Prediction of the nerves of origin of vestibular schwannomas with vestibular evoked myogenic potentials

OBJECTIVE: To determine whether the nerves of origin of vestibular schwannomas can be predicted using vestibular evoked myogenic potentials (VEMPs). STUDY DESIGN: The study was a retrospective analysis. SETTING: The ear, nose, and throat department of Tokyo Medical and Dental University. PATIENTS: Twenty-eight patients undergoing removal of vestibular schwannomas were included in the study. INTERVENTIONS: Patients underwent pure tone audiometry, VEMP testing, caloric testing, and magnetic resonance imaging preoperatively. Hearing level, caloric weakness, maximum tumor size, and the nerves of origin of tumors were compared with VEMP testing. MAIN OUTCOME MEASURE: Results of VEMP testing. RESULTS: Comparisons between VEMPs and results of the other three examinations revealed no correlations. Complete disappearance of VEMPs was observed only in patients with tumors arising from inferior vestibular nerves. Patients in whom hearing was preserved tended to have preserved VEMPs. Some patients showed damaged hearing and normal VEMP results, although with inferior vestibular schwannomas. A patient with a tumor arising from a cochlear nerve exhibited preservation of VEMP, preserved caloric response, and moderate hearing loss. CONCLUSIONS: Inferior vestibular nerve function and hearing level were reflected in VEMP results. Prediction of the nerve of origin of a tumor was possible only in certain restricted cases.     

Variance of vestibular-evoked myogenic potentials

OBJECTIVES/HYPOTHESIS: Vestibular-evoked myogenic potential (VEMP) has been thought to originate from sacculus. The variance of this potential and the effectiveness of the adjustments of pInII amplitudes using average muscle tonus of ipsilateral sternocleidomastoid muscle were evaluated. In addition, clinical application of VEMP was examined in patients with acoustic tumors (ATs) and vestibular neurolabyrinthitis (VNL). STUDY DESIGN: Prospective evaluation of the VEMP in 18 normal volunteers and 6 patients. METHODS: Variance and left-right difference of each parameter, including pI latency, nII latency, pInII amplitude, and threshold, was analyzed. Input-output function of pInII amplitude was evaluated. Average muscle tonus was calculated in 20 ears and applied for adjustment of pInII amplitude. Sensitivity of each parameter of VEMP was examined in 3 patients with ATs and 3 patients with VNL. RESULTS: VEMP was present in all 36 ears of 18 control subjects. Thresholds of VEMP for normal subjects were 80 to 95 dB normal hearing level (nHL). The muscle tonus affected pInII amplitude significantly; however, no statistically significant improvement was observed in test-retest investigation after adjustment using muscle tonus. The threshold of the affected side was elevated compared with the non-affected side in all patients with ATs, whereas 2 of 3 patients showed normal pInII-ratio. One patient with VNL presented normal VEMP, whereas 2 patients presented no VEMP to the highest stimulus intensity. CONCLUSIONS: Interaural difference of thresholds might be the most useful parameters. Adjustment using average muscle tonus is not necessary when the subject is able to get sufficient muscle tonus.     

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.

Effect of click duration on vestibular-evoked myogenic potentials

CONCLUSIONS: The 0.5-VEMP demonstrated a more prominent waveform morphology than either the 0.1- or 0.2-VEMPs. In addition, the 0.5-VEMP had smaller interaural latency differences than the 1.0-VEMP. These findings suggest that 0.5 ms is superior to other click durations in terms of yielding VEMP responses for clinical use. OBJECTIVE: In order to establish the ideal stimulus condition for vestibular-evoked myogenic potentials (VEMPs), we studied the use of various click durations to generate different response patterns in normal subjects. The influence of click durations on VEMPs is described and the optimal stimulation duration for clinical use is suggested. MATERIAL AND METHODS: This was a prospective study. Eighteen healthy volunteers (36 ears) underwent VEMP tests. Four click durations (0.1, 0.2, 0.5 and 1.0 ms) were used in a random order to elicit VEMP responses (0.1-, 0.2-, 0.5- and 1.0-VEMP, respectively). The latency of each peak (p13, n23), the peak-to-peak interval and amplitude (p 13-n23) and the relative amplitude (defined as the amplitude divided by that of the 0.5-VEMP) were measured and compared. RESULTS: Click stimulation of 34 ears (94%) produced 0.1-VEMP responses, whereas positive 0.2-, 0.5- and 1.0-VEMP responses were observed in 36 (100%). The latencies of peaks p13 and n23 were significantly prolonged between successive stimulus durations from 0.1 to 1.0 ms (p <0.05), in contrast to the p13-n23 intervals (p >0.05). The 1.0-VEMP displayed the largest SDs of latencies and interval among the four different VEMPs. The relative amplitude was significantly increased between successive durations from 0.1 to 0.5 ms (alphaT <0.05), but there was no significant difference between 0.5 and 1.0 ms (alphaT >0.05).     

Perioperative recordings of vestibular-evoked myogenic potentials in otosclerosis.

OBJECTIVES: The aim of the present study was to investigate saccular function in patients with otosclerosis. Furthermore, the influence of stapedotomy on the vestibular-evoked myogenic potentials (VEMPs) should be demonstrated. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. METHODS: Bone-conducted tone-burst-evoked VEMPs were measured in 23 patients (25 ears) with unilateral or bilateral otosclerosis preoperatively and postoperatively. RESULTS: Preoperatively, VEMPs could be recorded in 11 ears (44%). There was no statistically significant correlation among the extent of preoperative sensorineural hearing loss, age, and VEMP measurements. Postoperatively, VEMPs were found in 14 ears (56%). In three cases (12%), VEMPs reappeared after surgery. The rare cases of preoperative vertigo could not be correlated to the nonappearance of VEMPs. CONCLUSION: Stapedotomy surgery does not influence VEMPs, implying that the saccular receptors are not injured by surgery. Moreover, in some cases, the elicitability of VEMPs was improved by stapedotomy surgery. Seemingly, otosclerosis can influence the generation of VEMPs most probably due to an involvement of the otolith organ's saccular receptors. No correlation was found between the clinical occurrence of vertigo and the elicitability of VEMPs.     

The otolithic organ as a receptor of vestibular hearing revealed by vestibular-evoked myogenic potentials in patients with inner ear anomalies

The human vestibule has preserved an ancestral sound sensitivity and it has been suggested that a reflex could originate from this property underlying cervical muscle micro-contractions secondary to strong acoustic stimulation. Previous studies have established that an early component of loud sound-evoked myogenic potentials from the sternocleidomastoid muscle originate in the vestibule. This is based on findings that the response can still be obtained from patients with complete loss of cochlear and vestibular (semi-circular canal) function. Our data confirm, in a more direct way, a saccular origin of this short-latency acoustic response and verifies that a saccular acoustic response persists in the human ear. The contribution of this response to the perception of loud sounds is discussed. It is concluded that vestibular response to sound might be used to assist in the rehabilitation of deafness.     

Clinical studies of vestibular myogenic potentials

This paper is focused on the patterns of evoked vestibular myogenic potentials associated with the involvement of different segments of the the sacculo-neck reflex arc. Specifically, lesions of the vestibular analyzer at the receptor level, changes in the transmission system and at the muscular level are considered. Various patterns of evoked vestibular myogenic potentials characteristic of the disturbance of a given segments of the sacculo-neck reflex arc are described.     

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.     

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.     

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.     

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.     

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.     

Vestibular-evoked myogenic potentials in three patients with large vestibular aqueduct

An enlarged vestibular aqueduct (LVA) is a common congenital inner ear anomaly responsible for some unusual vestibular and audiological symptoms. Most of the cases show bilateral early onset and progressive hearing loss in children. The gross appearance on CT scan of the inner ear is generally normal. However, precise measurements of the inner ear components reveal abnormal dimensions, which may account for the accompanying auditory and vestibular dysfunction. Despite extensive studies on hearing and the vestibular apparatus, saccular function is not studied. To our knowledge this is the first report of saccular malfunction in three patients with LVA by means of vestibular evoked myogenic potentials. Conventional audiograms revealed bilateral severe sensorineural hearing loss in two patients and mixed type hearing loss in one patient. Two of the patients complained about vertigo and dizziness but vestibular assessments of the patients showed normal results. The diagnosis had been made by high-resolution CT scans and MR images of the skull that showed LVA in the absence of other anomalies. The VEMP threshold measured from the ear with LVA in two patients with unilateral enlargement of the vestibular aqueduct was 75–80 dB nHL whereas the threshold from normal ears was 95 dB nHL. The third patient with mixed type hearing loss and bilateral LVA had VEMP responses despite a big air–bone gap in the low frequency range. The VEMP in this patient was greater in amplitude and lower in threshold in the operated ear (the patient had a tympanoplasty which did not improve her hearing). These findings and results of other patients with Tullio phenomenon and superior semicircular canal dehiscence, who also showed lower VEMP threshold, confirmed the theory of a ‘third window’ that allows volume and pressure displacements, and thus larger deflection of the vestibular sensors, which would cause the vestibular organ to be more responsive to sound and pressure changes.     

Preoperative versus postoperative role of vestibular-evoked myogenic potentials in cerebellopontine angle tumor

OBJECTIVE/HYPOTHESIS: Vestibular-evoked myogenic potential (VEMP) examination was performed on patients with a cerebellopontine angle (CPA) tumor to evaluate its clinical role. METHODS: Patients with a CPA tumor were subjected to caloric test and VEMP examination. Follow-up study was performed 1 year after the surgery. RESULTS: Six (69%) of the 9 tumors did not exhibit either caloric response or VEMP on the lesioned side. Three patients received tumor excision and all tumors involved both the superior and inferior vestibular nerves. Two (22%) of the 9 tumors had normal caloric responses but no VEMP. One underwent surgical excision, and the tumor originated from the inferior vestibular nerve. In the follow-up study, only 1 patient with epidermoid cyst presented complete recovery of caloric response and VEMP, whereas in the other 3 patients with vestibular schwannoma, the responses were all absent persistently. CONCLUSION: Before surgery, VEMP test can be used to predict the nerve of origin and to formulate the best surgical approach. After surgery, VEMP test can be used to define the nature of the tumor (compressing or infiltrating the nerve) and disclose the residual function of the inferior vestibular nerve.     

梅尼埃病眼肌前庭诱发肌源性电位的临床研究

目的通过对梅尼埃病(Meniere disease,MD)患者眼肌前庭诱发肌源性电位(ocular vestibular-evoked myogen-ic potential,o VEMP)结果进行分析,进一步探讨梅尼埃病患者o VEMP的临床特征。方法对66例梅尼埃病患者及27例年龄、性别与之匹配的健康人进行o VEMP测试,分析对比oVEMP的引出率及各参数指标。结果 oVEMP在病例组患侧的引出率为41.7%、健侧为55%,对照组为100%;患侧与健侧比较差异无统计学意义(P>0.05),患侧、健侧与对照组比较差异均有统计学意义(P<0.05)。病例组患侧、健侧及对照组间o VEMP的振幅及不对称比均有统计学差异(P<0.05),然各波潜伏期相比无统计学意义。整体来讲,梅尼埃病患者oVEMP引出率随听力学分期升高而呈逐渐下降趋势。结论梅尼埃病患者无论健侧还是患侧,其oVEMP异常均较显著,且以患侧变化显著,提示MD患者的椭圆囊功能受损,oVEMP可用于评估MD患者椭圆囊功能,且进一步对其诊疗作出指导。     

Postoperative imaging and follow-up of vestibular schwannomas.

OBJECTIVE: No standards exist regarding patient follow-up after complete vestibular schwannoma resection. We surveyed neurotologists and neurosurgeons to determine practice patterns. STUDY DESIGN: A nonrandomized sample of American Neurotology Society and North American Skull Base Society members was surveyed. Questions concerned years in practice, experience with vestibular schwannoma surgery, and postoperative follow-up algorithms given the scenario of complete gross tumor removal. Data were collected, tallied, and statistically analyzed. SETTING: Academic and private practice neurotologists and neurosurgeons. SUBJECTS: Nonrandom sample of American Neurotology Society and North American Skull Base Society members. MAIN OUTCOME MEASURES: Number of postoperative magnetic resonance imaging scans, timing of magnetic resonance imaging scans, timing of final magnetic resonance imaging scan, timing of final visit, and variability between specialties. RESULTS: Four hundred ninety-eight surveys were sent and 135 were returned (27.1%). The average number of postoperative magnetic resonance imaging scans was 3.6 for neurotologists (range, 1-11) and 5.6 for neurosurgeons (range, 1-13). This was statistically significant (p >0.001). There was no correlation between number of magnetic resonance imaging scans and either years in practice or tumor experience. Average length of follow-up varied greatly (1 year to lifetime) but was most commonly 5 years. Eight percent of neurotologists varied their postoperative routine on the basis of surgical approach, whereas none of the neurosurgeons did. CONCLUSION: There remains no standard postoperative imaging algorithm for patients after complete vestibular schwannoma resection.     

Ocular vestibular evoked myogenic potentials in patients with acoustic neuroma

To assess the usefulness of vestibular testing in patients with acoustic neuroma, considering two main aspects: to compare diagnostic sensitivity of the current vestibular tests, especially considering ocular vestibular evoked myogenic potentials (OVEMPs) and to identify pre-operative localization of the tumor (inferior vestibular nerve vs. superior vestibular nerve) only with the help of vestibular electrophysiological data. Twenty-six patients with unilateral acoustic neuroma (mainly intracanalicular type) were studied with a full audio-vestibular test battery (pure tone and speech audiometry, caloric bithermal test, vibration-induced nystagmus test (VIN), cervical and OVEMPs). 18 patients (69 %) showed abnormal caloric responses. 12 patients (46.2 %) showed a pattern of VIN test suggestive of vestibular asymmetry. 16 patients (61.5 %) showed abnormal OVEMPs (12 only to AC, 4 both to AC and BC). 10 patients (38.5 %) showed abnormal cervical vestibular evoked myogenic potentials (5 both to AC and BC, 5 only to AC). In one case, results of vestibular evoked potentials and caloric test were confirmed by intra-operative and post-operative findings. Results of electrophysiological tests in AN patients could be helpful for planning the proper surgical approach, considering that sensitivity of every exam is quite low in intracanalicular lesion; clinical data allow a better interpretation of vestibular evoked myogenic potentials.     

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。