Assessment of synchronous neural activities revealed by regional homogeneity in individuals with acute eye pain: a resting-state functional magnetic resonance imaging study

Abstract

Objective: Previous neuroimaging studies have demonstrated that pain-related diseases are associated with brain function and anatomical abnormalities, whereas altered synchronous neural activity in acute eye pain (EP) patients has not been investigated. The purpose of this study was to explore whether or not synchronous neural activity changes were measured with the regional homogeneity (ReHo) method in acute EP patients.

Methods: A total of 20 patients (15 males and 5 females) with EP and 20 healthy controls (HCs) consisting of 15 and 5 age-, sex-, and education-matched males and females, respectively, underwent resting-state functional magnetic resonance imaging. The ReHo method was applied to assess synchronous neural activity changes.

Results: Compared with HCs, acute EP patients had significantly lower ReHo values in the left precentral/postcentral gyrus (Brodmann area [BA]3/4), right precentral/postcentral gyrus (BA3/4), and left middle frontal gyrus (BA6). In contrast, higher ReHo values in acute EP patients were observed in the left superior frontal gyrus (BA11), right inferior parietal lobule (BA39/40), and left precuneus (BA7). However, no relationship was found between the mean ReHo signal values of the different areas and clinical manifestations, which included both the duration and degree of pain in EP patients.

Conclusion: Our study highlighted that acute EP patients showed altered synchronous neural activities in many brain regions, including somatosensory regions. These findings might provide useful information for exploration of the neural mechanisms underlying acute EP.

Keywords: acute eye pain; corneal pain; functional magnetic resonance imaging; regional homogeneity; resting state.

Figure 1

Spontaneous brain activity in the EPs versus HCs. (A and B) Significant activity differences were observed in the left precentral/postcentral gyrus (BA3/4), right precentral/postcentral gyrus (BA3/4), left middle frontal gyrus (BA6), left superior frontal gyrus (BA11), right inferior parietal lobule (BA39/40), and left precuneus (BA7). The red or yellow denotes higher ReHo values, and the blue areas indicate lower ReHo values (P<0.01 for multiple comparisons using Gaussian Random Field theory (z>2.3, P<0.01, cluster >40 voxels, AlphaSim corrected corrected). (C) The mean values of altered ReHo values between the EPs and HC groups. Abbreviations: ReHo, regional homogeneity; EP, eye pain; HCs, healthy controls; PreCG/PosCG, precentral/postcentral gyrus; MFG, middle frontal gyrus; SFG, superior frontal gyrus; IPL, inferior parietal lobule; Precu, precuneus; L, left; R, right; BA, Brodmann area.

Figure 2

ROC curve analysis of the mean ReHo values for altered brain regions. Notes: The areas under the ROC curve were (A) LPreCG/PosCG (0.873) (P<0.001; 95%CI: 0.739–0.971); RPreCG/PosCG (0.875) (P<0.001; 95%CI: 0.763–0.987); LMFG (0.878) (P<0.001; 95%CI: 0.761–0.994), (EPs < HCs). (B) LSFG (0.860) (P<0.001; 95%CI: 0.747–0.973) and RIPL (0.873) (P<0.001; 95%CI: 0.759–0.986); LPrecu (0.832) (P<0.001; 95%CI: 0.710–0.955) (EPs > HCs). Abbreviations: AUC, area under the curve; ROC, receiver operating characteristic; ReHo, regional homogeneity; CI, confidence interval; EP, eye pain; HCs, healthy controls; PreCG/PosCG, precentral/postcentral gyrus; MFG, middle frontal gyrus; SFG, superior frontal gyrus; IPL, inferior parietal lobule; Precu, precuneus; L, left; R, right.