Pathogenesis Of Cranial Nerve Hyperactive Dysfunction Disease And Effectiveness Of Microvascular Decompression

OBJECTIVESTo identify the abnormalities in spontaneous brain activity among patients with primary trigeminal neuralgia(TN)or hemifacial spasm(HFS)and evaluate the long-term efficacy and safety of microvascular decompression(MVD)for treating TN or HFS and investigate the value of lateral spread response(LSR)and brainstem auditory evoked potential during MVD for HFS.METHODS38 patients with primary HFS,11 patients with primary TN and 34 healthy control(HC)subjects were recruited and underwent resting-state blood oxygen level dependence functional magnetic resonance imaging(BOLD-fMRI)scanning.All acquired MRI data were analyzed using the regional homogeneity(ReHo)method to determine the changes of brain activity in cerebral cortex and subcortical gray matter nuclei.A total of 425patients with primary TN,39 patients with TN secondary to intracranial tumor and 1574cases with primary HFS who underwent surgery for facial pain and ticin last two decades at the Ruijin Hospital,School of Medicine,Shanghai JiaoTong University(Shanghai,China)were analyzed,Kaplan-Meier survival curves was generated,Univariate analysis and Cox proportional-hazards regression were performed to identify factors associated with the maintenance of long-term facial pain or tic relief.Additionally,120 patients and146 patents with HFS were treated by MVD with or without intraoperative electrophysiological monitoring,the success rate and complications were statistically compared.RESULTS(1)Compared with HC volunteers,patients with primary TN had significantly increased ReHo values in premotor area(M1),primary and secondary somatosensory cotex(S1,S2),prefrontal cortex,insula,thalamus,hippocampus and brain stem,the largest difference in excitable voxel was exhibited in M1 with 1566mm~3,the most increased ReHo value was founded in brainstem(t=4.45);decreased ReHo values were disclosed in supplementary motor area,cingulate cortex(CC)and periaqueductal gray matter(PAG),the largest difference in depressed voxel was showed in CC with 1134mm~3,the most decreased ReHo value was founded in PAG(t=-3.25)(P<0.01,AlphaSim corrected)?HFS patients had significantly increased ReHo values in pons,posterior lobe of cerebellum and M1,the largest difference in excitable voxel was exhibited in M1 with1458mm~3,the most increased ReHo value was founded in pons(t=3.83);decreased ReHo values were disclosed in supplementary motor area,superior temporal gyrus,precuneus,middle frontal gyrus and CC,the largest difference in depressed voxel and ReHo value was showed in CC(V=945mm~3,t=-3.69,P<0.01,AlphaSim corrected).(2)The rate of primaryTN cases response to MVD was 89.3%at 1 year,75.6%at 5 years,and 71.2%at 8 years.Typical clinical presentation,arterial vessel compression,and age?60 years at the time of surgery were independent predictors of an excellent outcome.Microsurgery was effective in 89.17%of cases with tumor-related TN 6 years postoperatively.Prognostic analysis suggested that total tumor removal were positively correlated with excellent long-term outcomes for tumor-related TN(P=0.032).Kaplan-Meier curve of HFS patients after MVD showed tic was relieved in 93.7%at 1year,90.13%at 5 years,and estimated to 89.3%at 8 years,and the delayed cure rate was observed in 19.6%of cases.Clear-cut neurovascular compression was significantly correlated with excellent operative results.(3)The cured rate of 120 patients with intraoperative LSR and BAEP monitoring showed no significant difference with the results of 146 cases withoutelectrophysiological monitoring neither 1week nor 12 months after MVD.However,lower incidence of hearing dysfunction was found in monitoring group(P=0.04).CONCLUSIONS(1)Our data demonstrate hyperexcitability of trigeminal nociceptive system and dysfunction of diffuse noxiouspain inhibitory control.These changes might improve individual susceptibility to peripheral trigeminal nerve stimulation and lead to the onset of facial pain.(2)HFS patients have significant abnormalities in spontaneous brain activity involving facial motion control system,and the disturbance of original balance between facial motionactivation and inhibitory may provide newly insights into the pathophysiology underlying HFS.(3)Microsurgery is an effective and safe treatment modality for HFS,primary and tumor-related TN patients,especially in those with typical clinical presentation and clear-cut neurovascular or neuro-tumor contact.(4)LSR and BAEP electrophysiological monitoring during MVD for HFS treatment have limited assistance on improvement of surgical efficiency,but it may reduce the incidence of hearing dysfuntion related to operation.