Exploring the relationship between prefrontal cortex activation, standing balance, and fatigue in people post-stroke: A fNIRS study

BackgroundBalance impairments and fatigue are common after stroke and impact physical therapy assessments and treatments. Reasons are multifactorial and include motor dysfunction and changes to cortical activation poststroke. The prefrontal cortex (PFC) is involved in motor control; yet, limited research has explored cortical activation during common physical therapy balance tasks or the link with fatigue.ObjectivesDuring standing balance tasks, the objective was to determine whether PFC activation levels: (1) change between tasks, (2) are asymmetric, and (3) are associated with fatigue.MethodsPatients with hemiparesis were recruited from an inpatient stroke unit and functional near-infrared spectroscopy was applied bilaterally over the PFC to measure cortical activation during balance tasks. Fatigue was assessed using the Fatigue Severity Scale (FSS).ResultsNine participants were included. PFC activation during semi-tandem stance showed greater amplitude than during double-leg stance, indicating more cortical activation. Bilateral PFC activation was observed during both tasks. Participants with greater fatigue (higher FSS score) showed more activation in the ipsilesional PFC than the contralesional PFC.ConclusionPFC activation may occur when performing more challenging balance postures, potentially indicating compensatory activation, and may be linked with greater fatigue.