Prefrontal and sensorimotor cortices showed opposite patterns of hemodynamic activity changes between eyes-open and eyes-closed conditions in blepharospasm

Background Blepharospasm (BSP), characterized by involuntary eyelid closure and difficulty opening the eyes, often results in functional blindness. However, there is a lack of objective and quantitative diagnostic markers, and the differences in hemodynamics between eyes-open (EO) and eyes-closed (EC) conditions are unknown in BSP. Objective To address this issue, we utilized functional near-infrared spectroscopy (fNIRS) to measure the oxygenation differences in the prefrontal cortex (PFC) and sensorimotor cortex in response to EO and EC conditions and compared them with those of healthy controls. Methods We analyzed data from 96 BSP individuals and 31 healthy controls (HCs) by using the amplitude of low-frequency fluctuations (ALFF) determined by functional near-infrared spectroscopy (derived from fNIRS) to measure the oxygenation differences in the prefrontal cortex (PFC) and sensorimotor cortex in response to EO and EC conditions. Results The BSP group and the HC group exhibited opposite patterns of differences between the EC and EO conditions. In the HC group, the ALFF was greater in the EC condition than in the EO condition in the frontopolar area (FPA) and orbitofrontal cortex and lower in the EC condition than in the EO condition in the bilateral sensorimotor cortex. In the BSP group, the ALFF was greater in the EC condition than the EO condition in the bilateral sensorimotor cortex and lower in the EC condition than in the EO condition in the frontopolar area and bilateral dorsolateral prefrontal cortex. Moreover, differences in the EC-EO patterns at channel 44 and channel 3 between the two groups showed promising excellent discrimination potential, pending external validation. Conclusion The BSP group and the HCs group showed opposite patterns of EO-EC differences in the prefrontal cortex and sensorimotor cortex. The delta EO-EC difference between the right S2 and the right FPA showed promising has excellent differential diagnostic value for BSP in this discovery cohort and is a candidate and is expected to become an early diagnostic biomarker requiring external validation and neuromodulation therapeutic target.