| Objectives:Primary trigeminal neuralgia(PTN)is a clinically common chronic neuropathic pain disorder.Accumulating evidence suggests that chronic pain causes central nervous system abnormalities and that pain-related central regulatory regions may play an important role in the pathogenesis of PTN.This study aimed to combine three-dimensional pseudo-continuous arterial spin labeling imaging(3D pCASL)for cerebral blood flow(CBF)and resting-state blood oxygen level-dependent functional magnetic resonance imaging(BOLD-fMRI)for regional homogeneity(ReHo)and functional connectivity strength(FCS)analysis to investigate whether patients with PTN have altered cerebral perfusion patterns and whole-brain or local neuronal activity abnormalities,and the relationship between abnormal brain regions and clinical features.From the theory of neurovascular coupling,the correlation analysis of cross voxel CBF-ReHo and CBF-FCS and the ratio analysis of ReHo/CBF and FCS/CBF were used to further explore the alteration of neurovascular coupling and its clinical significance in patients with PTN,respectively.Materials and Methods:Twenty-eight PTN patients and 30 sex-and age-matched healthy subjects were included in this study.The Philips 3.0T magnetic resonance scanner was used to acquire data from the study subjects,and the main sequences included 3D pCASL,resting-state BOLD-fMRI and 3D high-resolution structural images,and the Hamilton Anxiety Scale and 24-item Hamilton Depression Scale were used to assess the psycho-psychiatric status of all subjects,and the visual analog scale was applied to assess the pain intensity of PTN patients.Using the ReHo method to assess regional spontaneous neuronal activity,the FCS method to assess global spontaneous neuronal activity,and the 3D pCASL perfusion data for measuring regional CBF in the brain,calculating the across-voxel CBF-ReHo and CBF-FCS correlations to quantitatively evaluate the global neurovascular coupling,and computing the ReHo/CBF and FCS/CBF ratios of each voxel to quantify the regional neurovascular coupling.Analyzing the changes of regional and global spontaneous neuronal activity,regional CBF and neurovascular coupling in brain regions of PTN patients.Partial correlation analysis was performed to illustrate the relationships between abnormal brain regions and clinical characteristics.Results:Compared with healthy controls(HCs),PTN patients had increased CBF in the thalamus,left insula and bilateral middle frontal gyrus.Compared with HCs,PTN patients had increased FCS in the bilateral orbitofrontal cortex,decreased FCS in the left postcentral gyrus,and decreased ReHo in the bilateral postcentral gyrus and right middle occipital gyrus.Compared with HCs,the whole-brain CBF-ReHo coupling was significantly decreased in PTN patients,and PTN patients had altered ReHo/CBF and FCS/CBF ratios in several brain regions,including the middle temporal gyrus,middle occipital gyrus,cuneus,inferior parietal lobule,precentral gyrus,postcentral gyrus,and middle cingulate gyrus.In addition,the abnormal ReHo/CBF ratio of left cuneus in PTN patient was significantly negatively correlated with depression and anxiety scores,ReHo/CBF ratio of left precentral gyrus was significantly positively correlated with depression scores,and ReHo/CBF ratio of the right middle temporal gyrus was significantly positively correlated with pain intensity.Conclusions:PTN patients showed alterations in brain function,cerebral blood flow,and neurovascular coupling in several brain regions,and these alterations were mainly present in different brain regions involved in pain cognitive-emotional interaction,pain perception,and regulation.This suggests that combining the results of cerebral blood flow and function and their neurovascular coupling can help us further insight into the neuropathological mechanisms of PTN. |
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