Understanding neural mechanisms and the use of targeted non-invasive brain stimulation for treatment of post-stroke fatigue: A scoping review.

BACKGROUND

Post-stroke fatigue (PSF) is one of the most prevalent symptoms that affects quality of life and daily function after stroke. Despite a growing body of research, its pathophysiology is poorly understood. Non-invasive brain stimulation (NIBS), such as the transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can serve as a non-pharmacological intervention for PSF. In this review, we aim to (1) evaluate PSF neuroimaging studies to deduce potential neural mechanisms, (2) describe NIBS as a tool to probe brain structures to further understand pathophysiology of fatigue, and (3) assess NIBS as a treatment intervention for PSF.

METHODS

A systematic search was conducted for the databases PubMed, Embase, Scopus, CINAHL and Cochrane. Studies were included based on the following inclusion and exclusion criteria: >18 years with PSF, use of neuroimaging and/or NIBS for investigation or as an intervention for PSF, English language, study types including cohort, case control, or randomized controlled trials. Data extracted included participant characteristics, concept, context, study methods, and key findings relevant to the review questions.

RESULTS

A total of 30 studies met criteria. Neuroimaging papers that investigated brain structure (MRI) found conflicting associations between lesion location and PSF. Functional methods (fMRI, TMS) revealed altered resting state functional connectivity (rsFC), cortical excitability, and a disruption in interhemispheric inhibitory balance as potential mechanisms of PSF. There were no studies using TMS as an intervention for PSF. Of the six articles that used tDCS, only two reported statistically significant reductions in the severity of PSF.

CONCLUSION

Structural characteristics of stroke lesions had conflicting findings, while functional neuroimaging studies suggested that altered rsFC, cortical excitability and interhemispheric inhibitory balance contribute to the development of PSF. There were inconsistent results on the effectiveness of tDCS as an intervention for PSF, due to varying methodologies and lack of precise targeting of underlying neural mechanisms. Further investigations are needed to determine if NIBS could be a potential treatment to alleviate the effects of PSF.