Characteristics And Application Of Vestibular Evoked Myogenic Potentials In Vestibular Paroxysmia

Background and ObjectiveVestibular paroxymia(VP)is a peripheral vestibular disease characterized by vertigo.The incidence is 3.9% of out-patients with vertigo.There was no gender difference in the prevalence,and it was more common in the young and 40 to 70 years of age.Recurrent episodes of transient vertigo is the main clinical manifestation,which may be accompanied by tinnitus,hypersensitivity,hearing loss,gait and posture instability,balance disorders,and often accompanied by nausea,vomiting and other autonomic nervous dysfunction symptoms.Certain specific movements such as posture or head position changes,deep breathing can be induced,riding and using elevators,mental stress and so on may promote the onset of VP.The pathogenesis of VP is still controversial,and the more recognized mechanism is demyelination of nerve fibers after compression of vestibulocochlear nerve.And the vestibular nerve is divided into the superior vestibular nerve and the inferior vestibular nerve.The clinical manifestations were related to the compression site and the involved nerve.Repeated vertigo attacks bring a lot of pain to the patients,even affect the normal work,study and life,and make a great impact on the individual,family and even the society.Because the clinical symptoms of VP are atypical,the pattern of onset is similar to that of benign paroxysmal positional vertigo,and the patients with hearing loss or tinnitus are similar to Meniere's disease and sudden deafness.The misdiagnosis rate of the disease is high due to the inaccuracy of the patient's medical history and the lack of specific auxiliary examination.However,with the continuous improvement of magnetic resonance imaging technology and the rapid development of neurophysiological examination technology,the disease has received more and more attention from the medical community and reports are increasing.For example,MRI shows that the vestibulocochlear nerve and blood vessels are oppressing each other.The I-III peak interval of the brainstem auditory evoked potential is prolonged and vestibular evoked myogenic potentials abnormalities.VEMPs is an electrophysiological indicator that reflect the function of the vestibular and brainstem.It is the electromyographic response recorded by the skeletal muscle on the surface of the nervous body through electrodes under the stimulation of intense sound and other stimuli in peripheral otoliths.It mainly includes ocular vestibular evoked potential and cervical vestibular evoked potential.oVEMP reflects the superior vestibular nerve function and cVEMP reflects the subvestibular nerve function.In recent years,with the development of VEMPs research,it has been widely used in the diagnosis of peripheral vertigo diseases such as Meniere's disease,vestibular neuritis,benign paroxysmal positional vertigo and so on.It has been reported that VEMPs appears abnormal in different degrees in VP patients,and it has certain value in diagnosis.It has also been reported that VEMPs is neither sensitive nor specific to VP.At present,there is no definite study on whether there are some characteristics in VEMPs of VP,and there are no reports on the specificity of oVEMP and cVEMP in VP.Therefore,in this study,20 patients with VP with neurovascular cross compression(NVCC)on MRI and 20 healthy controls were examined with the neuroelectrophysiological examination of VEMPs.The extraction rate and parameters of oVEMP and cVEMP in patients with VP were analyzed,and the value of VEMPs in the pathogenesis,precise localization,evaluation of curative effect and prognosis and differential diagnosis of VP were discussed.Materials and Methods20 VP patients with NVCC on MRI in the Department of Neurology,second affiliated Hospital of Zhengzhou University,were collected as observation group from December 2016 to March 2018.In the same period,20 healthy persons without NVCC in MRI were used as control group(all patients were examined with field strength and the same sequence of cranial MRI).All participants were enrolled in the same stimulation mode for VEMPs.The NVCC side of VP,the non-NVCC side of VP,the Extraction rate of oVEMP and cVEMP in control group and various parameters(including P1 latency,N1 latency,the amplitudes of P1-N1)were compared between groups and within groups.The effects of VP on the extraction rate,latency and amplitude of VEMPs and the compression site of VP were analyzed.Results(1)In VP group,22 ears(55%)were induced by oVEMP,16 ears(84.21%)were induced by non-NVCC side(28.57%),6 ears(28.57%)of NVCC,the difference was statistically significant(P<0.05),and 35 ears(87.50%)in control group;In VP group,26 ears(65%)were induced by cVEMP,17 ears(89.47%)were induced by non-NVCC side,which was significantly higher than 9 ears(42.86%)by NVCC side(P<0.05),and 35 ears(87.50%)by control group.There were significant differences in the extraction rates of oVEMP?cVEMP between the NVCC side of VP group and the control group(P<0.05).There was no significant difference between the non-NVCC side of VP group and the control group(P>0.05).(2)In group VP,there was no significant difference in the extraction rate between cVEMP and oVEMP(2=0.83,P>0.05).(3)In VP group,the latency of NVCC side was prolonged and the amplitude was decreased,VEMPs parameters were significant differences between NVCC side and non-NVCC side(P<0.05).There were significant differences between NVCC side of VP group and control group(P<0.05).There was no significant difference between non-NVCC side of VP group and control group(P>0.05).Conclusions(1)Extraction rate of VEMPs on the NVCC side of VP patients were decreased,latency prolonged,amplitude decreased,NVCC is one of the pathogenesis of VP,VEMPs can help to distinguish the lesion side.(2)In the patients with VP,the superior and subvestibular nerve conduction pathwaies were abnormal on the side of NVCC.