCI) on post-stroke rehabilitation

Purpose: The purpose of this study is to determine if the application of combined forms of tDCS and BCIs based on motor imagery (MI) through electroencephalography (EEG) can synergistically enhance the process of rehabilitation in stroke survivors. Additionally, a discussion is conducted about the issues of BCI maladaptation, as well as the lack of use of BCIs in post-stroke rehabilitation processes, concluding about the importance of using tDCS as a solution for this issue. Finally, we propose two different stroke rehabilitation protocols using cerebro-cerebellar transcranial direct current stimulation (ctDCS) and transcutaneous spinal direct current stimulation (tsDCS) in combination with the MI-based BCI. Method: This review of literature explores findings of studies conducted in the last 10 years (2012–2022) about applications of tDCS combined with EEG-based MI-BCIs in stroke patients and healthy subjects. Results: The main characteristic of methods used in the revised studies differs among them, resulting in heterogeneous data that makes systematic analysis difficult. Although it has been challenging the comparison among the different studies, due to the lack of a standardized intervention protocol, interesting common features have been identified, such as classification accuracy of MI, laterality coefficient (LC), event-related desynchronization (ERD), functional connectivity (FC) of brain, and Fugl-Meyer assessment (FMA). Conclusion: Despite this heterogeneity of results, the revised studies from the literature confirm the synergistic effects of tDCS to improve MI-based BCIs in neurorehabilitation processes for post-stroke patients. © The Author(s), under exclusive licence to The Brazilian Society of Biomedical Engineering 2023.