Non-invasive brain stimulation in the treatment of post-stroke aphasia: a scoping review

Abstract

Purpose

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.

Materials and 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 but homogeneity of subpopulations; individualisation of stimulation parameters; and much remains under-explored in the NIBS-aphasia literature.

Conclusions

Taken together, these results 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 herein to guide future research and refine NIBS methods for post-stroke aphasia treatment.

IMPLICATIONS FOR REHABILITATION

• A comprehensive review of non-invasive brain stimulation (NIBS) post-stroke aphasia literature, including all study designs, was required.

• Review of this literature revealed that anodal transcranial direct current stimulation is the mostly commonly used type of NIBS in aphasia treatment research.

• Systemic challenges across the field hinder prospective translation of NIBS into aphasia practice.

• Aphasia rehabilitation professionals should note that further research is required before NIBS is suitable for translation into clinical practice.

Keywords:

• Aphasia
• stroke
• non-invasive brain stimulation
• transcranial direct current stimulation
• transcranial magnetic stimulation
• repetitive transcranial magnetic stimulation
• rehabilitation

Disclosure statement

BH has a clinical partnership with Fourier Intelligence and a paid consultancy role with Recovery VR.

Additional information

Funding

This work was supported by the Australian Research Council Future Fellowships Grant (grant number: FT210100694) and the Australian Government Research Training Program Scholarship.