A resting-state functional MRI study on the effect of vagal nerve stimulation on spontaneous regional brain activity in drug-resistant epilepsy patients

Abstract

PurposeTo explore the effect of vagal nerve stimulation (VNS) on spontaneous brain activity in patients with drug-resistant epilepsy (DRE). Methods15 patients and eight healthy controls (HC) were enrolled and scanned by resting-state functional MRI to investigate changes in the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo). A two-sample t-test or paired sample t-test was used to compare activity between the HCs, preoperative patients (EP-pre), and postoperative patients (EP-post). We also performed correlation analyses to examine the seizure improvement ratio. ResultsThe voxel-level analyses indicated that, compared with the HC, the EP-pre group exhibited decreased or increased fALFF and ReHo in the frontal cortex, temporal cortex, precentral/postcentral gyrus, amygdala, insula, cerebellum, and lingual gyrus. Furthermore, compared with the EP-pre group, the EP-post group exhibited decreased or increased fALFF and ReHo in the frontal cortex, temporal cortex, precentral gyrus, insula, anterior/median cingulate gyri, and cerebellum. The regions of interest-level analyses indicated that, compared with HC, the EP-pre group exhibited decreased fALFF or ReHo in the caudate nucleus, supramarginal gyrus, precuneus and middle temporal gyrus. Furthermore, compared with the EP-pre group, the EP-post group exhibited increased fALFF or ReHo in the olfactory cortex, gyrus rectus, and superior temporal gyrus. Increased ReHo in the right superior or middle temporal gyrus was positively correlated with the improvement ratio. ConclusionsAltered regional activity in DRE patients was reorganized after 3 months of stimulation. Increased ReHo in the right superior or middle temporal gyrus was implicated in VNS-induced improvement in seizure frequency.