Post-stroke fatigue: a deficit in corticomotor excitability?

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Clinical Neurology

Background:

• Post-stroke fatigue is a common and debilitating symptom.
• Its underlying pathophysiology, particularly non-exercise-related fatigue, remains poorly understood.
• Central nervous system dysfunction is implicated in its development.

Purpose of the Study:

• To investigate the relationship between corticomotor excitability and self-reported fatigue in chronic stroke survivors.
• To explore neurophysiological correlates of fatigue and perceived effort post-stroke.

Main Methods:

• Cross-sectional observational study of 70 first-time stroke survivors with minimal motor/cognitive impairment.
• Fatigue assessed using Fatigue Severity Scale 7 and Neurological Fatigue Index - Stroke.
• Corticomotor excitability measured via transcranial magnetic stimulation (TMS), including motor thresholds and paired pulse paradigms.
• Central activation failure assessed using a modified twitch interpolation technique.

Main Results:

• Resting motor threshold significantly predicted variance in Fatigue Severity Scale 7 scores (14.7% variance explained).
• Central activation failure significantly predicted perceived effort scores (17.3% variance explained).
• Higher fatigue correlated with higher motor thresholds; higher perceived effort correlated with lower neural input excitability.

Conclusions:

• Reduced corticospinal excitability and impaired facilitatory synaptic input to the motor cortex may contribute to fatigue after stroke.
• These findings suggest potential neurophysiological targets for managing post-stroke fatigue.