Task-state hemodynamic responses correlate with consciousness levels and outcomes of patients with disorders of consciousness

Background: Functional near-infrared spectroscopy (fNIRS) has emerged as a valuable tool for detecting brain functional activities. Motor imagery (MI) tasks have been employed to evoke brain responses in patients with disorders of consciousness (DOC), providing potential insights into their consciousness levels. However, the utility of brain functional characteristics for patient diagnosis and prognosis remains unclear. Objective: This study aims to use fNIRS to investigate the characteristics of brain functional activities evoked by MI task in populations with varying levels of consciousness, and to explore the potential of these characteristics in the diagnosis and prognosis of DOC. Methods: fNIRS was used to measure hemodynamic responses during MI tasks in a cohort of 63 DOC patients (26 vegetative states [VS] and 37 minimally conscious states [MCS]) and 70 healthy controls (HC). The mean values of hemodynamic responses in each brain region were extracted for inter-group and intra-group comparisons. Additionally, the correlation between hemodynamic responses and prognosis of DOC patients was investigated. Results: Inter-group comparisons revealed that HC had significantly higher hemodynamic responses than both the MCS and VS groups across all brain regions. The MCS group demonstrated significantly higher responses than the VS group in the left premotor cortex, left primary motor cortex, right primary motor cortex, and left parietal cortex. In intra-group comparisons, 33 and 7 pairs of brain regions were significantly different in the HC and MCS group, while no significant differences were observed in the VS group. Furthermore, a significant correlation was found between the hemodynamic responses and the prognosis scores of DOC patients 6 months after the fNIRS examination. Conclusions: Task-evoked functional activities in various brain regions among populations with varying levels of consciousness demonstrate significant intra-group and inter-group differences. The characteristics of brain functional activities provide valuable insights for the diagnosis and prognosis of DOC patients.