Changes in cerebral motor cortex hemodynamics in stroke patients with limb motor dysfunction under different states: a functional near-infrared spectroscopy study

Abstract Background Motor dysfunction after stroke is closely associated with hemodynamic alterations in the motor cortex. Functional near-infrared spectroscopy (fNIRS) enables non-invasive monitoring of dynamic changes in cortical oxygenated hemoglobin (HbO) concentration, providing an objective means for assessing post-stroke cortical reorganization. This study aimed to compare motor-cortex hemodynamic responses between stroke patients and healthy controls under resting and motor-task conditions using fNIRS, and to identify sensitive indicators reflecting post-stroke cortical functional status. Methods A total of 36 stroke patients and 20 healthy controls were recruited. fNIRS was used to record HbO signals from the motor cortex during resting state and a shoulder-touching task. Three metrics were extracted: mean HbO concentration, peak HbO concentration, and time-to-peak (TTP). A two-way mixed-design ANOVA (Group × Task Type) was performed to compare the two groups across all metrics. Significant main effects and interactions were followed by simple effects analyses and post hoc pairwise comparisons with Bonferroni correction. Results Stroke patients exhibited significantly lower resting-state mean HbO concentrations than healthy controls ( p = 0.024), but reached comparable levels during task performance ( p = 0.242). Within-group comparisons revealed no significant task-evoked changes in any metric in healthy controls (all p > 0.05), whereas stroke patients showed significant task-evoked increases in all three metrics (all p < 0.001). Significant Group × Task interactions were observed for all three metrics (mean HbO: p = 0.012; peak HbO: p = 0.026; TTP: p < 0.001). TTP showed the strongest interaction, with a striking reversal between groups: stroke patients had shorter TTP than healthy controls at rest ( p < 0.05) but significantly prolonged TTP during task ( p < 0.01). Conclusions Stroke patients exhibit a “magnitude compensation with temporal impairment” hemodynamic response pattern in the motor cortex. Time-to-peak, as a temporal metric reflecting neurovascular coupling efficiency, may serve as a potential indicator for assessing cerebral blood flow regulation after stroke and warrants further validation in larger longitudinal studies.