Prior physical exertion modulates allocentric distance perception: a demonstration of task-irrelevant cross-modal transfer

Effect of transcranial direct current stimulation on post-stroke fatigue

Background

Fatigue is one of the most commonly reported symptoms post-stroke, which has a severe impact on the quality of life. Post-stroke fatigue is associated with reduced motor cortical excitability, specifically of the affected hemisphere.

Objective

The aim of this exploratory study was to assess whether fatigue symptoms can be reduced by increasing cortical excitability using anodal transcranial direct current stimulation (tDCS).

Methods

In this sham-controlled, double-blind intervention study, tDCS was applied bilaterally over the primary motor cortex in a single session in thirty stroke survivors with high severity of fatigue. A questionnaire-based measure of trait fatigue (primary outcome) was obtained before, after a week and 5 weeks post stimulation. Secondary outcome measures of state fatigue, motor cortex neurophysiology and perceived effort were also assessed pre, immediately post, a week and 5 weeks post stimulation.

Results

Anodal tDCS significantly improved fatigue symptoms a week after real stimulation when compared to sham stimulation. There was also a significant change in motor cortex neurophysiology of the affected hemisphere and perceived effort, a week after stimulation. The degree of improvement in fatigue was associated with baseline anxiety levels.

Conclusion

A single session of anodal tDCS improves fatigue symptoms with the effect lasting up to a week post stimulation. tDCS may therefore be a useful tool for managing fatigue symptoms post-stroke.

Trial registration

NCT04634864

Date of registration

17/11/2020–“retrospectively registered”.

Exploring the relationship between effort perception and poststroke fatigue

OBJECTIVE

To test the hypothesis that poststroke fatigue, a chronic, pathologic fatigue condition, is driven by altered effort perception.

METHODS

Fifty-eight nondepressed, mildly impaired stroke survivors with varying severity of fatigue completed the study. Self-reported fatigue (trait and state), perceived effort (PE; explicit and implicit), and motor performance were measured in a handgrip task. Trait fatigue was measured with the Fatigue Severity Scale-7 and Neurologic Fatigue Index. State fatigue was measured with a visual analog scale (VAS). Length of hold at target force, overshoot above target force, and force variability in handgrip task were measures of motor performance. PE was measured with a VAS (explicit PE) and line length estimation, a novel implicit measure of PE.

RESULTS

Regression analysis showed that 11.6% of variance in trait fatigue was explained by implicit PE (R = 0.34; p = 0.012). Greater fatigue was related to longer length of hold at target force (R = 0.421, p < 0.001). A backward regression showed that length of hold explained explicit PE in the 20% force condition (R = 0.306, p = 0.021) and length of hold and overshoot above target force explained explicit PE in the 40% (R = 0.399, p = 0.014 and 0.004) force condition. In the 60% force condition, greater explicit PE was explained by higher force variability (R = 0.315, p = 0.017). None of the correlations were significant for state fatigue.

CONCLUSION

Trait fatigue, but not state fatigue, correlating with measures of PE and motor performance, may suggest that altered perception may lead to high fatigue mediated by changes in motor performance. This finding furthers our mechanistic understanding of poststroke fatigue.