To Study The Plasticity Of Trigeminal Nerve In Patients With Primary Trigeminal Neuralgia By Diffusion Tensor Imaging

Objective: To determine the performance and differences of MRI diffusion tensor imaging(DTI)in trigeminal nerve of healthy people,trigeminal neuralgia(TN)with vascular compression and trigeminal neuralgia after microvascular decompression(MVD).To analyze the correlation between neurovascular morphological changes of TN and DTI manifestations,to determine the identification effect of DTI on TN and to screen the biological markers with postoperative effects.Objects and methods: From April in 2014 to September in 2017 a total of 92 patients with primary TN confirmed by surgery in our hospital including 12 patients after MVD and 45 healthy volunteers were enrolled in the study.All patients with TN met the diagnostic criteria for primary TN in the third edition of the IHS international classification of headache disorders(ICHD-3).All subjects were underwent conventional sequences and DTI sequences using the German Siemens Verio 3.0T superconducting magnetic resonance instrument.According to the degree of neurovascular compression,the all patients with TN were divided into three groups: group 1,the vessel “touches” the nerve without any visible displacement or atrophy of the nerve(n=33);in group 2,that the vessel causes displacement of the nerve without atrophy(n=25);in group 3,the nerve caused nerve displacement and atrophy of the nerve(n=34).CSA,MD,FA,AD and RD values of bilateral trigeminal nerve were measured.Normality test were performed on all data,line parameter test for data conforming to normal distribution and non-parameter test for data not conforming to normal distribution.Paired t-test was used to compare the differences of the parameters of the bilateral trigeminal nerve between healthy people and patients with TN.Oneway analysis of variance(ANOVA)and least significant difference(LSD)was used to compare the differences of bilateral trigeminal nerve between TN patients and healthy volunteers,as well as the differences of each parameter of the affected side trigeminal nerve between each group of TN patients.Paired t-test was used to compare the differences between various parameters of the affected side trigeminal nerve in the same patient before and after MVD.Pearson correlation coefficients analysis was used to study the correlation between FA value,MD value,AD value,RD value,CSA and visual analogue scale(VAS)of the patients with TN.Receiver operating characteristic curve(ROC)was used to analyze the identification degree of each parameter of DTI,including FA value,MD value,AD value,RD value and CSA,so as to determine the optimal threshold.T test,ANOVA and correlation test were considered statistically significant with p<0.05.Results :(1)There were no significant differences in CSA,FA,MD,RD and AD values between bilateral trigeminal nerve in group 0(P>0.05);(2)There were significant differences in the values of CSA,FA,MD,RD and AD of trigeminal nerve between the affected and contralateral sides of the patients with TN(P<0.05).There were also significant differences in the values of CSA,FA,MD,RD and AD of trigeminal nerve between the affected and contralateral sides in the 1,2 and 3 groups of the patients with TN(P<0.05);(3)There was no statistically significant difference in CSA,FA value,MD value,RD value and AD value between bilateral trigeminal nerve of healthy people and contralateral sides of the patients with TN(P>0.05).However,there were significant differences in CSA,FA,MD,RD and AD between bilateral trigeminal nerve of healthy people and affected sides of TN patients(P<0.05);(4)The CSA and FA values of the affected side of the patients with TN in the 1 and 2 groups were greater than 3 groups,the difference was statistically significant(P<0.05).The MD value of the affected side of the patients with TN in the 1 group was less than 3 groups,the difference was statistically significant(P< 0.05);the RD values of the affected side of the patients with TN in 1,2 group were less than 3 groups,the difference was statistically significant(P<0.05);there were not significant differences in the affected side of the patients with TN among the AD values of the trigeminal nerve in 1,2,3 group,the CSA,FA values,MD value,RD value of the trigeminal nerve in 1,2 group and the MD value in 2,3 groups(P>0.05);(5)The CSA,MD value,AD value and RD value of the affected side in the same patient with TN were decreased in different degrees after microvascular decompression(MVD)compared with that before operation,and the differences were significant(P<0.05).FA value increased significantly after surgery compared with that before and there was a significant difference(P<0.05).After MVD,the differences of the FA,MD and RD values between the operative side and the contralateral side were significantly reduced,with no statistical significance(P>0.05).The CSA and AD value of the affected side were lower than that of the contralateral side,and the difference were statistically significant(P<0.05);(6)VAS of TN patients had no significant correlation with the MD value,AD value,RD value,FA value and CSA of the affected side of the trigeminal nerve(R values were 0.190,0.191,0.173,-0.0.092,-0.196,respectively,P>0.05);(7)The FA value,MD value,AD value,RD value and CSA of trigeminal nerve all have a high degree of identification of TN.FA value was the most reliable for the identification of TN,with an AUC of 0.960,a sensitivity of 89.13% and a specificity of 100%,and the value showed significant differences(P<0.0001).The CSA,MD,AD and RD values were also statistically significant(P<0.0001)(AUC were 0.840,0.814,0.626,and 0.890,respectively.The sensitivity and specificity were 57.61%,100%,55.43%,95.56%,48.91%,75.56%,67.93%,and 97.78%,respectively).Conclusion: DTI is a safe and non-invasive MRI examination method,which can reflect the changes of trigeminal nerve microstructure.Healthy people and patients with TN trigeminal DTI performance difference to be markedly,Nerve blood vessels in the form of different can also make regular changes in the trigeminal DTI,DTI multiparameter imaging of TN has a high degree of recognition,and can provide reliable effect evaluation for patients with TN MVD surgery of biological indicators.