Frequency-dependent Alterations In The Amplitude Of Low-frequency Fluctuations In Patients With Acute Pericoronitis:a Resting-state FMRI Study

Objective:To apply the amplitude of low-frequency fluctuations(ALFF)method in restingstate functional magnetic resonance imaging to investigate the characteristics of altered brain spontaneous activity in patients with acute pericoronitis in different frequency bands(the typical band,slow-4 band and slow-5 band),and to improve the understanding of the central pathophysiological mechanisms in patients with AP and the effects of acute odontogenic pain on the central nervous system.Methods:Thirty-four right-handedness patients with acute pericoronitis were included in this study as the experimental group(AP group),while 31 volunteers matched for age,gender,education and right-handedness were recruited as the healthy control group(HC group).Resting-state functional MRI scans were performed on subjects in both groups,and the DPABI software package was applied to preprocess the data and extract the ALFF values in different frequency bands.Subsequently,a two-sample ttest was used to compare the differences in ALFF values between the two groups of subjects in different frequency bands(the typical band,slow-4 band and slow-5 band)and to analyze the correlation between ALFF values in the differential brain regions and clinical parameters.Results:(1)In the typical band,the AP group showed higher ALFF values in the left insula,left superior occipital gyrus,left inferior parietal lobule,left posterior cerebellar lobule and right postcentral gyrus compared with the HC group.(2)In the slow-4 band,compared with the HC group,the AP group showed higher ALFF values in the left superior occipital gyrus,right superior occipital gyrus and right middle occipital gyrus,while the ALFF values of the right cingulate gyrus and right superior temporal gyrus were decreased.(3)In the slow-5 band,the AP group showed higher ALFF values in the left insula and left superior occipital gyrus compared with the HC group.(4)In the typical band,the ALFF values of the left insula,left inferior parietal lobule and right postcentral gyrus in the AP group were negatively correlated with visual analogue scale(VAS).In the slow-4 band,the ALFF values of the right middle occipital gyrus were positively correlated with VAS in the AP group.In the slow-5band,the ALFF values of the left insula were negatively correlated with VAS in the AP group.Conclusions:(1)Based on the ALFF method,this study showed that AP patients have functional abnormalities in several brain regions at resting state,mainly involving different dimensions such as pain-related areas,default network and visual cortex,suggesting that AP patients may have central functional disturbances and reorganization.(2)In the frequency-dependent study,there were differences in abnormally active brain regions in AP patients in different frequency bands,which may reflect that different frequency bands have different sensitivities to abnormal cortical neuronal activity in AP patients,suggesting a frequency-dependent spontaneous brain activity in AP patients and providing new insights to explore the neurophysiological mechanisms of AP.