The lesion site of vestibular dysfunction in Ramsay Hunt syndrome: a study by click and galvanic VEMP

Ramsay Hunt syndrome (RHS) is characterized by vestibulocochlear dysfunction in addition to facial paralysis and auricular vesicles. The present study investigated the lesion site of vestibular dysfunction in a group of 10 RHS patients. Caloric testing, vestibular evoked myogenic potentials by click sound (cVEMP) and by galvanic stimulation (gVEMP) were used to assess the function of the lateral semicircular canal, saccule, and their afferents. The results of caloric testing (all 10 cases showed canal paresis) mean the existence of lesion sites in lateral semicircular canal and/or superior vestibular nerve (SVN). Abnormal cVEMPs in 7 patients mean the existence of lesions in saccule and/or inferior vestibular nerve (IVN). Four of the 6 patients with absent cVEMP also underwent gVEMP. The results of gVEMP (2 absent and 2 normal) mean that the former 2 have lesions of the vestibular nerve, and the latter 2 have only saccular lesions concerning the pathway of VEMPs. Thus, our study suggested that lesion sites of vestibular symptoms in RHS could be in the vestibular nerve and/or labyrinth, and in SVN and/or IVN. In other words, in the light of vestibular symptoms, there is the diversity of lesion sites.     

听神经病伴发前庭下神经损害

OBJECTIVE: To investigate if auditory neuropathy have inferior vestibular nerve (IVN) lesion and to explore the relation between AN and the IVN lesion by vestibular evoked myogenic potentials (VEMPs). METHODS: VEMPs were observed in 13 patients with auditory neuropathy. And the relation among the duration, hearing threshold of lower frequency and speech discrimination score with VEMPs were observed. RESULTS: Fifty-four percent patients in auditory neuropathy had abnormal VEMPs. They took the form of lower amplitude and no response. The statistical analysis showed that the abnormality of VEMPs had no correlation with lower frequency hearing loss, the duration and speech discrimination score. CONCLUSIONS: The IVN dysfunction may coexist with auditory neuropathy, having lesion in the IVN. However, there was no significant relation between the severity of AN and VEMPs, which meant that AN and inferior vestibular neuropathy had their independence to some extent.     

前庭诱发肌源性电位的正常人群观察

目的:观察我国正常青年人群中前庭诱发肌源性电位(VEMP)出现的阳性率及各项参数指标。方法:选取52例(男31例,女21例)21~22岁正常健康人群,以短声为刺激声,单耳给声,同侧胸锁乳突肌(SCM)记录。结果:47例2耳均可引出VEMP,5例2耳均不能引出。总104耳中,94耳阳性,10耳阴性,阳性率90%。统计阳性耳各参数:p1潜伏期(15.97±3.22)ms、n2潜伏期(24.41±2.46)ms、p1n2间期(8.41±2.06)ms,幅值(33.27±14.37)μV,阈值(93.67±5.20)dB nHL。统计47例正常人同一个体耳内差异的各参数为p1潜伏期(0.97±1.31)ms,n2潜伏期(1.23±1.30)ms,p1n2间期(0.95±1.21)ms,幅值(10.04±11.88)μV,阈值(2.29±2.56)dB nHL。男女各参数比较差异无统计学意义。结论:绝大部分正常人可引出VEMP。VEMP的引出体现该侧耳球囊→前庭下神经→脑干前庭神经核→前庭脊髓通路→颈肌运动神经元这条反射途径的完整性。VEMP可能成为一种检测前庭终器及其传导通路完整性的方法。     

听神经病伴发前庭下神经损害

目的 通过检测13例听神经病患者的前庭诱发的肌源性电位(vestibular evokedmyogenic potentials,VEMPs),了解听神经病患者是否同时伴发前庭下神经损害,探讨前庭下神经损害与听神经病的关系。方法 记录13例听神经病患者VEMPs,观察VEMPs表现形式;分析病程、低频听阈及言语识别率与VEMPs的关系。结果 13例听神经病患者中有7例存在VEMPs异常,占54％。异常的表现形式为VEMPs低振幅和VEMPs不能引出。正常VEMPs与异常VEMPs在低频听力损失、病程和言语识别率3个方面差异无显著性(P>0.05)。结论 部分听神经病患者伴发前庭下神经功能异常,说明两者病变可以同时并存;听神经病患者的病变程度方面与VEMPs无明显直接相关性,说明听神经病与前庭下神经损害两者之间又具有相对独立性。     

Laterality of vestibular evoked myogenic potentials

To clarify the laterality of acoustically evoked vestibulocollic reflexes with a short latency (vestibular evoked myogenic potentials, VEMPs). responses on the bilateral sternocleidomastoid muscles (SCMs) to unilateral acoustic stimulation were studied. Twenty-one healthy volunteers were enrolled. Surface electrodes were placed on the upper half of each SCM (active) and on the lateral end of the upper sternum (reference). Clicks and 500-Hz tone-bursts (95dB nHL) were used. All subjects showed positive-negative biphasic responses on the ipsilateral SCM by clicks and tone-bursts. Click-stimulation of 41 of the 42 ears did not evoke any response on the contralateral SCM. However, in one ear, positive-negative biphasic responses were evoked on the contralateral SCM. Recordings on the contralateral SCM by tone-bursts showed no response in 32 ears, small positive-negative biphasic responses in four ears, and small negative-positive biphasic responses in six ears. These findings show that VEMPs are ipsilateral-dominant, basically consistent with the hypothesis that they are of saccular origin.     

Laterality of vestibular evoked myogenic potentials

To clarify the laterality of acoustically evoked vestibulocollic reflexes with a short latency (vestibular evoked myogenic potentials, VEMPs), responses on the bilateral sternocleidomastoid muscles (SCMs) to unilateral acoustic stimulation were studied. Twenty-one healthy volunteers were enrolled. Surface electrodes were placed on the upper half of each SCM (active) and on the lateral end of the upper sternum (reference). Clicks and 500-Hz tone-bursts (95 dB nHL) were used. All subjects showed positive-negative biphasic responses on the ipsilateral SCM by clicks and tone-bursts. Click-stimulation of 41 of the 42 ears did not evoke any response on the contralateral SCM. However, in one ear, positive-negative biphasic responses were evoked on the contralateral SCM. Recordings on the contralateral SCM by tonebursts showed no response in 32 ears, small positive-nega-tive biphasic responses in four ears, and small negative-positive biphasic responses in six ears. These findings show that VEMPs are ipsilateral-dominant, basically consistent with the hypothesis that they are of saccular origin.     

Saccular Pathology Is Most Commonly Found in Patients With General Vestibular Disorders

ObjectivesThe first purpose of this study was to investigate the difference in the frequency of involvement of the superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) territories in general vestibular disorders, and to identify which IVN territory was more commonly involved in patients with IVN lesions. The second purpose was to investigate the correlation of the degree of each saccular and posterior semicircular canal (PSCC) dysfunction, as represented by the parameters of cervical vestibular evoked myogenic potential (cVEMP) and video head impulse test (vHIT), in patients with pathology of the IVN territory.MethodsIn total, 346 patients with dizziness who underwent the caloric test, cVEMP, and vHIT were enrolled. Canal weakness in the caloric test, interaural amplitude difference (IAD) of cVEMP, and vestibulo-ocular reflex gain of the vestibulo-ocular reflex gain of the posterior semicircular canal (p-VOR) in vHIT were analyzed.ResultsAmong the enrolled patients, 15.6% had total vestibular nerve dysfunction, 14.5% had solely SVN dysfunction, and 29.5% had solely IVN dysfunction. Isolated saccular pathology was most common in patients with IVN pathology, followed by those with total IVN dysfunction and PSCC dysfunction. IAD and p-VOR were statistically well correlated, and the correlation was strongest in patients with both pathologic IAD and pathologic p-VOR (n=23, r=0.944), followed by patients with normal IAD and pathologic p-VOR (n=27, r=0.762) and patients with pathologic IAD and normal p-VOR (n=106, r=0.339).ConclusionAbnormal results were more common in vestibular tests investigating the IVN than in vestibular tests investigating the SVN in patients with general vestibular disorders. Isolated saccular pathology was more frequent than PSCC or combined pathology in patients with IVN dysfunction. Patients with abnormal p-VOR in vHIT had a higher probability of having both saccular and PSCC pathologies than patients with an abnormal IAD. This study describes the characteristics of vestibular-system subregions and provides guidance for clinically interpreting the combination of cVEMP and vHIT results.     

A study on vestibular-evoked myogenic potentials via galvanic vestibular stimulation in normal people

Objectives

The aim of our study is to examine vestibular-evoked myogenic potentials (VEMPs) elicited by the galvanic vestibular stimulation in the sternocleidomastoid muscle (SCM) in healthy subjects for clinical applications of auditory neuropathy or vestibular neuropathy in the future.

The effects of click and tone-burst stimulus parameters on the vestibular evoked myogenic potential (VEMP)

Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.     

Sound-evoked myogenic potentials on the sternocleidomastoid muscle in monkeys

CONCLUSION: We recorded sound-evoked myogenic potentials of the sternocleidomastoid (SCM) muscle using awake monkeys. The characteristics of these potentials are similar to those of vestibular evoked myogenic potentials (VEMPs) in humans, suggesting that the sound-evoked myogenic potentials of the SCM muscle in monkeys may be utilized as an animal model of VEMPs. OBJECTIVE: The pathway of the VEMPs remains uncertain as no animal model has yet been used to record sound-evoked myogenic potentials in the SCM muscle. Therefore, the present study aimed to establish an animal model of VEMPs using macaque monkeys. MATERIALS AND METHODS: Four macaque monkeys were used. A pair of electrodes was attached on the SCM muscle ipsilateral side to the intense sound stimulation. RESULTS: The sound-evoked myogenic potentials of the SCM muscle exhibited a biphasic waveform. When a click at 125 dBSPL was applied, the peak latency of the first positive wave was 12.5 ms and was not delayed when the stimulating sound intensity was reduced. The thresholds of the myogenic potentials were 103 dBSPL, which were 43 dB higher than those of the auditory brainstem response (ABR). When a short tone burst was applied, the reactive optimal frequency of the myogenic potentials was relatively low (500-1000 Hz).     

An acoustically evoked short latency negative response in profound hearing loss infants

OBJECTIVE: A large negative deflection with a 3-4 ms latency within the auditory brainstem response has been reported in some profound hearing loss ears under intense stimuli in adult subjects. The wave has been termed the N3 potential or acoustically evoked short latency negative response and it is assumed to be a vestibular-evoked potential. The purpose of the current study was to investigate the relationship between the vestibular-evoked myogenic potentials and the acoustically evoked short latency negative response in infants with a functionless cochlea and normal or impaired semicircular canal. METHODS: Seventeen 3 months old infants with profound bilateral sensorineural hearing loss had acoustically evoked short latency negative responses and vestibular-evoked myogenic potentials recorded and caloric tests performed. RESULTS: No spontaneous symptoms of vestibular dysfunction were found in the examined infants. ASNR with medium latency 3.3 ms and threshold value 80-90 dB normal hearing level was elicited from 10 ears. VEMPs were present in 12 ears. ASNRs and VEMPs were absent in two ears with normal response to caloric stimulation. No response to caloric stimulation was elicited from other two ears with normal saccular function. For the ears with absence of ASNR, four had normal VEMP and the rest were considered to have saccular afunction. Significant correlation was found between the presence of ASNRs and VEMPs. CONCLUSION: Acoustically evoked short latency negative responses could be a valuable tool for assessing vestibular function in infants with profound sensorineural hearing loss.     

Influence of nerve of origin and tumor size of vestibular schwannoma on dynamic posturography findings

CONCLUSION: Condition 5-score (C5S) and vestibular ratio (VER) correlate, but condition-6-score (C6S) and mean overall balance score (MOBS) do not, with the size of an inferior vestibular nerve (IVN) vestibular schwannoma (VS). In IVN VS patients the visual system plays a major role in the maintenance of postural stability. OBJECTIVES: To test whether the size of a superior vestibular nerve (SVN) or IVN VS, as measured on MRI scans, correlates with computerized dynamic platform posturography (CDPP) findings and whether CDPP findings could preoperatively predict the nerve of origin of the VS. PATIENTS AND METHODS: This was a retrospective study. Seventy-five consecutive VS patients were evaluated. C5S, C6S, VER, and MOBS were evaluated. Spearman's rank correlation coefficients were calculated between the tumor's larger dimension and each of the four parameters for SVN and IVN VS. The nerve of VS origin was identified intraoperatively. To test for differences between CDPP findings of the SVN and IVN groups of VS patients, the Wilcoxon-Mann-Whitney sum rank test was applied. RESULTS: Larger dimension of VS was correlated with C5S and VER in IVN VS patients (r = - 0.358, p=0.008 and r = - 0.356, p=0.008, respectively). Neither C6S nor MOBS showed any significant correlation with the tumor's larger dimension. None of the four scores showed any significant difference between the SVN and IVN groups of VS patients.     

Vestibular evoked myogenic potentials in multiple sclerosis: a comparison between onset and definite cases

Patients affected with multiple sclerosis (MS) frequently suffer from vestibular disorders due to vestibulospinal involvement. The vestibulospinal reflexes in these subjects can be well investigated through vestibular evoked myogenic potentials (VEMPs). Evoked by the acoustic stimulation of the saccular macula and mediated by the vestibulocollic reflex pathway, they are recorded using surface electromyographic electrodes from the ipsilateral sternocleidomastoid muscle tonically contracted. Abnormal findings (e.g., absence of response, prolonged latencies) disclose a lesion anywhere in the pathway. We examined VEMPs in 19 patients with definite MS (5 men, 14 women; age range, 31-59 years; mean age, 45 years) and compared them to VEMPs in 10 subjects with onset MS (2 men, 8 women; age range, 24-35 years; mean age, 29 years). VEMPs in definite MS subjects were abnormal in 14, absent (on the left side only) in 1, and normal in the remaining 4. In patients with onset MS, VEMPs were abnormal in 6. These results suggest that latencies of vestibulospinal reflexes can be remarkably delayed in MS at different stages of disease, whereas vestibulospinal involvement is more frequent in definite cases. To date, no study has yet investigated different VEMPs involvement at different stages of MS.     

Sound-evoked myogenic potentials on the sternocleidomastoid muscle in monkeys

Conclusion. We recorded sound-evoked myogenic potentials of the sternocleidomastoid (SCM) muscle using awake monkeys. The characteristics of these potentials are similar to those of vestibular evoked myogenic potentials (VEMPs) in humans, suggesting that the sound-evoked myogenic potentials of the SCM muscle in monkeys may be utilized as an animal model of VEMPs. Objective: The pathway of the VEMPs remains uncertain as no animal model has yet been used to record sound-evoked myogenic potentials in the SCM muscle. Therefore, the present study aimed to establish an animal model of VEMPs using macaque monkeys. Materials and methods. Four macaque monkeys were used. A pair of electrodes was attached on the SCM muscle ipsilateral side to the intense sound stimulation. Results. The sound-evoked myogenic potentials of the SCM muscle exhibited a biphasic waveform. When a click at 125 dBSPL was applied, the peak latency of the first positive wave was 12.5 ms and was not delayed when the stimulating sound intensity was reduced. The thresholds of the myogenic potentials were 103 dBSPL, which were 43 dB higher than those of the auditory brainstem response (ABR). When a short tone burst was applied, the reactive optimal frequency of the myogenic potentials was relatively low (500–1000 Hz).     

The effect of sternocleidomastoid electrode location on vestibular evoked myogenic potential

OBJECTIVE: The purpose of this study was to investigate the effect of a sternocleidomastoid (SCM) electrode array on the vestibular evoked myogenic potential (VEMP) and the most optimal recording site for clinical use. METHODS: Fifteen normal adults (10 men and 5 women, aged 18 to 38 years) were tested. We placed electrodes at four different locations over the SCM muscle: the upper part of the SCM muscle at the level of mandibular angle, the middle part of the muscle, and immediately above sternal and clavicular origins of the SCM muscle. Sound evoked myogenic potentials in response to monoaurally delivered short tone-bursts (500 Hz at 95 dBnHL, rise/fall time=1 ms and plateau=2 ms) were recorded with surface electrodes over the isometrically contracting SCM muscle. RESULTS: On the clavicle, the upper and middle parts of SCM from all subjects, air-conducted short tone burst evoked biphasic responses (p13-n23). VEMPs recorded at the upper part of the muscle showed the largest amplitude, followed by that at the middle part. However, the latency of the first peaks (p13-n23) was not constant in the upper part. Recording from the middle part of SCM muscle were more consistent. CONCLUSION: Our findings suggest that the middle part of the SCM muscle is the optimal location for recording vestibular evoked myogenic potential.     

Influence of nerve of origin and tumor size of vestibular schwannoma on dynamic posturography findings

Conclusion. Condition 5-score (C5S) and vestibular ratio (VER) correlate, but condition-6-score (C6S) and mean overall balance score (MOBS) do not, with the size of an inferior vestibular nerve (IVN) vestibular schwannoma (VS). In IVN VS patients the visual system plays a major role in the maintenance of postural stability. Objectives. To test whether the size of a superior vestibular nerve (SVN) or IVN VS, as measured on MRI scans, correlates with computerized dynamic platform posturography (CDPP) findings and whether CDPP findings could preoperatively predict the nerve of origin of the VS. Patients and methods. This was a retrospective study. Seventy-five consecutive VS patients were evaluated. C5S, C6S, VER, and MOBS were evaluated. Spearman's rank correlation coefficients were calculated between the tumor's larger dimension and each of the four parameters for SVN and IVN VS. The nerve of VS origin was identified intraoperatively. To test for differences between CDPP findings of the SVN and IVN groups of VS patients, the Wilcoxon-Mann-Whitney sum rank test was applied. Results. Larger dimension of VS was correlated with C5S and VER in IVN VS patients (r?=???0.358, p=0.008 and r?=???0.356, p=0.008, respectively). Neither C6S nor MOBS showed any significant correlation with the tumor's larger dimension. None of the four scores showed any significant difference between the SVN and IVN groups of VS patients.     

The impact of stimulation rates in vestibular evoked myogenic potential testing

Vestibular evoked myogenic potentials (VEMP) have been used in complementary otoneurological assessment, but the use of VEMP in clinical settings is limited. VEMPs can be used to assess vestibular function, particularly of the saccule, the inferior vestibular nerve, and/or the vestibular nucleus.ObjectiveTo verify the highest possible - and reliable - stimulation rate to obtain VEMPs.MethodThe VEMPs of 18 subjects were acquired using stimulation rates ranging between 5.1 and 40.8 stimuli per second. Study design: cross-sectional contemporary cohort study.ResultsLatencies were kept unaltered and amplitudes were progressively reduced as stimulation rates were increased. However, ANOVA and the Kruskal-Wallis test failed to find statistically significant differences between the tested parameters. The study further indicated that when stimulation rates of 5.1 and 10.2 stimuli per second were compared, no statistically significant differences were observed in latency.ConclusionThe highest reliable stimulation rate observed in the group of young adults with normal hearing included in this study was 10.2 stimuli per second.     

Promontory electrical stimulation to elicit vestibular evoked myogenic potentials (VEMPs)

Conclusion: Vestibular evoked myogenic potentials (VEMPs) provoked electrically at the promontory provide a feasible method to record vestibular responses in awake patients. Objectives: Electrically evoked VEMP testing has been performed by galvanic stimulation at the mastoid so far. The present study examined an electrical stimulation mode close to the otolith organs at the promontory. Methods: Fourteen cochlear implant candidates who were planned for clinical routine promontory stimulation testing (PST) to assess auditory nerve function underwent promontory VEMP testing. After testing the cochlear nerve function during PST promontory cervical VEMPs (p-c-VEMPs) and promontory ocular VEMPs (p-o-VEMPs) were recorded during subsequent transtympanic electrical stimulation at the promontory. Results: Promontory VEMP testing was well tolerated by the patients. Mean latencies for p-c-VEMPs were 10.30 ± 2.23 ms (p1) and 17.86 ± 3.83 ms (n1). Mean latencies for p-o-VEMPs were 7.64 ± 1.24 ms (n1) and 11.2 ± 1.81 ms (p1). The stimulation threshold level was measured at 0.15 ± 0.07 mA for p-c-VEMPs and at 0.19 ± 0.11 mA for p-o-VEMPs. The discomfort level was found to be at 0.78 ± 0.29 mA for p-c-VEMPs and at 0.69 ± 0.25 mA for p-oVEMPs. Mean p1-n1 amplitude in p-c-VEMPs was 124.78 ± 56.55 µV and p-o-VEMPs showed a mean n1-p1 amplitude of 30.94 ± 18.98 µV.     

Lesion site in idiopathic bilateral vestibulopathy: a galvanic vestibular-evoked myogenic potential study

CONCLUSION: The result suggests that patients with idiopathic bilateral vestibulopathy may have nerve lesions when the inferior nerve system is affected, while the inferior vestibular nerve system may be spared. OBJECTIVE: To clarify the lesion site in idiopathic bilateral vestibulopathy, an acquired bilateral vestibulopathy of unknown cause. MATERIAL AND METHODS: Two 75-year-old males diagnosed with idiopathic bilateral vestibulopathy were enrolled. Both showed absent or highly decreased responses on the caloric test on both sides. They underwent vestibular-evoked myogenic potential (VEMP) testing by means of acoustical and electrical stimulation. As acoustic stimulation, 95 dB nHL clicks and short tone bursts (500 Hz) were presented, while 3 mA (1 ms) short-duration galvanic stimuli were presented as electrical stimulation. Responses were recorded on the sternocleidomastoid muscles. RESULTS: Both patients showed unilateral absence of VEMPs with both acoustic and short-duration galvanic stimuli.     

Nerve origin of the acoustic neuroma.

Two hundred and seventy-one Japanese patients who underwent surgical removal of neuroma from the cerebello-pontine angle using the translabyrinthine approach were retrospectively reviewed in order to investigate the nerve origin on an anatomical basis. In 269 out of the 271 cases, the origin of the neuromas was identified. Among these cases, 84.8 per cent of tumours originated from the inferior vestibular nerve (IVN), followed by the superior vestibular nerve (SVN) (8.9 per cent). Of the 5.6 per cent of tumours arising from the vestibular nerve, however, it could not be determined whether they originated from the SVN or IVN. Two cases of neuromas originating from the facial nerve were seen (0.7 per cent). No neuroma arose from the cochlear nerve. Currently, the diagnosis of acoustic neuromas is best made with Gd-enhanced magnetic resonance imaging (MRI). However, our data indicate that the development of a functional test of the individual IVN can be useful for screening most cases of acoustic neuroma and in facilitating their early diagnosis.