Vestibular Evoked Myogenic Potentials Amplitudes Research Articles

Correlation of Superior Canal Dehiscence Surface Area With Vestibular Evoked Myogenic Potentials, Audiometric Thresholds, and Dizziness Handicap.

To correlate objective measures of vestibular and audiometric function as well as subjective measures of dizziness handicap with the surface area of the superior canal dehiscence (SCD). Retrospective chart review and radiological analysis. Single tertiary academic referral center. Preoperative computed tomography imaging, patient survey, audiometric thresholds, and vestibular evoked myogenic potential (VEMP) testing in patients with confirmed SCD. Image analysis techniques were developed to measure the surface area of each SCD in computed tomography imaging. Preoperative ocular and cervical VEMPs, air and bone conduction thresholds, air-bone gap, dizziness handicap inventory scores, and surface area of the SCD. Fifty-three patients (mean age 52.7 yr) with 84 SCD were analyzed. The median surface area of dehiscence was 1.44 mm (0.068-8.23 mm). Ocular VEMP amplitudes (r = 0.61, p <0.0001), cervical VEMP amplitudes (r = 0.62, p <0.0001), air conduction thresholds at 250 Hz (r = 0.25, p = 0.043), and air-bone gap at 500 Hz (r = 0.27, p = 0.01) positively correlated with increasing size of dehiscence. An inverse relationship between cervical VEMP thresholds (r = -0.56, p < 0.0001) and surface area of the dehiscence was observed. No association between dizziness handicap and surface area was identified. Among patients with confirmed SCD, ocular and cervical VEMP amplitudes, cervical VEMP thresholds, and air conduction thresholds at 250 Hz are significantly correlated with the surface area of the dehiscence.

EP 140. Vestibular evoked myogenic potentials: A retrospective analysis

Diagnostic testing of the vestibular system is an integral part of assessment of patients with balance dysfunction. Rediscovery of Vestibular Evoked Myogenic Potentials (VEMP) has introduced a new dimension to vestibular assessment, especially otolith function. We present a retrospective analysis of both C-VEMP and O-VEMP in neurologic & otologic conditions. Data collated retrospectively from records of 98 patients referred for diagnostic VEMP testing to the Electrophysiology laboratory. Presenting symptoms were imbalance and giddiness. 45 male and 53 female patients in the age range of 17–79 years. 38 had Benign Paroxysmal Positional Vertigo (BPPV), 12 Acute Vestibular Neuronitis, 11 Meniere’s Disease, 7 Chronic Otitis Media ( 3 right, 2 left and 2 bilateral ). 1 was referred to confirm left Superior Canalicular Dehiscence, 9 Parkinson Disease, 1 ProgressiveSupranuclearPalsy and 4 Multiple Sclerosis. 15 remained unclassifiable and were categorised as Vertigo Not Otherwise Specified (NOS). Cervical and Ocular VEMP were performed on both ears on all the patients with Medicaid EP machine. Testing done in one session lasting about 30 minutes for each patient. Rest periods given between sets to prevent muscle fatigue. Cervical VEMP: active recording electrodes on Sternocleidomastoid belly ipsilateral to auditory stimuli. Reference on the manubrium sterni. Patients instructed to raise the head about 30 degrees above the bed and hold it actively at that level . Ocular VEMP: recording electrodes were placed contralaterally, active 1 cm inferior to lower eyelid and reference, 2 cm below that. Maximum upgaze was encouraged during testing. Ground electrode: forehead for both tests. Stimulation Parameters: Rarefaction clicks: 100 microsec duration, 5 Hz frequency , intensity 120–125 dB nHL, headphones. Recording Parameters: Filters: Low frequency filter- 20 Hz, High frequency filter- 3 KHz. Sweep: 10 msec/divn. Total sweep of 100 msec. Gain: 100 microvolts /divn. Notch: None. Averages: 100/set, 2 sets for each test. Parameters analysed : Latencies of P13, N23 and amplitude of cervical VEMP on both sides. Latencies of N10, P16 and amplitude of ocular VEMP on both sides. Comparison against normative values and two tailed t test with unequal variance were performed to look for statistically significant deviation in each subgroup of diseases. There was no statistically significant difference in latencies and amplitudes of cervical (p = 0.39 and 0.28 for left and right respectively ) and ocular VEMP (p = 0.4 and 0.64 for left and right respectively) in BPPV. In some patients with Acute Vestibular Neuronitis cervical and ocular responses were absent. Very significant difference in latencies and amplitudes (p < 0.01 on left, p < 0.001 bilaterally) were noted. In Meniere’s disease, p values < 0.01 were obtained uniformly for both cervical and ocular VEMP. p < 0.001 for cervical and ocular VEMP in Otitis Media except the left ocular VEMP which trended the disease. PD and PSP group showed statistically significant differences in cervical and ocular VEMP latencies and amplitudes (p < 0.01). Number of patients with Multiple Sclerosis is small and the results are inconclusive. In the sole patient with left Superior canal dehiscence, the cervical and ocular VEMP were larger than normal ( more than twice in amplitude as against average for the age) on the left thus underscoring its use in this condition. 15 patients had imbalance and giddiness, but not diagnosed with a CNS, PNS or vestibular disorder. Interestingly the Cervical VEMP was significantly abnormal (p < 0.001) but the Ocular VEMP did not show statistically significant deviation in latency or amplitude. This suggests a dichotomy between saccular & utricular pathology, the former being responsible for the patients symptoms. This is, to the best of our knowledge the first report of abnormalities of both Cervical and Ocular VEMP in patients with neurologic and neurootologic disorders from India. The role of VEMPs in studying degenerative neurological disorders (PD and PSP) with imbalance and falls has been explored and since abnormalities in both cervical and ocular VEMPs are noted,suggesting a role for the vestibular system and central connections in imbalance & loss of posture in these conditions. Role of VEMP in MS is routinely mentioned, but it is at best an adjunct diagnostic procedure. The lack of usefulness of VEMP in BPPV has been underscored by this study. But it may be useful in acute attacks of Meniere’s disease and Acute Vestibular Neuronitis to guage the extent and laterality of damage, especially since these disorders are bilateral.Our findings suggest that Ocular VEMP is more sensitive than Cervical VEMP in Vestibular Neuronitis. In chronic otitis media VEMPs are abnormal and can be useful to evaluate integrity of labyrinthine function. The main drawback is the paucity of numbers in different categories. Based on these findings we propose to enrol more patients, especially in the neurological subsets prospectively to elucidate the role of VEMP.

Utilisation of multi-frequency VEMPs improves diagnostic accuracy for Meniere's disease.

To determine whether vestibular evoked myogenic potential (VEMP) measurements that combine the VEMP 500/1000Hz frequency tuning ratio and the inter-aural asymmetry ratio can reliably detect unilateral Meniere's disease ears as compared to healthy controls. Forty-two consecutive patients with certain unilateral Meniere's disease (as confirmed using a locally enhanced inner ear MRI (LEIM)) were assessed. Cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular evoked myogenic potentials (oVEMP) were recorded at 500 and 1000Hz. The VEMP amplitudes, asymmetry ratios, and the 500/1000Hz amplitude ratios were compared with those of 21 age-matched healthy controls. A multi-frequency VEMPs score that combined: (1) the cVEMP 500/1000Hz amplitude ratio, (2) the oVEMP 500/1000Hz amplitude ratio, (3) the 500Hz cVEMP asymmetry ratio, (4) the 1000Hz cVEMP asymmetry ratio, produced a ROC curve with an area under the curve (AUC) of 0.814. The inclusion of audiology data further improved the result to 0.906. This score can be used to discriminate with a good degree of clinical accuracy between Meniere's ears (unilateral) and those of healthy controls. Multi-frequency VEMP analysis offers a simple, cost-effective solution to the diagnostic difficulties presented by Meniere's disease.

Properties of 500Hz air- and bone-conducted vestibular evoked myogenic potentials (VEMPs) in superior canal dehiscence.

To compare threshold and amplitude properties for air- (AC) and mastoid bone-conducted (BC) cervical (cVEMP) and ocular (oVEMP) vestibular evoked myogenic potentials in superior canal dehiscence (SCD). Thirteen patients (53±14yrs) clinically diagnosed with SCD were tested using AC 500Hz sound and BC 500Hz transmastoid vibration. Baseline intensities of 135dBpSPL and 138dBpFL respectively were used and reduced until the response amplitudes were less than 2.5 standard deviations of the prestimulus baseline mean. SCD VEMP amplitudes, response gradients and threshold parameters for the initial peaks for the cVEMP (ipsilateral) and the oVEMP (contralateral) were compared with results for normal subjects over a range of intensities. Despite higher amplitudes, reflex gradients against intensity for AC and BC cVEMPs were significantly less in SCD than normals (P≪0.001) while AC and BC oVEMP gradients were not significantly different between the groups. Abnormally low thresholds for AC 500Hz were present for 85% of cVEMPs and 62% of oVEMPs. Abnormally low BC 500Hz thresholds were seen for 33% of cVEMPs and 83% of oVEMPs. Amplitudes for AC 500Hz were compared over the 135-105dBpSPL intensity range. The cVEMP showed more pathologically large amplitude responses with the lower stimulus intensities (135dBpSPL: 5%, 105dBpSPL: 100%) whereas the oVEMP demonstrated high rates of amplitude increases for all intensities (129-111dBpSPL: 92%). The pattern of pathologically large amplitudes evoked by BC 500Hz was similar for both reflexes such that both cVEMPs and oVEMPs showed maximum prevalence of abnormally large responses around 117dBpFL (cVEMP: 58%, oVEMP: 83%). In SCD, both AC and BC evoked cVEMPs show evidence of saturation but this is not evident for oVEMPs. Both cVEMPs and oVEMPs show frequent abnormalities of amplitudes and thresholds in SCD compared to normal subjects but the sensitivities differed between measures. Previous evidence of saturation of cVEMP responses in SCD was confirmed. For diagnosis, AC cVEMP amplitudes at 105dBpSPL or AC-evoked oVEMP amplitudes both have over 90% sensitivity in separating SCD from normal responses.

Vestibulo-spinal and vestibulo-ocular reflexes are modulated when standing with increased postural threat

We investigated how vestibulo-spinal reflexes (VSRs) and vestibulo-ocular reflexes (VORs) measured through vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) outcomes, respectively, are modulated during standing under conditions of increased postural threat. Twenty-five healthy young adults stood quietly at low (0.8 m from the ground) and high (3.2 m) surface height conditions in two experiments. For the first experiment (n = 25) VEMPs were recorded with surface EMG from inferior oblique (IO), sternocleidomastoid (SCM), trapezius (TRP), and soleus (SOL) muscles in response to 256 air-conducted short tone bursts (125 dB SPL, 500 Hz, 4 ms) delivered via headphones. A subset of subjects (n = 19) also received horizontal and vertical head thrusts (∼150°/s) at each height in a separate session, comparing eye and head velocities by using a vHIT system for calculating the functional VOR gains. VEMP amplitudes (IO, TRP, SOL) and horizontal and vertical vHIT gains all increased with high surface height conditions (P < 0.05). Changes in IO and SCM VEMP amplitudes as well as horizontal vHIT gains were correlated with changes in electrodermal activity (ρ = 0.44-0.59, P < 0.05). VEMP amplitude for the IO also positively correlated with fear (ρ = 0.43, P = 0.03). Threat-induced anxiety, fear, and arousal have significant effects on VSR and VOR gains that can be observed in both physiological and functional outcome measures. These findings provide support for a potential central modulation of the vestibular nucleus complex through excitatory inputs from neural centers involved in processing fear, anxiety, arousal, and vigilance.

Evaluating Inhibition of Motoneuron Firing From Electromyogram Data to Assess Vestibular Output Using Vestibular Evoked Myogenic Potentials.

Vestibular evoked myogenic potentials (VEMPs) are due to vestibular responses producing brief inhibitions of muscle contractions that are detectable in electromyographic (EMG) responses. VEMP amplitudes are traditionally measured by the peak to peak amplitude of the averaged EMG response (VEMPpp) or by a normalized VEMPpp (nVEMPpp). However, a brief EMG inhibition does not satisfy the statistical assumptions for the average to be the optimal processing strategy. Here, it is postulated that the inhibition depth of motoneuron firing is the desired metric for showing the influence of the vestibular system on the muscle system. The authors present a metric called "VEMPid" that estimates this inhibition depth from the EMG data obtained in a usual VEMP data acquisition. The goal of this article was to compare how well VEMPid, VEMPpp, and nVEMPpp track inhibition depth. To find a robust method to compare VEMPid, VEMPpp, and nVEMPpp, realistic physiological models for the inhibition of VEMP EMG signals were made using VEMP data from four measurement sessions on each of the five normal subjects. Each of the resulting 20 EMG-production models was adjusted to match the EMG autocorrelation of an individual subject and session. Simulated VEMP traces produced by these models were used to compare how well VEMPid, VEMPpp, and nVEMPpp tracked model inhibition depth. Applied to simulated and real VEMP data, VEMPid showed good test-retest consistency and greater sensitivity at low stimulus levels than VEMPpp or nVEMPpp. For large-amplitude responses, nVEMPpp and VEMPid were equivalent in their consistency across subjects and sessions, but for low-amplitude responses, VEMPid was superior. Unnormalized VEMPpp was always worse than nVEMPpp or VEMPid. VEMPid provides a more reliable measurement of vestibular function at low sound levels than the traditional nVEMPpp, without requiring a change in how VEMP tests are performed. The calculation method for VEMPid should be applicable whenever an ongoing muscle contraction is briefly inhibited by an external stimulus.

Increased gain of vestibulospinal potentials evoked in neck and leg muscles when standing under height-induced postural threat

ObjectiveTo measure changes in amplitudes of vestibular evoked myogenic potentials (VEMPs) elicited from neck, upper and lower limb muscles during a quiet standing task with increased postural threat achieved by manipulating surface height. Methods: Twenty eight subjects were tested while standing on a platform raised to 0.8m and 3.2m from the ground. Surface electromyography was recorded from the ipsilateral sternocleidomastoid (SCM), biceps brachii (BB), flexor carpi radialis (FCR), soleus (SOL) and medial gastrocnemius (MG) muscles. Stimulation was with air-conducted short tone bursts (4ms). After controlling for background muscle activity, VEMP amplitudes were compared between heights and correlated with changes in state anxiety, fear and arousal. Results: VEMP amplitude significantly increased in SCM (9%) and SOL (12.7%) with increased surface height (p<0.05). These modest increases in SCM VEMP amplitude were significantly correlated with anxiety (Rho=0.57, p=0.004) and confidence (Rho=−0.38, p=0.047) and those for SOL were significantly correlated with anxiety (Rho=0.33, p=0.049) and fear (Rho=0.36, p=0.037). Conclusion: Postural threat significantly increased vestibulospinal reflex (VSR) gains. Results demonstrate that VEMPs can be used to test different VSR pathways simultaneously during stance. Since fear and anxiety are prevalent with vestibular disorders, they should be considered as potential contributing factors for clinical vestibular outcome measures.

Association between saccular function and gait speed: data from the Baltimore Longitudinal Study of Aging.

To investigate whether otolith function (saccular and utricular) is associated with walking performance. Cross-sectional analysis of observational data collected in the Baltimore Longitudinal Study of Aging. National Institute on Aging Intramural Research Program Clinical Research Unit at Harbor Hospital, Baltimore, Maryland. Community-dwelling participants. Cervical and ocular vestibular evoked myogenic potentials (VEMPs) were used to assess saccular and utricular function, respectively. Cervical and ocular VEMP latency and amplitude responses and usual, rapid, and narrow (20 cm) gait speed assessed over a 6-m course. In 314 participants (mean age, 73.1 yr; range, 26-96 yr), cervical VEMP amplitude mediated the association between age and gait speed-particularly narrow walk speed-in both men and women. Cervical VEMP latency had an independent association with gait speed in age-, height-, and weight-adjusted analyses, although the direction of the association differed by sex. Greater cervical VEMP latency was associated with slower usual, rapid, and narrow gait speed in women but faster rapid gait speed in men. Neither the amplitude nor latency of ocular VEMP was associated with gait speed in men or women. These findings suggest that age-related slowing of gait speed is in part mediated by the decreased magnitude of saccular response associated with age. The sex-related differential association between saccular response latency and gait speed requires further study.

On the impact of examiners on latencies and amplitudes in cervical and ocular vestibular-evoked myogenic potentials evaluated over a large sample (N = 1,038).

Vestibular-evoked myogenic potentials (VEMPs) are frequently used in the clinical diagnosis and research of vertigo syndromes. Altered latencies or amplitudes are typically interpreted as an indication of disturbance in the processing of vestibular stimuli along the otolithic pathways. Correct interpretation, however, can be difficult as VEMP amplitudes can vary greatly across subjects and across laboratories, likely because they are very sensitive to measurement conditions. Here, we attempted to quantify the impact of examiner differences on VEMP data. We collected data from 1,038 people using eight different experimental examiners, and investigated the effect of examiner on VEMP latencies and amplitudes. We found that the examiner collecting the data had a strong effect on outcome measures with significant differences (p < 0.001) in cVEMP and oVEMP latencies and in oVEMP amplitudes. No significant differences between examiners were found for the cVEMP amplitudes. When we compared the healthy and pathological sides of patients with a clinically diagnosed unilateral disease, no significant differences between sides were found. Given our results and the results reported in the literature, we conclude that the signal features of VEMPs are very sensitive to variables that may be influenced by the examiner. The field should therefore work on a better standard for VEMP recordings.

Epidemiology of vestibular evoked myogenic potentials: Data from the Baltimore Longitudinal Study of Aging

ObjectiveTo evaluate whether age-related changes in vestibular evoked myogenic potentials (VEMPs) differ by demographic and cardiovascular risk groups. MethodsParticipants in the Baltimore Longitudinal Study of Aging underwent cervical and ocular VEMP testing. VEMP latency, amplitude, asymmetry ratios, and prevalence of absent responses were compared across demographic and cardiovascular risk groups. ResultsIn 257 participants (mean age 72.9, 57% female), ocular VEMP (oVEMP) n10 latency increased by 0.12ms/decade while amplitude decreased by 2.9μV/decade. Black participants had better oVEMP function (shorter latency, increased amplitude, and decreased odds of absent responses) relative to white participants. In 250 participants (mean age 72.6, 54% female), EMG-corrected cervical VEMP (cVEMP) amplitude decreased by 0.14μV/decade and p13 latency was 0.38ms longer in males. The odds of absent responses were significantly higher in individuals age ⩾80 for oVEMPs, and age ⩾70 for cVEMPs. Cardiovascular risk factors had no association with VEMP parameters. ConclusionsWe confirmed age-related declines in otolith function, and observed a protective effect of black race on oVEMP latency and amplitude. SignificanceThese results illustrate how measures of otolith function change with age in community-dwelling adults. Further investigations are needed to ascertain whether better otolith function in blacks might contribute to a lower risk of mobility disability and falls.

The Clinical Utility of Vestibular Evoked Myogenic Potentials in Patients of Benign Paroxysmal Positional Vertigo.

Vestibular Evoked Myogenic Potentials (VEMP) is an emerging tool to diagnose Benign Paroxysmal Positional Vertigo (BPPV). The clinical utility of VEMP has been reported only in small accord in Indian literature. To study the latency and amplitude of VEMP in patients with BPPV and compare it with that of normal subjects. The study included two groups. Group one (control group) were 18 normal subjects. Group two (test group) were 15 subjects with unilateral BPPV. Those subjects who fulfilled the selection criteria based on case history and audiological assessment were taken for the VEMP recording. The VEMP response consist of positive and negative successive waves (pI-nI), with latency values in adults about 13 and 23 milliseconds respectively. Data was analysed using Statistical Package for Social Sciences (SPSS) version 12 (Chicago, IL, USA). Unpaired t-test was employed to measure the statistical difference between control group and test group. The difference in n23 and the peak to peak amplitude between the ipsilateral and contralateral ears of the test group were statistically significant, whereas such a difference in the p13 latency turned out to be statistically insignificant. It should be noted that, out of 15 patients in the test group, five patients showed only artifact tracer recordings in both the ears which is considered as no response. The heterogeneity of the results extended from absence of VEMP to prolongation of both p13, n23; prolongation of p13 alone; and even side to side variations. Absent response from the ipsilateral ear, prolonged latency of n23 and decreased peak to peak amplitude (p13, n23), indicates the disease pathology. However, large sample size is required to draw further conclusions and to consolidate the usage of VEMP in the diagnosis of BPPV.

Air Conducted Cervical and Ocular Vestibular Evoked Myogenic Potentials in Peudotumor Cerebri Patients

Objective : Pseudotumor cerebri is a disorder of unknown etiology that results in raised intracranial pressure (ICP) and characterized by attendant signs and symptoms of increased ICP in an alert and oriented patient but without localizing neurologic findings. Vestibular evoked myogenic potentials (VEMPs) are short latency reflex responses produced by stimulation of the vestibular apparatus. The purpose of this study was to determine whether group of pseudotumor cerebri patients have abnormal changes in VEMPs (cervical and ocular) and to analyze the results and compare them with matched group of normal subjects. Design : Ocular and cervical VEMPs were performed to the entire study groups. The responses were obtained from thirteen pseudotumor cerebri patients and compared to fifteen age matched normal subjects. All participants were subjected to audiological assessments that include pure tone audiometry, tympanometry and acoustic reflexes. Results : Ocular and cervical VEMPs amplitudes were reduced in response in pseudotumor cerebri patients than normal but still of non-statistical significant difference p>0.05. Discussion and Conclusion : The results of this study suggest that patients with pseudotumor cerebri do not have statistically significant changes in comparison with the normal control as regard ocular and cervical VEMPs testing. Hence, asserting a query whether there is affection of VEMPs in pseudotumor cerebri patients.

Audiovestibular manifestations in a radiologically confirmed enlarged vestibular aqueduct in congenital nonsyndromic sensorineural hearing loss in Egypt

EnAbstract Background Enlarged vestibular aqueduct (EVA), the most common radiological finding in children with sensorineural hearing loss, is associated with variable auditory and vestibular symptoms. Aim of the work The aim of this study was to determine vestibular findings in patients with EVA. Patients and methods Twenty patients diagnosed with sensorineural hearing loss and EVA were included in the study group and 20 healthy individuals matched for age and sex were included in the control group. Both groups were subjected to the following: complete history taking, general and neurological examination, full ENT examination, pure tone audiometry, tymanometry, high-resolution computed tomography, vestibular evoked myogenic potentials (VEMP), caloric test, and computerized dynamic posturography. Results EVA was bilateral in 14 patients and unilateral in six patients. The VEMP amplitude of wave p13–n23 was higher in ears with EVA and it correlated positively with its size. p13–n23 latencies did not differ significantly from the control group. The caloric test showed an absent response in four patients, unilateral weakness in six patients, and normal results in 10 patients. There was no statistically significant difference in the results of computerized dynamic posturography. Conclusion The results showed a larger VEMP amplitude, which is indicative of a third window lesion. Some patients showed abnormalities in the caloric test, which indicates a peripheral vestibular lesion. VEMP, caloric test, and computerized dynamic posturography testing were effective in the evaluation of patients with EVA.

Otolith Dysfunction as a Possible Cause for the Development of Idiopathic Scoliosis

To investigate whether otolith system, as a major contributor to muscles for postural control, might play a role in the pathogenesis of idiopathic scoliosis (IS). Cervical vestibular-evoked myogenic potentials (VEMP) testing was applied to investigate the otolith function in patients with IS. Twenty-nine healthy patients (mean age 13.5±2.5 y, 4 males) were included. In all but 2 patients, the major curve deviation was to the right and the mean angle deviation was 49.7±21.6 degrees. Nineteen age-matched individuals (10 males) served as controls. The P13 (first positive wave) latencies were comparable in both groups. Patients with IS had significantly longer N23 (first negative wave) latencies than controls. A high correlation between the age and N23 latencies on the right was found in IS patients. A link between the scoliosis angle and VEMP latencies could not be demonstrated.The VEMP amplitudes were higher in patients than in controls, whereas the amplitude asymmetry ratio was similar in both groups. This work brings further evidence for vestibular abnormalities in patients with IS. Prospective studies are needed to elucidate a possible causative relationship between otolith dysfunction and the development of scoliosis. III.

Short tone bursts are better than clicks for cervical vestibular-evoked myogenic potentials in clinical practice

Our aim is to compare short tone burst (STB)--and clicks--stimuli to evoke vestibular-evoked myogenic potentials (VEMPs) in healthy controls. A cross-sectional study in which VEMPs were measured in two sets of 185 and 55 normal volunteers by an air-conducted 500 Hz STBs and clicks, respectively. The test-retest reliability between different sessions was assessed in two subsets of 35 individuals. Moreover, 53 individuals were examined with both stimuli within the same session. Intraclass correlation coefficients (ICC) were used to assess reliability for P1 and N1 latencies, corrected amplitude and asymmetry ratio (AR). The results included that STBs produced a reliable response between different sessions (N = 35; [ICC] = 0.61-0.94, all p < 0.0001). Although clicks produced a reliable response for P1 and N1 latencies and corrected amplitudes (ICC = 0.62-0.74, all p < 0.0001), the amplitude ratio showed a lower reliability [ICC = 0.32 (-0.10 to 0.59)]. The amplitude of VEMP was consistently larger with 500 Hz STBs than clicks for a given sound pressure level. Within the same session, STBs evoked a response in 52/53 subjects (98%) whereas clicks evoked VEMPs only in 44/53 individuals (83%). Conclusions revealed that a 500 Hz STBs elicited consistently larger amplitudes, better reliability across recording sessions and fewer missing responses compared with click-induced VEMPs.

Benign paroxysmal positional vertigo: Is vestibular evoked myogenic potential testing useful?

Conclusions: In benign paroxysmal positional vertigo (BPPV), vestibular evoked myogenic potentials (VEMPs) help to better define the extent of saccular damage and the patient's prognosis. Objectives: To report the results of VEMPs in patients affected by BPPV of the posterior semicircular canal (PSC) in order to evaluate the presence of signs of saccular dysfunction compared to the normal population and to correlate them with the clinical picture. Methods: This was a prospective study in a tertiary referral center; 23 patients affected by BPPV of the PSC and 24 controls were evaluated. All patients underwent complete clinical history and otoneurologic and audiovestibular evaluation consisting of pure-tone audiometry, caloric testing, and registration of VEMPs. Results: VEMP thresholds and latencies were not different between patients and controls. As a group BPPV patients presented significantly higher abnormal VEMPs compared with controls (p < 0.001). Age positively correlated with VEMP threshold in the affected ear of patients and in controls; the number of BPPV attacks positively correlated with threshold and negatively with amplitude of VEMPs in the affected ear; duration of the last attack was negatively correlated with the effect of the maneuver performed.

Ocular and cervical VEMPs: A study of 74 patients suffering from peripheral vestibular disorders

Objective This study compared the results of ocular and cervical vestibular evoked myogenic potentials (VEMPs) tests for healthy subjects with those for patients suffering from vestibular diseases to try to determine the clinical usefulness of combined ocular and cervical STB VEMP testing. Methods Thirty-two healthy volunteers and 74 patients with unilateral vestibular dysfunction underwent tests for ocular and cervical VEMPs induced by AC 100 dB nHL 500 Hz STB combined with caloric and audiometric tests. Results In healthy subjects, the mean P13–N23 peak-to-peak amplitude of cervical VEMPs was much larger than the mean n1–p1 peak-to-peak amplitude of ocular VEMPs. In patients, cervical and ocular VEMPs may be dissociated. The peak-to-peak amplitude of both cervical and ocular tests was abnormally in most of patients suffering from vestibular lesions. No correlations were found between VEMPs, the degree of hearing loss and/or of horizontal canalar paresis. Conclusions Ocular and cervical VEMPs provide complementary information about saccular and utricular otolithic function. Significance Testing of ocular and cervical VEMPs allows the crossed vestibulo-ocular reflex and ipsilateral sacculo-collic reflex to be determined. These tests can help describe vestibular lesions and assess the effects of treatment and should therefore be used clinically.

Technical pitfalls of vestibular-evoked myogenic potentials

In humans, intense sound evokes ipsilateral myogenic potentials in the sternocleidomastoid muscle (SCM) with a short latency positive-negative (p13-n23) waveform. This sound-evoked vestibulocollic reflex is termed the vestibular-evoked myogenic potential (VEMP). In the present study, the technical and diagnostic pitfalls of the VEMP are introduced.An electromyograph (EMG) is used to record signals from a pair of surface electrodes mounted on the upper-half (active electrode) and the sternal head (reference electrode) of the SCM. The positions of the electrodes influence the p13-n23 amplitude and the VEMP waveform. Head rotation around the yaw axis brings the proximal end of the unilateral SCM muscle close to the distal end, making the outline of the SCM muscle more visible on the body surface. This rotation is useful for the precise positioning of the electrodes.The muscle background activity during the test influences the p13-n23 amplitude of the VEMP. Subjects are instructed to rotate their heads around the yaw axis contralateral to the sound stimulation so as to contract their unilateral SCM muscles. During the VEMP test, the background EMG activity of the tested SCM is continuously monitored, and the peak-to-peak amplitude in the interference pattern of the background EMG should be maintained at more than 200 μV. When the attenuation of the amplitude in the interference pattern begins, the subjects should be instructed to rotate their heads once again so as to recover tonic contraction.The muscle background activity during the test is electromyographically estimated based on the integral value of the rectified EMG activity level for 20 milliseconds preceding the stimulus onset. When the integral value of the rectified EMG activity is less than 1000 μV×ms, the background EMG activity of the tested SCM is objectively evaluated as being too low to induce the evoked response.To correct the amplitude according to the muscle background activity, the p13-n23 amplitude is divided by the integral value of the rectified EMG activity level. This correction is important for the test-retest reproductivity of the VEMP amplitude. To diagnose a right-left asymmetry in the VEMP amplitude, the clinical use of the corrected amplitude is recommended.

Age-Related Changes in Vestibular Evoked Myogenic Potentials Using a Modified Blood Pressure Manometer Feedback Method

To collect age-specific vestibular evoked myogenic potential (VEMP) data and to characterize age-related differences in VEMP parameters using a modified blood pressure manometer (BPM) method of sternocleidomastoid (SCM) muscle monitoring. VEMPs were recorded on healthy adults ranging in age from 23 to 84 years with no history of dizziness, neuromuscular pathologies, or cervical complaints. Participants were assigned to 3 groups using a nonprobability static group assignment based on their age. VEMP P1 and N1 latency, threshold, peak-to-peak amplitude, and interamplitude difference (IAD) ratios were obtained at 130 dB SPL. Statistical differences were detected in peak-to-peak mean amplitude and threshold measures among groups. Post hoc analysis revealed that differences shown were between the young group and both older groups. No significant differences were noted in P1 and N1 latencies or IAD ratios. This study confirmed a significant decline in VEMP amplitude and increase in VEMP thresholds in healthy older persons. Normative age-related data may be necessary to properly interpret VEMP recordings in a clinical setting when evaluating aging populations. The BPM method utilized for controlling SCM muscle may be a valuable alternative to control SCM muscle contraction when electromyography equipment is not available.

Asymmetric vestibular evoked myogenic potentials in unilateral Menière patients

Vestibular evoked myogenic potentials (VEMPs) were measured in 22 unilateral Menière patients with monaural and binaural stimulation with 250 and 500 Hz tone bursts. For all measurement situations significantly lower VEMP amplitudes were on average measured at the affected side compared to the unaffected side. Unilateral Menière patients have, in contrast to normal subjects, asymmetric VEMPs, indicating a permanently affected vestibular (most likely otolith) system at the side of hearing loss. The diagnostic value of VEMP amplitude asymmetry measurement in individual patients is low, because of the large overlap of the VEMP amplitude asymmetry range for unilateral Menière patients with that for normal subjects.