Ocular vestibular evoked myogenic potentials produced by impulsive lateral acceleration in unilateral vestibular dysfunction

Objective

To deduce the connectivity underlying ocular vestibular evoked myogenic potentials (OVEMPs) recorded from two sites and produced by lateral transmastoid stimulation in patients with unilateral vestibular dysfunction.

Methods

OVEMPs were recorded using lateral impulsive stimuli delivered by a hand-held minishaker placed at the mastoid. Twelve patients were tested using the typical OVEMP recording montage placed inferior to the eyes. In a subset of 6 patients, recordings were also made using a lateral electrode montage. The majority of patients were tested following surgery for inner ear disease. Patient responses were compared to those in normal subjects under similar recording conditions.

Results

For the inferior montage, regardless of which mastoid was stimulated, deficits were observed only from the eye opposite the affected ear. In contrast, OVEMPs recorded using the lateral electrode montage showed changes on both sides.

Conclusions

OVEMPs produced using lateral transmastoid stimulation and recorded from beneath the eyes are generated by a crossed vestibulo-ocular pathway while the projections underlying the lateral responses are likely to be bilateral.

Significance

The vestibular-ocular connectivity underlying the OVEMPs recorded from inferior and lateral recording sites differs. For clinical use, the inferior recording site is the simplest to interpret.     

Differing response properties of cervical and ocular vestibular evoked myogenic potentials evoked by air-conducted stimulation

ObjectiveTo determine the amplitude changes of vestibular evoked myogenic potentials (VEMPs) recorded simultaneously from the neck (cVEMPs) and eyes (oVEMPs) in response to 500 Hz, 2 ms air-conducted sound pips over a 30 dB range.MethodsFifteen healthy volunteers (mean age 29, range 18–57 years old) and one patient with unilateral superior canal dehiscence (SCD) were studied. The stimulus was reduced in increments to 105 dB pSPL for the normals (81 dB pSPL for the SCD patient). A statistical criterion was used to detect responses.ResultsIpsilateral (i-p13/n23) and contralateral (c-n12/p24/n30) peaks for the cVEMP montage and contralateral (c-n10/p16/n21) and ipsilateral (i-n13) peaks for the oVEMP montage were present for the baseline intensity. For the lowest intensity, 6/15 subjects had responses for the i-p13 cVEMP potential and 4/15 had c-n10 oVEMP responses. The SCD patient showed larger responses for nearly all intensities. The cVEMP potentials were generally well fitted by a power law relationship, but the oVEMP c-n10, p16 and n21 potentials showed a significant increase in gradient for the higher intensities.ConclusionMost oVEMP and cVEMP responses follow a power law relationship but crossed oVEMP responses showed a change in gradient above a threshold.SignificanceThe pattern of response to AC stimulation may be a property of the pathways underlying the potentials.     

Brainstem representation of vestibular evoked myogenic potentials

ObjectiveVestibular evoked myogenic potentials (VEMPs) are caused by a short-latency reflex recorded from averaged electromyography from the sternocleidomastoid muscle evoked by intense auditory clicks. Besides peripheral vestibulopathy, abnormal VEMPs can be caused by lesions of the brainstem. The aim of this study was to analyze the topology of ischemic brain lesions generating pathological VEMPs.MethodsTwenty-nine patients with brainstem infarcts were prospectively studied using VEMPs and MR imaging to evaluate the brainstem representation of the VEMP reflex. Individual brainstem lesions were projected to a standard MR-dataset for normalization. Probabilistic lesion maps were calculated. A digital brainstem atlas was fitted to the lesion maps.ResultsTwelve patients showed unilaterally abnormal VEMPs, 10 patients had normal VEMPs. Seven patients with bilaterally absent VEMPs were not analyzed. Most lesions were located in the lateral medulla oblongata involving the spinal accessory nerve. Most lesions in the pons were associated to anterolateral parts of pyramidal tract fibers. In a few cases, lesions were located in the tegmental area of the pons, including the vestibular nuclei.ConclusionsAbnormal VEMPs may be produced not only by peripheral vestibulopathy but also by brainstem lesions. VEMPs may be influenced by effects caused by lesions located above the level of the vestibular nuclei.SignificanceThis study adds to the knowledge of anatomical brainstem representation of VEMP.     

Feasibility of the simultaneous ocular and cervical vestibular-evoked myogenic potentials in unilateral vestibular hypofunction

ObjectiveThis study compared the results of combined and individual ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in healthy subjects and patients with unilateral vestibular hypofunction to confirm the effectiveness of the combined oVEMP and cVEMP test.MethodsTwenty healthy volunteers and 12 patients with unilateral vestibular hypofunction underwent individual oVEMP and cVEMP tests in a random order, and combined oVEMP and cVEMP test on another day.ResultsTwenty healthy subjects had 100% response rates for oVEMPs and cVEMPs in both individual and combined stimulation modes. Significant positive correlations exist between individual and combined oVEMPs/cVEMPs in terms of latencies and amplitudes. In 12 patients with unilateral vestibular hypofunction, differences in abnormal percentages of oVEMPs or cVEMPs were non-significant. Additionally, the characteristic parameters of oVEMP/cVEMP among ears of healthy subjects, good and pathological ears of patients with unilateral vestibular hypofunction did not differ significantly, regardless of whether the individual or combined mode was used.ConclusionsThe combined oVEMP and cVEMP test generates similar information to that obtained by individual mode, regardless of whether subjects are healthy or have unilateral vestibular hypofunction.SignificanceSimultaneous oVEMP and cVEMP tests may be a convenient screening tool for assessing crossed vestibulo-ocular reflex and ipsilateral sacculo-collic reflex, which definitely shortens the diagnostic test time. Thus, it may favor the large diffusion of these techniques.     

前庭阵发症前庭诱发肌源性电位的特征及应用

目的观察前庭阵发症(vestibular paroxysmia,VP)患者前庭诱发肌源性电位(vestibular evoked myogenic potentials,VEMPs)的引出率和各参数指标,探讨其临床诊断及应用价值。方法将20例伴有神经血管交互压迫(neurovascular cross compression,NVCC)的VP患者作为VP组,并以同期20例年龄、性别分布相仿磁共振检查未见NVCC的健康体检者作为对照组。对所有入组者行眼肌前庭诱发电位(ocular vestibular evoked potential,o VEMP)和颈肌前庭诱发电位(cervical vestibular evoked potential,c VEMP)检查,对其VEMPs的引出率和各参数进行组间和组内比较,进一步对VP的VEMPs特点进行分析。结果 (1) VP组o VEMP引出22耳(55%),其非NVCC侧引出16耳(84. 21%)、NVCC侧6耳(28. 57%),差异具有统计学意义(χ~2=10. 33,P 0. 05),对照组引出35耳(87. 50%); VP组c VEMP引出26耳(65%),其中非NVCC侧引出17耳(89. 47%),NVCC侧9耳(42. 86%),差异具有统计学意义(χ~2=7. 59,P 0. 05),对照组引出35耳(87. 50%); VP组NVCC侧与对照组o VEMP、c VEMP引出率经组间比较,差异均具有统计学意义(χ~2=21. 70,P 0. 05;χ~2=13. 65,P 0. 05); VP组非NVCC侧与对照组o VEMP、c VEMP引出率经组间比较,差异均无统计学意义(χ~2=0. 00,P 0. 05;χ~2=0. 00,P 0. 05)。(2)在VP组,c VEMP与o VEMP引出率比较,差异无统计学意义(χ~2=0. 83,P 0. 05)。(3) VP组NVCC侧潜伏期延长、振幅下降,与非NVCC侧VEMPs各参数值经组内比较,差异均有统计学意义(P值均0. 05); VP组NVCC侧与对照组VEMPs各参数值经组间比较,差异均有统计学意义(P值均0. 05); VP组非NVCC侧与对照组VEMPs各参数值经组间比较,差异均无统计学意义(P值均0. 05)。结论 VP患者NVCC侧VEMPs引出率较低、潜伏期延长、振幅下降,NVCC是VP的发病机制之一且VEMPs有助于鉴别病变侧; VP患者NVCC侧前庭上、下神经传导通路均有一定的异常。     

Ocular vestibular evoked myogenic potentials to head tap and cervical vestibular evoked myogenic potentials to air-conducted sounds in isolated internuclear ophthalmoplegia

ObjectiveThe central pathways responsible for ocular vestibular evoked myogenic potentials (VEMPs) to forehead tapping remain to be determined. This study aimed to determine whether the medial longitudinal fasciculus (MLF) carries the signals for ocular VEMPs (oVEMPs) in response to this mode of stimulation.MethodsTwelve patients with isolated unilateral internuclear ophthalmoplegia (INO) due to brainstem infarction underwent evaluation of the ocular tilt reaction (ocular torsion and skew deviation), tilt of the subjective visual vertical (SVV), cervical VEMPs (cVEMPs) in response to tone burst sound, and oVEMPs induced by tapping the forehead.ResultsEight (67%) patients showed abnormal oVEMPs that included no wave formation (n = 4) and decreased amplitude (n = 3) in the lesion side, and bilaterally absent responses in the remaining patient. Furthermore, the patients showed diminished oVEMPs responses in the lesion side compared with normal side (6.0 ± 5.6 vs. 11.7 ± 5.5 μV, paired t-test, p = 0.001) and increased IAD_amp(%) of the oVEMPs compared with normal controls (43.6 ± 41.2 vs. 9.1 ± 6.2, t-test, p = 0.018). In contrast, cVEMPs were abnormal in only three (25%) patients, decreased (n = 2) or no response in the lesion side. Eleven (92%) patients showed contraversive ocular tilt reaction or SVV tilt.ConclusionPatients with INO frequently show impaired formation of ipsilesional oVEMPs in response to forehead tapping. The occasional abnormality and decreased amplitude of ipsilesional cVEMPs also suggest a modulatory pathway for the inhibitory sacculocollic reflex descending in the MLF.SignificanceThis study suggests that the MLF contains the fibers for the otolith-ocular reflex from the contralateral ear.     

Recovery of ocular and cervical vestibular evoked myogenic potentials after treatment of inner ear diseases

Abstract

Purpose: This study aimed to assess the clinical value of ocular vestibular evoked myogenic potential (oVEMP) and cervical vestibular evoked myogenic potential (cVEMP) for monitoring the rehabilitation of vestibular function in patients treated for peripheral vertigo.

Materials and methods: Fifteen patients who had been diagnosed with peripheral vertigo and showed no VEMP response on the affected side but exhibited symptom alleviation and VEMP responses after therapies were retrospectively enrolled. We analyzed the restoration and parameters of their VEMP response.

Results: After treatment, six patients with sudden sensorineural hearing loss showed VEMP recovery, including two with both oVEMP and cVEMP recovery, three with oVEMP recovery only, and one with cVEMP recovery only. Two patients with Meniere’s disease (MD) showed cVEMP recovery, while the other three MD patients showed oVEMP recovery. Three patients with herpes zoster oticus exhibited cVEMP recovery. One patient with vestibular neuritis exhibited cVEMP recovery. Among the patients with cVEMP and/or oVEMP restoration, most patients presented normal VEMP parameters; however, some patients showed abnormal VEMP parameters after treatment.

Conclusion: Combined oVEMP and cVEMP are objective tools for assessing vestibular otolithic end organ function during dynamic functional recovery from vestibular diseases.     

Frequency-tuning characteristics of cervical and ocular vestibular evoked myogenic potentials induced by air-conducted tone bursts

ObjectiveTo better characterize both ocular and cervical vestibular evoked myogenic potentials (VEMP) responses at different frequencies of sound in 20 normal subjects.MethodsCervical and ocular VEMPs were recorded. The intensities of sound stimulation decreased from the maximal intensity, until no responses were evoked. Thresholds, amplitudes, latencies and interaural amplitude difference ratio (IADR) at the maximal stimulation were calculated.ResultsBoth tests showed the similar frequency tuning, with the lowest threshold and highest amplitude for 500-Hz tone-burst stimuli. Sound stimulation at 500 Hz showed the response rates of 100% in both tests. Cervical VEMPs showed higher incidence than ocular VEMPs. Ocular VEMP thresholds were significantly higher than those of cervical VEMP. Cervical VEMP amplitudes were significantly higher than ocular VEMP amplitudes. IADRs of ocular and cervical VEMPs did not differ significantly.ConclusionsOcular VEMP showed the similar frequency tuning to cervical VEMP. Cervical VEMP responses showed higher incidence, lower thresholds and larger amplitudes than ocular VEMP.SignificanceCervical VEMP is a more reliable measure than ocular VEMP, though the results of both tests will be complementary. Five hundred Hertz is the optimal frequency to use.     

The effect of alcohol on cervical and ocular vestibular evoked myogenic potentials in healthy volunteers

ObjectiveWe investigated the effect of alcohol on the cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs). As alcohol produces gaze-evoked nystagmus (GEN), we also tested the effect of nystagmus independent of alcohol by recording oVEMPs during optokinetic stimulation (OKS).MethodsThe effect of alcohol was tested in 14 subjects over multiple rounds of alcohol consumption up to a maximum breath alcohol concentration (BrAC) of 1.5‰ (mean 0.97‰). The effect of OKS was tested in 11 subjects at 5, 10 and 15 deg/sec.ResultsoVEMP amplitude decreased from baseline to the highest BrAC level by 27% (range 5–50%, P < 0.001), but there was no significant effect on oVEMP latency or cVEMP amplitude or latency. There was a significant negative effect of OKS on oVEMP amplitude (16%, P = 0.006).ConclusionsWe found a selective effect of alcohol on oVEMP amplitude, but no effect on the cVEMP. Vertical nystagmus elicited by OKS reduced oVEMP amplitude.SignificanceAlcohol selectively affects oVEMP amplitude. Despite the effects of alcohol and nystagmus, both reflexes were reliably recorded in all subjects and conditions. An absent response in a patient affected by alcohol or nystagmus indicates a vestibular deficit.     

Cervical and ocular vestibular-evoked myogenic potentials in acute vestibular neuritis

ObjectivesTo clarify the origin and afferent pathways of short-latency ocular vestibular-evoked myogenic potential (oVEMP) in response to air-conducted sound (ACS), we evaluated cervical (cVEMP) and ocular VEMPs in patients with vestibular neuritis (VN).MethodsIn response to air-conducted tone burst, the oVEMP and cVEMP were measured in 60 healthy controls and in 41 patients with acute VN. The VN selectively involved the superior vestibular nerve (superior VN) in 30 patients, affected the inferior vestibular nerve only (inferior VN) in three and damaged both superior and inferior vestibular nerve branches in eight.ResultsAll 30 patients with superior VN presented normal cVEMPs, indicating preservation of the saccular receptors and their afferents in the inferior vestibular nerve. However, the oVEMP was abnormal in all patients with superior VN. By contrast, the patients with inferior VN showed normal oVEMP and abnormal cVEMP.ConclusionThese dissociations in the abnormalities of cVEMP and oVEMP in patients with VN selectively involving the superior or inferior vestibular nerve suggest that the origin of the vestibular nerve afferents of oVEMP differ from those of cVEMP.SignificanceThe oVEMP in response to ACS may be mediated by the superior vestibular nerve, probably due to an activation of the utricular receptors.     

Cervical vestibular evoked myogenic potentials in primary headache disorders

ObjectiveTo determine if cervical vestibular evoked myogenic potentials (cVEMPS) differ in patients with migraine without aura (MoA), vestibular migraine (VM) and tension type headache (TTH).MethodsTwenty patients with MoA, 24 patients with VM and 20 patients with TTH were included in the study. Thirty healthy volunteers of comparable age and gender were taken as the control group. The latencies of peaks p13 and n23, peak-to-peak amplitude of p13–n23 divided by a mean prestimulus EMG recorded during cVEMP testing were measured. The amplitude asymmetry between right and left sides was also calculated and taken into consideration. Caloric testing was conducted to check if the results are associated with the results of the cVEMPs.ResultsFive (one on the right, four on the left side) of the 24 patients with VM (20.8%) displayed a unilateral caloric hypofunction. Normal results were recorded from patients with MoA and TTH. p13, n23 latencies and amplitudes of the patient groups were not statistically different from the results of the healthy controls (p > 0.05). An amplitude asymmetry between right and left sides exceeding that of the healthy controls was not also present (p > 0.05).ConclusionsThough a hypofunctioning horizontal semicircular canal was detected in 20.8% of the patients with VM, saccular function seemed to be unaffected. Patients with MoA and TTH did not display any vestibular test abnormality.SignificancePrimary headache disorders seem to be associated with a normal interictal cVEMP profile.     

Ocular and cervical vestibular evoked myogenic potentials in multiple sclerosis patients

ObjectiveVestibular evoked myogenic potentials (VEMPs) are thought to provide useful information about brainstem functions, as the neural pathways of both ocular and cervical VEMPs pass through the brainstem. The aim of this study was to investigate the clinical value of ocular and cervical VEMP tests in the evaluation of brainstem involvement in multiple sclerosis (MS) patients and to assess their relation with clinical and cranial MRI findings.MethodsOcular and cervical VEMPs were recorded in 62 MS patients and 35 age and sex matched healthy volunteers. The latencies, amplitude asymmetry ratios of both VEMP responses and abnormality ratios (prolonged latencies and absent responses) were compared between the MS patients and the control group and among the groups of MS patients.ResultsoVEMP mean n1 and p1 latencies and cVEMP mean p13 latency were significantly prolonged in MS patients. Although the abnormality ratios of both VEMPs were higher in patients with brainstem clinical or MRI lesions, the correlation was not statistically significant. Both ocular and cervical VEMP latencies were significantly correlated with expanded disability status scale.ConclusionsAlthough there is no significant correlation with clinical or MRI findings, MS patients show high frequency of abnormality in VEMP tests, especially in oVEMP tests.SignificanceVEMP tests may be useful as an adjunct test in the evaluation of brainstem dysfunction in MS patients.     

多发性硬化患者前庭诱发肌源性电位的临床意义

目的研究多发性硬化(multiple sclerosis,MS)患者前庭诱发肌源性电位(vestibularevoked myogenic potentials,VEMPs)各参量的变化及临床意义,比较VEMPs与核磁共振、脑干听觉诱发电位对MS病变的检测能力。方法采用双耳短声刺激记录37例MS患者(有脑干症状21例、无脑干症状16例)和20名健康对照的VEMPs的潜伏期和振幅值,计算双侧在13ms左右出现的正波(p13)波幅潜伏期差值(Δp13)和振幅比(SR)。37例MS患者均做核磁共振成像,其中33例记录脑干听觉诱发电位。结果有脑干症状组和对照组相比,p13潜伏期显著延长[左侧为(13.84±2.57)ms和(12.20±1.10)ms,P<0.05;右侧为(14.69±2.96)ms和(12.10±2.60)ms,P<0.01],Δp13显著增大(1.63±1.82和1.00±1.44,P<0.01),而无脑干症状组差异无统计学意义。两组MS患者的p13-n23(在23ms左右出现的负波)振幅值与对照组相比均降低[左侧分别为(149.98±52.2)、(175.51±49.22)、(272.80±165.81)μV;右侧分别为(156.88±97.04)、(167.74±57.32)、(257.50±138.49)μV,P均<0.05],扩展的残疾功能量表评分与振幅有相关性(左侧r=0.45,右侧r=0.46,P均<0.05)。VEMPs与核磁共振相比,对病灶的检出率低(分别为33%与100%,P<0.05),与脑干听觉诱发电位相比差异无统计学意义。结论p13潜伏期及Δp13可作为判定MS前庭脊髓通路脱髓鞘的参考指标。VEMPs作为辅助诊断MS的一项新的诱发电位,对脑干病灶的诊断有一定临床参考意义。     

Measuring neck structures in relation to vestibular evoked myogenic potentials.

OBJECTIVE: This study examined whether neck length or thickness influences vestibular evoked myogenic potential (VEMP) responses. METHODS: Twenty healthy children and 20 healthy adults underwent VEMP testing. Two reference points were selected for measuring neck length. Maximum thickness of the subcutaneous tissue and the sternocleidomastoid muscle was measured by ultrasonographic examination. RESULTS: The mean latencies of peaks p13 and n23 in 20 healthy children were significantly earlier than those in healthy adults. Neck length significantly related to p13 latency in children, but not in adults. In contrast, corrected amplitudes did not differ significantly between children and adults. Ultrasonography guided measurement of the subcutaneous thickness in adults associated negatively with raw amplitude, but not with corrected amplitude. CONCLUSIONS: Vestibular evoked myogenic potential latencies correlated positively to neck length in all subjects (children and adults), while raw amplitudes of VEMPs in adults correlated negatively with subcutaneous thickness. No correlation between neck thickness and corrected amplitude was observed. SIGNIFICANCE: Structural differences affecting latencies and raw amplitudes of VEMP responses should be considered when interpreting VEMP parameters.