Neural effective connectivity explains subjective fatigue in stroke.

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Persistent fatigue is a common and debilitating symptom following stroke.
• The underlying neural mechanisms of post-stroke fatigue, particularly its chronicity and link to motor cortex excitability, remain unclear.

Purpose of the Study:

• To investigate the relationship between neuronal effective connectivity and self-reported fatigue in non-depressed stroke survivors.
• To identify neural mechanisms contributing to persistent fatigue after stroke.

Main Methods:

• Cross-sectional observational study involving 59 stroke survivors with minimal motor/cognitive impairments.
• Utilized resting-state MRI, single- and paired-pulse transcranial magnetic stimulation (TMS).
• Assessed inter-hemispheric inhibition balance using TMS and fatigue levels via the Fatigue Severity Scale (FSS-7).

Main Results:

• A novel index of inter-hemispheric inhibition balance significantly predicted post-stroke fatigue in both experiments.
• In Experiment 2, depression scores and corticospinal excitability also contributed to fatigue variability.
• Findings suggest that the balance of inhibitory effects between homologous primary motor regions is a key factor in post-stroke fatigue.

Conclusions:

• The balance in inter-hemispheric inhibitory effects between primary motor regions is a significant predictor of subjective post-stroke fatigue.
• This study offers novel insights into the neural underpinnings of persistent fatigue after stroke.
• Understanding these mechanisms may inform future therapeutic strategies for managing post-stroke fatigue.