Altered intrinsic brain activities in patients with acute eye pain using amplitude of low-frequency fluctuation: a resting-state fMRI study

Abstract

Objective: Many previous studies have reported that pain symptoms can lead to significant brain function and anatomical changes, whereas the intrinsic brain activity changes in acute eye pain (EP) patients remain unknown. Using the amplitude of low-frequency fluctuation (ALFF) method, this study aimed to evaluate the spontaneous brain activity alterations and their relationships with clinical features in acute EP patients.

Participants and methods: A total of 20 patients with EP (15 males and 5 females) and 20 healthy controls (HCs; 15 males and 5 females) closely matched in age, sex, and education underwent resting-state functional magnetic resonance imaging scans. The ALFF method was applied to assess spontaneous brain activity changes. The ALFF values of the EP patients were distinguished from those of the HCs using a receiver operating characteristic curve. Pearson's correlation analysis was used to investigate the relationships between the mean ALFF signal values from many brain regions and the clinical features in EP patients.

Results: Compared with the HCs, acute EP patients had significantly lower ALFF in the left and right precentral/postcentral gyrus and left precuneus. In contrast, acute EP patients showed higher ALFF values in the right and left parahippocampal gyri and left caudate. However, no relationship was observed between the mean ALFF signal values from the different areas and clinical manifestations in the acute EP patients.

Conclusion: We demonstrated that acute EP patients showed abnormal intrinsic brain activities in the precentral/postcentral gyrus and limbic system, which might provide useful information for explaining neural mechanisms in EP patients.

Keywords: ALFF; blood oxygenation level dependent; eye pain; functional magnetic resonance imaging; resting state.

Figure 1

Spontaneous brain activity in the EPs versus HCs. Notes: (A and B) Significant activity differences were observed in the LPreCG/PosCG, RPreCG/PosCG, LPrecu, RParaHG, LParaHG, and left caudate. The red or yellow denotes higher ALFF values, and the blue areas indicate lower ALFF values, respectively (p<0.01 for multiple comparisons using Gaussian-random field theory, z>2.3, p<0.01, cluster >40 voxels, FDR corrected). (C) The mean values of altered ALFF values between the EPs and HC groups. Abbreviations: ALFF, amplitude of low-frequency fluctuation; EP, eye pain; FDR, false discovery rate; HC, healthy control; LParaHG, left parahippocampal gyrus; LPreCG/PosCG, left precentral/postcentral gyrus; LPrecu, left precuneus; RParaHG, right parahippocampal gyrus; RPreCG/PosCG, right precentral/postcentral gyrus.

Figure 2

ROC curve analysis of the mean ALFF values for altered brain regions. Notes: (A) The areas under the ROC curve were 0.827 (p<0.001; 95% CI: 0.696–0.959) for LPreCG/PosCG; RPreCG/PosCG (0.873) (p<0.001; 95% CI: 0.766–0.979); LPrecu (0.847) (p<0.001; 95% CI: 0.725–0.970), (EPs < HCs). (B) RParaHG (0.905) (p<0.001; 95% CI: 0.815–0.995) and LParaHG (0.910) (p<0.001; 95% CI: 0.820–1.000); left caudate (0.947) (p<0.001; 95% CI: 0.884–1.000) (EPs > HCs). Abbreviations: ALFF, amplitude of low-frequency fluctuation; CI, confidence interval; EP, eye pain; HC, healthy control; LParaHG, left parahippocampal gyrus; LPreCG/PosCG, left precentral/postcentral gyrus; LPrecu, left precuneus; RParaHG, right parahippocampal gyrus; RPreCG/PosCG, right precentral/postcentral gyrus; ROC, receiver operating characteristic.