Multimodal MRI-Based Study On Patients With Postherpetic Neuralgia

Objective: The present study was to investigate the effect of postherpetic neuralgia(PHN)on the cerebral function and anatomy in patients using magnetic resonance imaging,and to compare the discrepency before and after treatment,thereby probing the pathogenetic and developing mechanism and providing reference data for estimating therapeutic efficacy.Methods:1.Data acquisition: Fuctional and structural images were acquired from 17 left-sided PHN patients and 17 age-,sex-matched healthy volunteers using resting-state functional magnetic resonance imaging(rsfMRI),voxel-based morphometry(VBM),diffusion kurtosis imaging(DKI).2.To analyze the functional and anatomical alterations in the brain of PHN patients: the regional homogeneity(ReHo)and fraction amplitude of low frequency fluctuation(fALFF)were compared between two group to evaluate the differences of functional activity.The discrepancies in volume and density of gray matter between two groups were analyzed and compared applying VBM-DARTEL.The DKI parameters including axial,radial,mean parameters and fractional anisotropy(FA)were compared to explore the microstructural lesions in the brain of PHN patients.Correlation analysis was performed between the corresponding parameters in the regions where notable differences between two groups existed and clinical materials.3.To estimate the effect of comprehensive therapy on the functional and structural abnormality in the brain of PHN patients: 8 cases of above-mentioned patients accepted MRI scanning with identical sequences again 6 months after comprehensive treatments including medications,physical and neurolytic therapy.The acquired data were used for paired t test to observe the alterations before and after treatment.Reults: 1.As compared to healthy volunteers,ReHo values increased in the bilateral thalamus,left middle frontal gyrus,etc.and decreased primarily in the bilateral middle temporal gyrus in the left cerebellar posterior lobe of PHN patients.fALFF values increased in the bilateral putamen and right cerebellar anterior lobe,and decreasd in the frontal lobe such as bilateral middle frontal gyrus etc.(P<0.05,corrected by AlphaSim).ReHo value in the left thalamus was positively correlated with VAS score(r=0.60,P=0.011),ReHo value in the left middle temporal gyrus was negatively correlated with VAS score(r=-0.78,P<0.001).The gray matter volume of PHN patients decreased remarkably in the bilateral postcentral gyrus,right parahippocampal gyrus,left cerebellar anterior lobe,etc..The gray matter density reduced in the bilateral caudate,cingulate gyrus etc.(P<0.001,cluster size>50).DKI analysis indicated that the axia diffusivity(AD),radial diffusivity(RD)and mean diffusivity(MD)of PHN patients elevated in the bilateral frontal gyrus,insula,putamen,etc.;the axia kurtosis(AK),radial kurtosis(RK)and mean kurtosis(MK),as well as FA value decreased in bilateral thalamus,insula,frontal gyrus,middle temporal gyrus etc.(P<0.05,corrected by AlphaSim).2.In PHN patients,fALFF and ReHo values in the frontal lobe,cuneus,middle temporal gyrus,left cerebullum,etc.,coupled with gray matter volume in the cerebullum and FA,AK,AD and MD in the temporal lobe altered to different extent after comprehensive treatment.Conclusion: 1.Functional and anatomical changes are detected in the brain regions related to pain perception and integration in PHN patients,which may play an important role in the pathogenetic and developing process of PHN.2.Comprehension treatment can partly alter the cerebral functional and structural abnormality of PHN patients.Investigation to the level of alteration using MRI may provide reference for evaluation of therapeutic efficiency.