Reliability of vestibular evoked myogenic potentials in healthy subjects.

OBJECTIVE: To analyze test-retest reliability of vestibular evoked myogenic potential (VEMP) responses with and without the use of electromyography (EMG) monitoring in people with normal audiovestibular function. PATIENTS: Twenty adult volunteers with no history of ear disease, normal otoscopic examination, normal pure-tone audiometry thresholds, and normal tympanograms. INTERVENTIONS: Prospective evaluation of VEMP responses with and without the use of EMG monitoring in 2 separate sessions 1 to 4 weeks apart. MAIN OUTCOME MEASURES: Threshold repeatability, p13 and n23 latency, p13-n23 interlatency, and interamplitude and interaural amplitude difference from the first and the second sessions were assessed via the intraclass correlation coefficient. RESULTS: Test-retest reliability of p13-n23 interamplitude was found to be excellent, and the reliability of threshold and latency was found to be fair to good (with the exception of poor reliability for p13 latency in the EMG monitoring condition). CONCLUSION: Overall, VEMP response parameters were found to have fair to good test-retest reliability. The intraclass correlation coefficient value for amplitude was found to be more reliable than latency, with the latency of n23 more reliable than the latency of p13. Clinicians should consider these findings when interpreting VEMP responses. Maintenance of symmetric head rotation with and without EMG monitoring produced reliably reproducible results, the VEMP amplitude being the best criteria.     

Effects of stimulus conditions on vestibular evoked myogenic potentials in healthy subjects

Background: Characteristics of vestibular evoked myogenic potentials (VEMPs) depend on stimulus conditions.

Objective: To determine the optimal stimulus conditions for cervical and ocular VEMPs.

Methods: Participants were 23 healthy subjects. We compared air-conducted cervical and ocular VEMPs elicited by various tone-burst conditions (frequencies 500–1,000?Hz, rise/fall times 1–2?ms, and plateau times 0–6?ms) with an intensity of 105?dB normal hearing level. Effects of simultaneous contralateral masking noise on VEMPs were also evaluated.

Results: The largest cervical VEMP amplitudes were elicited by 500–750?Hz and 2–6?ms plateau time-tone-bursts, and the largest ocular VEMP amplitudes by 750?Hz and 2–4?ms plateau time-tone-bursts. Repeatability of the latency was better at 1?ms than at 2?ms rise/fall time in both VEMPs. In both VEMPs, masking noise reduced amplitude, and in ocular VEMP, amplitudes were significantly larger at the left ear stimulation than the right.

Conclusion: Optimal tone-burst stimulation for both VEMPs seemed to be 500–750?Hz frequency and 1/2/1?ms rise/plateau/fall time without contralateral masking noise. Ocular VEMP amplitudes from left ear stimulation were originally larger than those from right ear stimulation.     

Induced vestibular myogenic potentials in healthy subjects

The present study included 23 healthy men examined by the method of evoked vestibular myogenic potentials. The normal values of parameters of representativeness were determined, the median was 0.95, the 25th and 75th percentiles were 0.88 and 0.97 respectively. The values of P1 peak latency varied from 10 to 13.4 ms, NI peak from 14.67 to 25 ms, the PINI segment from 4.33 to 13.67 ms. The amplitude of peaks P1, N1, P1N1 changed from 3.76 to 190 mcV. The variability of responses did not exceed 14% in terms of latency and 21% in terms of amplitude.     

Clinical application of vestibular evoked myogenic potentials in healthy newborns

OBJECTIVE: Auditory and vestibular functions have critical importance in infancy because they may affect motor and mental development. We aimed to determine the normal values of the vestibular evoked myogenic potential (VEMP) parameters to provide a reference for further research regarding the early diagnosis of vestibular dysfunction in newborns. METHODS: Twenty-four term newborns (12 girls, 12 boys), with birth weights greater than 2500 g and Apgar scores higher than 7 at 1 min, were studied. Tympanometry, auditory-evoked brainstem responses, transient-evoked otoacoustic emissions, and VEMP recordings were assessed in all subjects during fourth week after birth. RESULTS: All newborns passed the audiologic evaluation, and biphasic waveforms of the VEMP were obtained in all 48 tested ears. Mean latencies of p13, n23, and p13-n23 intervals were 13.7+/-1.1, 20.5+/-1.6, and 7.1+/-2.1 ms, respectively. The mean amplitude value was 22.6+/-18.4 microV. There were no significant differences in latency values or amplitudes with regard to sex or side of ear tested in newborns. CONCLUSIONS: VEMP may easily be used for early evaluation of vestibular dysfunction in newborns. Because results may differ owing to test techniques and age, every laboratory should have its own normal values.     

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.     

Evaluation of vestibular evoked myogenic potentials

In previous studies, electromyographic potentials, recorded in response to auditory clicks, have been attributed to stimulation of the otolith (saccule) and have been termed vestibular evoked myogenic potentials (VEMPs). In this study, we assessed the VEMPs in subjects with normal auditory brainstem evoked responses, with no history of vestibular symptoms or neck and other skeletal muscle abnormalities. To this effect, 32 subjects (64 ears), after ethics committee approval, were exposed to 75, 150, and 300 clicks at 100 dB, and the responses were averaged. Electromyographic activity was recorded by applying surface electrodes over the sternocleiodomastoid muscle under the following three conditions: no muscle contraction/no clicks, muscle contraction/no clicks, and muscle contraction/clicks. Our findings suggest that electromyographic responses have to be obtained, during muscle contraction, first without and then with clicks. Our data also suggest that comparison of these two recordings is necessary for meaningful results.     

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.     

Age-related changes in vestibular evoked myogenic potentials

Vestibular evoked myogenic potentials (VEMP) in response to sound stimulation (500 Hz tone burst, 129 dB SPL) were studied in 1000 consecutive patients. VEMP from the ear with the larger amplitude were evaluated based on the assumption that the majority of the tested patients probably had normal vestibular function in that ear. Patients with known bilateral conductive hearing loss, with known bilateral vestibular disease and those with Tullio phenomenon were not included in the evaluation. It was found that there was an age-related decrease in VEMP amplitude and an increase in VEMP latency that appeared to be rather constant throughout the whole age span. The VEMP data were also compared to an additional group of 10 patients with Tullio phenomenon. Although these 10 patients did have rather large VEMP, equally large VEMP amplitudes were observed in a proportion of unaffected subjects of a similar age group. Thus, the finding of a large VEMP amplitude in response to a high-intensity sound stimulation is not, per se, distinctive for a significant vestibular hypersensitivity to sounds.     

Cervical vestibular evoked myogenic potentials in children

IntroductionCervical vestibular evoked myogenic potential is a test used in neurotological examination. It verifies the integrity of vestibular function through a muscular response evoked by an acoustic stimulation which activates the saccular macula. Normal standards in adults have been established, however, there are few published data on the normal responses in children.ObjectiveTo establish normal standards for vestibular myogenic responses in children without neurotological complaints.MethodsThis study's design is a cohort with cross-sectional analysis. The sample consisted of 30 subjects, 15 females (50%) and 15 males (50%).ResultsThe age of the subjects ranged between 8 and 13 years, with a mean of 10.2 (± 1.7). P1 peak showed an average latency of 17.26 (± 1.78) ms and a mean amplitude of 49.34 (± 23.07) μV, and the N2 peak showed an average latency of 24.78 (± 2.18) ms and mean amplitude of 66.23 (± 36.18) μV. P1–N2 mean amplitude was 115.6 (± 55.7) μV. There were no statistically significant differences when comparing by gender or by laterality.ConclusionWe established normal values of cervical myogenic vestibular responses in children between 8 and 13 years without neurotological complaints.     

前庭诱发的肌源性电位临床应用

前庭诱发的肌源性电位（Vestibular evoked myogenic potentials，VEMP）可用于评价球囊功能及其对称性。本文总结VEMP在神经耳科学中的应用情况。首先建立VEMP的临床适用的检查方法，这些方法包括：刺激声的选择、刺激强度及给声方式，建立VEMP在振幅、阈值、潜伏期和耳间潜伏期的正常值。临床上常用于：梅尼埃病和迟发性膜迷路积水、前庭神经炎、听神经瘤、前半规管裂综合征和听神经病的诊断定位。VEMP的振幅变化较大．潜伏期的变化较大，而阈值较稳定。梅尼埃病和迟发性膜迷路积水、前庭神经炎、听神经瘤可以出现振幅的异常或引不出；梅尼埃病、迟发性膜迷路积水和听神经瘤可见振幅和潜伏期异常。听神经瘤还可见耳间潜伏期延长。听神经病主要表现为振幅的异常，振幅减低或引不出。VEMP是一种稳定的肌源性电位，双侧声刺激较为适宜。VEMP的阈值检查主要用于压力或声音敏感性眩晕；耳间潜伏期的异常主要见于桥一小脑角占位病变：振幅和潜伏期的异常一般没有特异性．可见于累及前庭下神经的病变。     

直流电刺激诱发健康青年人前庭诱发肌源性电位的初步观察

目的 介绍直流电刺激诱发的前庭诱发肌源性电位(galvanic vestibular stimulation-vestibular evoked myogenic potentials,GVS-VEMP)的测试方法,观察我国健康青年人直流电刺激诱发的颈肌前庭诱发肌源性电位(cervical vestibular evoked myogenic potentials,cVEMP)和眼肌前庭诱发肌源性电位(ocular vestibular evoked myogenic potentials,oVEMP)的引出情况并分析相关参数.方法 选择26名健康青年志愿者作为研究对象,其中女13名(26耳),男13名(26耳);年龄21~37岁,平均(25.8±3.7)岁.初始刺激使用3.0 mA/1 ms的直流电(阴极)刺激乳突,分别于胸锁乳突肌和眼下肌记录直流电刺激诱发的颈肌前庭诱发肌源性电位(GVS-cVEMP)和直流电刺激诱发的眼肌前庭诱发肌源性电位(GVS-oVEMP).刺激强度逐次递减直至不能诱发出稳定的波形,计算GVS-VEMP反应的阈值、潜伏期、波间期、振幅和振幅不对称比.采用SPSS 18.0软件进行统计学分析.结果 26名(52耳)健康青年志愿者在3.0 mA/1 ms的直流电刺激下,均可引出GVS-cVEMP和GVS-oVEMP,引出率为100%.随着刺激强度的减弱,二者的引出率均下降.GVS-cVEMP的阈值为(1.18±0.47)mA,p1潜伏期为(10.43±1.54)ms,n1潜伏期为(17.91±1.20)ms,振幅为(102.47±56.77)uV,振幅不对称比0.26±0.20;GVS-oVEMP的阈值为(1.12±0.50)mA,n1潜伏期为(8.46±1.05)ms,p1潜伏期为(11.83±1.27)ms,振幅(9.12±6.82)uV,振幅不对称比0.25±0.20.GVS-oVEMP振幅男性高于女性,差异有统计学意义(P<0.05);GVS-cVEMP和GVS-oVEMP其他参数在性别和侧别比较上,差异均无统计学意义(P值均>0.05).结论 健康青年人可稳定诱发出GVS-cVEMP和GVS-oVEMP反应,其相应波形参数可为后续前庭功能评估提供参考.     

Age-related differences in parameters of vestibular evoked myogenic potentials

Conclusions. The statistically significant correlations between vestibular evoked myogenic potential (VEMP) parameters and age may be due to hair cell loss of the otolith organ and/or to degenerative changes of the vestibular neural pathway. These findings indicate that age should be taken into account when interpreting VEMP results. It is also important to determine a standard method for performing VEMP and a universal index for comparison among laboratories. Objectives. VEMP, which measures the surface electric potential from the cervical muscle evoked by sufficiently loud sounds, is a useful tool to evaluate vestibule-colic reflex function. We have assayed the effect of age on VEMP results. Subjects and methods. After excluding subjects with a previous history of dizziness, middle ear pathology, or other inner ear symptoms, a total of 97 healthy volunteers (194ears) were included. All VEMP parameters were analyzed to find differences related to side and gender, as well as the relationship between age and each VEMP parameter. Results. Age was correlated with all VEMP parameters. Latency of p13, n23 showed a negative correlation and amplitude of p13-n23 showed a positive correlation with age. Differences between the right and left sides were not significant.     

Development of vestibular evoked myogenic potentials in preterm neonates

Our recent study successfully recorded vestibular evoked myogenic potential (VEMP) responses in full-term newborns. However, when VEMP responses are elicited in preterm neonates remains unclear. This study employed the VEMP test in 27 low-risk preterm and 25 healthy full-term neonates without sedation to investigate the development of VEMP response after birth. Fourteen (26%) of 54 ears in preterm neonates exhibited VEMP responses, a response rate significantly lower than that of full-term neonates (72%). The mean latencies of peaks p13 and n23 in the preterm group were significantly longer than those in the full-term group. Analysis of variable parameters for present VEMPs in pre- and full-term neonates revealed that the cutoff values of body weight were 2.26 and 2.82 kg, and that those of postmenstrual age were 37.1 and 38.4 weeks, respectively. Both body weight and postmenstrual age were significantly negatively correlated with p13 and n23 latencies but not with p13-n23 amplitude. In conclusion, present VEMPs can be anticipated when the body weight of pre- and full-term neonates reaches >2.26 and 2.82 kg, respectively. It indicates that the sacculocollic reflex develops in the same manner, but the difference in response rate between full- and pre-term neonates may, at least in part, correlate with muscle bulk and strength, relative to the body weight adequate for the VEMP response.     

Glycerol affects vestibular evoked myogenic potentials in Meniere's disease

OBJECTIVES: to show that abnormal vestibular evoked myogenic potentials on the sternocleidomastoid muscle (SCM) in patients with unilateral Meniere's disease are caused by endolymphatic hydrops. Subjects: six normal volunteers and 17 patients with unilateral Meniere's disease were examined. METHODS: click-evoked myogenic potentials were recorded with surface electrodes over each SCM. Responses evoked by clicks recorded after oral administration of glycerol (1.3 g/kg body weight) were compared with those recorded before administration. RESULTS: the change rate of the p13-n23 amplitude was calculated. The mean+standard deviation (S.D.) of the change rate was 3.52+14.6% in normal subjects. On the unaffected side of patients the change rates were within the normal range (within the mean+/-2S.D.) in 13 patients, and three ears showed significant decrease. Only one ear showed significant increase. On the affected side, five ears showed significant increase of the amplitude while two ears showed significant decrease after oral administration of glycerol. Effects on evoked myogenic potentials were independent of those on pure tone hearing. CONCLUSION: vestibular evoked myogenic potentials in some patients with unilateral Meniere's disease were improved by oral administration of glycerol. This result suggests that abnormal vestibular evoked myogenic potentials in patients with unilateral Meniere's disease could result from endolymphatic hydrops.     

Changes in vestibular evoked myogenic potentials after Meniere attacks

OBJECTIVES: The aim of this study was to apply videonystagmography (VNG) and vestibular evoked myogenic potential (VEMP) tests to patients with Meniere attacks, to explore the mechanics of where saccular disorders may affect the semicircular canals. METHODS: From January 2001 to December 2003, 12 consecutive patients with unilateral definite Meniere's disease with vertiginous attacks underwent VNG for recording spontaneous nystagmus, as well as VEMP tests. RESULTS: At the very beginning of the Meniere attack, the spontaneous nystagmus beat toward the lesion side in 5 patients (42%) and toward the healthy side in 7 patients (58%). Twenty-four hours later, only 6 patients (50%) showed spontaneous nystagmus beating toward the healthy side. Nevertheless, spontaneous nystagmus subsided in all patients within 48 hours. The VEMP test was performed within 24 hours of a Meniere attack; the VEMPs were normal in 4 patients and abnormal in 8 patients (67%). After 48 hours, 4 patients with initially abnormal VEMPs had resolution and return to normal VEMPs, and the other 4 patients still had absent VEMPs. CONCLUSIONS: Most patients (67%) with Meniere attacks revealed abnormal VEMPs, indicating that the saccule participates in a Meniere attack. This is an important idea that stimulates consideration of the mechanism of Meniere attacks.     

Characterizing the frequency tuning properties of air-conduction ocular vestibular evoked myogenic potentials in healthy individuals

Abstract

Objective: Inconsistencies regarding frequency tuning of ocular vestibular evoked myogenic potentials (oVEMP) prompted the present study to aim at characterizing frequency tuning of oVEMP in healthy individuals. Design: Normative study. Study sample: The study was conducted to obtain oVEMP responses from 54 healthy individuals in age range of 18–30 years. The responses were acquired for tone-bursts at octave and mid-octave frequencies from 250 to 2000 Hz from the inferior oblique muscle using contralateral electrode placement. The frequencies were compared for amplitude and threshold. Results: oVEMPs were present in 100% of individuals at or below the frequency of 1000 Hz. The responses had maximum amplitude and lowest thresholds at 500 Hz. There were at least two replicable peak-complexes namely n1-p1 and p1-n2. Both these complexes revealed tuning at 500 Hz. Comparison between the two peak-complexes revealed higher amplitudes and lower thresholds for p1-n2 complex. Conclusions: oVEMPs are tuned to 500 Hz for both peak-complexes, with p1-n2 being more robust. Future studies using the threshold of oVEMP may be better suited to use p1-n2 complex for this purpose, provided vestibular origin of the second complex is proved. Additionally, careful use of tuning property is recommended when evaluating pathological conditions.