Background
Aphasia is an acquired language impairment that commonly results from stroke. Non-invasive brain stimulation (NIBS) might accelerate aphasia recovery trajectories and has seen mounting popularity in recent aphasia rehabilitation research. The present review aimed to: 1) summarise all existing literature on NIBS as a post-stroke aphasia treatment; and 2) provide recommendations for future NIBS-aphasia research.
Methods
Databases for published and grey literature were searched using scoping review methodology. 278 journal articles, conference abstracts/posters, and books, and 38 items of grey literature, were included for analysis.
Results
Quantitative analysis revealed that ipsilesional anodal transcranial direct current stimulation and contralesional 1-Hz repetitive transcranial magnetic stimulation were the most widely used forms of NIBS, while qualitative analysis identified four key themes including: the roles of the hemispheres in aphasia recovery and their relationship with NIBS; heterogeneity of individuals and homogeneity of subpopulations; individualisation of stimulation parameters; and the unknown of NIBS.
Conclusion
Taken together, results from quantitative and qualitative analysis highlighted systemic challenges across the field such as small sample sizes, inter-individual variability, lack of protocol optimisation/standardisation, and inadequate focus on aphasiology. Four key recommendations are outlined to guide future research and refine NIBS methods for post-stroke aphasia treatment.