A Multimodal Magnetic Resonance Study On The Mechanism Of Acupuncture Effect In Stroke Hemiplegia Based On The Motor Cortex Connectome

Objective:This study focused on the bilateral regulation and coordination of the brain,with bilateral motor cortex connection group as the main research site.The study based on structural magnetic resonance imaging technology(T1,DTI)and functional magnetic resonance imaging technology(blood oxygen level-dependent functional magnetic resonance imaging,BOLD-fMRI)and combined with clinical motor dysfunction(Fugl-Meyer Assessment,FMA).Multimodal analysis(VBM,FA and FC)was used to express the bilateral regulation problems after stroke injury and in the process of functional recovery from multiple perspectives and levels,as well as the brain functional response characteristics of bilateral motor cortex connection group when acupuncturing at true/sham Yanglingquan(GB34)acupoints.Methods:In this study,66 patients with unilateral motor pathway injury(left or right hemiplegia)within 2 months after stroke onset were included.The lesions were mainly located in basal ganglia and/or corona radiata of unilateral motor pathway.The simplified Fugl-Meyer scale(FMA)was used to evaluate the motor dysfunction of patients and the reseachers completed the collection of clinical background information.At the same time,66 age-and gender-matched healthy subjects were included.All subjects enrolled in this study would undergo one MRI scan,including resting-state fMRI scan,T1 scan,acupuncture-state scan and diffusion-tensor imaging(DTI)scan.The ratio of true acupoint stimulation to sham acupoint stimulation was 2:1 in the stroke hemiplegic patients group and healthy subjects group,respectively.Needle sensation scales were collected for all subjects after MRI scan.Voxel-based morphological analysis(VBM),fractional anisotropy(FA)and functional connectivity(FC)were used to describe the brain structure and function.Independent sample T-test was used to compare the differences between groups,while paired sample T-test was used to compare the differences within groups.Spearman test was used to verify the correlation between FMA,course of disease and needling sensation level and FC of cerebral motor cortex connection group.P<0.05 represents that the difference is statistically significant.Results:In the image preprocessing stage,the left and right images were flipped and averaged,that is,the affected side of all the following images was right side.1 Results of general data and clinical indicatorsThe age and gender data of the 4 groups were tested,and the P values within each group were>0.05.There was no statistical difference in the basic data of each group,which represented that they can be compared.There was no statistical difference in FMA between the 2 stroke groups(P=0.474>0.05).2 Results of MRI2.1 Voxel-based morphology(VBM)was used to analyze the difference of gray matter volume(GMV)between stroke hemiplegic patients and healthy subjectsThe structural MRI data of all stroke hemiplegic subjects and all healthy subjects were analyzed by VBM.The results showed that GMV in thalamus(R),caudate nucleus(R)and lateral ventricle(R)of stroke hemiplegic subjects were significantly lower than those of healthy subjects.2.2 TBSS was used to analyze the brain regions with significant differences in FA values between stroke hemiplegic subjects and healthy subjectsBased on TBSS,the FA values of all stroke hemiplegic subjects and healthy subjects were obtained by processing DTI data.The results showed that compared with healthy subjects,the FA values of stroke hemiplegic subjects were significantly lower in the following brain areas:Genu of corpus callosum(R),Body of corpus callosum(R),Corticospinal tract(R),Cerebral peduncle(R),Anterior limb of internal capsule(R),Posterior limb of internal capsule(R),Retrolenticular part of internal capsule(R),Anterior corona radiate(L),Anterior corona radiate(R),Superior corona radiate(L),Superior corona radiate(R),Posterior corona radiate(R),Posterior thalamic radiation(R),External capsule(R),Superior longitudinal fasciculus(R),Superior fronto-occipital fasciculus(R),and Tapetum(R).(P<0.001).2.3 Effect of acupuncture at true/sham Yanglingquan(GB34)acupoint on FC values of bilateral motor cortex connection group in different test groupsThe results showed that after stroke,in the resting-state,compared with healthy people,the related brain areas of FC values decreased in bilateral motor cortex connection group included:M1(left,L)-M1(right,R),M1(L)-PMC(R),M1(R)-SMA(L),M1(R)-SMA(R),M1(R)-PMC(R).The FC values between M1-SMA and Ml-PMC on the right side of the subjects increased when acupuncture at true Yanglingquan(GB34)acupoint of healthy people;The FC values between M1(R)-M1(L),SMA(R)-M1(L),SMA(L)-M1(R),SMA(R)-M1(R),SMA(R)-M1(R)and SMA(L)-PMC(R)increased when acupuncture at true Yanglingquan(GB34)acupoint of apoplectic hemiplegic patients;The FC values of Ml-SMA and Ml-PMC on the right side of stroke hemiplegic patients were lower than those of healthy subjects when acupuncture at true Yanglingquan(GB34)acupoint of healthy subjects and stroke hemiplegic patients.However the P value was equal to 0.05,which meant the difference between groups was not significant.The FC values of M1-PMC on the right side of the healthy subjects increased when acupuncture at sham Yanglingquan(GB34)acupoint;The FC values between the Ml-SMA and the SMA-PMC on the right side increased when acupuncture at sham Yanglingquan(GB34)acupoint of apoplectic hemiplegia patients;The FC values of right M1-SMA and right SMA-PMC of stroke hemiplegic patients were lower than those of healthy subjects when acupuncture at sham Yanglingquan(GB34)acupoint in healthy subjects and stroke hemiplegic patients.The results showed that FC values between Ml of bilateral hemispheres of healthy subjects were higher when acupuncture at true Yanglingquan(GB34)acupoint than when acupuncture at sham Yanglingquan acupoint;The FC values of M1,SMA in bilateral hemispheres and SMA-PMC on left side of patients were higher when stimulating the true Yanglingquan(GB34)acupoint compared to when stimulating the sham Yanglingquan(GB34)acupoint.3 Correlation analysis between clinical indicators and FC values of motor cortex connection groupResting-state FC values of bilateral M1 were significantly positively correlated with FMA values in stroke hemiplegia patients;Resting-state FC values of ipsilateral M1-SMA were significantly positively correlated with the course of stroke;There was no statistical significance in the correlation analysis between the needle sensation grade and the FC values of the motor cortex connection group.Conclusion:After stroke,gray matter volume atrophy mainly occurrs in the lesion side;after unilateral motor pathway stroke,the structure of the brain changes bilaterally,that is,the damage appears in the affected side and at the same time,it will also appear in the corresponding areas of the uninjured contralateral brain.The potential mechanism of structural damage in the contralateral brain region after stroke may be the damage of unaffected corpus callosum fibers;in addition to the motor-related white matter fiber structural damage,the non-motor-related white matter fiber will also be affected in the affected side.After unilateral motor pathway damage,the functional connectivity of the motor cortex connection group appears bilateral changes.The impairment of unilateral motor pathway can result in the decrease of functional connectivity in the motor cortex connection group of the affected side,and at the same time,the decrease of functional connectivity between the affected side and the unaffected side,especially the decrease of functional connectivity between the M1 area of the affected side and other brain areas.The promotion of acupuncture on the rehabilitation of hemiplegia after stroke is realized through the bilateral and holistic regulation of the motor cortex connection group;acupuncturing at Yanglingquan(GB34)can promote the functional connectivity of related sites in bilateral motor cortex connection group within the affected hemisphere and between the two hemispheres;acupuncturing at acupoints can activate the functional connectivity of brain regions which are inhibited by stroke,making the damaged FC closer to the state of healthy people;there is a significant difference between stimulating acupoints and non-acupoints in the response of the brain central neuron in the motion-related brain regions;when true Yanglingquan(GB34)acupoint is stimulated,it will promote bilateral remodeling and functional recovery of cerebral motor cortex connection group in stroke hemiplegic patients.