Effects of age on the tuning of the cVEMP and oVEMP

Effects of Age on the Frequency Amplitude Ratio of Cervical and Ocular Vestibular Evoked Myogenic Potentials

PURPOSE

An increase in the 1000/500 Hz frequency amplitude ratio (FAR) of the cervical and ocular vestibular evoked myogenic potentials (cVEMP and oVEMP, respectively) may serve as a potential biomarker for diagnosing Meniere's disease (MD). However, the aging process can also result in an increased FAR for VEMPs. In older patients, distinguishing whether changes in VEMP FAR are due to MD or aging processes becomes difficult. We aimed to investigate the effects of age on VEMP FARs and establish a FAR-normative range for different age groups.

METHOD

cVEMP and oVEMP were recorded from a total of 106 participants grouped as young, middle-aged, and older adults using air-conducted tone bursts at 500, 750, and 1000 Hz at 125 dB pSPL. The FAR was calculated for the cVEMP and oVEMP for the following frequencies: FAR1 = 1000/500, FAR2 = 1000/750, and FAR3 = 750/500.

RESULTS

A significant age-related effect was observed on the cVEMP FAR. Although the oVEMP FAR showed an increasing trend with age, it was not statistically significant. Age-based normative FAR values are provided.

CONCLUSIONS

Drawing from the normative FAR from this study, there is evidence that the existing MD diagnostic criteria would misidentify a considerable number of older adults. Therefore, to reduce false positives, we recommend a more stringent cVEMP and oVEMP FAR criterion in older adults.

Test-Retest Reliability of Repetitive Ocular Vestibular Evoked Myogenic Potentials in Myasthenia Gravis Patients and Healthy Control Subjects

PURPOSE

Repetitive ocular vestibular evoked myogenic potentials (ROVEMP) are a novel diagnostic test to quantify neuromuscular transmission deficits in extraocular muscles in myasthenia gravis. We aimed to investigate the test-retest reliability of the ROVEMP and the effect of amplitude and age.

METHODS

We performed the ROVEMP test twice in 19 patients with myasthenia gravis (52.7 ± 19.8 years) and in 15 healthy control subjects (46.5 ± 16 years). The Bland-Altman level of agreement was determined. The relationship between test-retest reliability and signal quality, participant age and signal amplitude was studied.

RESULTS

Limits of agreement were from -179.9 to 139.3 in myasthenia gravis patients and from -56.9 to 89.5 in healthy control subjects. Difference between measurements correlated with signal amplitude ( r = -0.50, P < 0.001). Combining the primary cohort with previously published data from 114 subjects, we found a significant negative correlation between age and reference amplitude ( r = -0.163, P = 0.045).

CONCLUSIONS

This study shows that in our hands, the test-retest reliability of the ROVEMP is not optimal. Measurements with higher reference amplitude had a better quality, higher reproducibility, and increased diagnostic yield. We caution against the use of ROVEMP measurements of lower amplitude in clinical practice. In addition, given the correlation between age and amplitude, age matching of healthy control subjects and patients is essential in future studies.

Multi-frequency VEMPs improve detection of present otolith responses in bilateral vestibulopathy

Objective

To investigate whether multi-frequency Vestibular Evoked Myogenic Potential (VEMP) testing at 500, 750, 1,000, and 2,000 Hz, would improve the detection of present dynamic otolith responses in patients with bilateral vestibulopathy (BV).

Methods

Prospective study in a tertiary referral center. BV patients underwent multi-frequency VEMP testing. Cervical VEMPs and ocular VEMPs were recorded with the Neuro-Audio system (v2010, Neurosoft, Ivanovo, Russia). The stimuli included air-conducted tone bursts of 500, 750, 1,000, and 2,000 Hz, at a stimulation rate of 13 Hz. Outcome measures included the percentage of present and absent VEMP responses, and VEMP thresholds. Outcomes were compared between frequencies and type of VEMPs (cVEMPs, oVEMPs). VEMP outcomes obtained with the 500 Hz stimulus, were also compared to normative values obtained in healthy subjects.

Results

Forty-nine BV patients completed VEMP testing: 47 patients completed cVEMP testing and 48 patients completed oVEMP testing. Six to 15 % more present VEMP responses were obtained with multifrequency testing, compared to only testing at 500 Hz. The 2,000 Hz stimulus elicited significantly fewer present cVEMP responses (right and left ears) and oVEMP responses (right ears) compared to the other frequencies (p ≤ 0.044). Using multi-frequency testing, 78% of BV patients demonstrated at least one present VEMP response in at least one ear. In 46% a present VEMP response was found bilaterally. BV patients demonstrated a significantly higher percentage of absent VEMP responses and significantly higher VEMP thresholds than healthy subjects, when corrected for age (p ≤ 0.002). Based on these results, a pragmatic VEMP testing paradigm is proposed, taking into account multi-frequency VEMP testing.

Conclusion

Multi-frequency VEMP testing improves the detection rate of present otolith responses in BV patients. Therefore, multi-frequency VEMPs should be considered when evaluation of (residual) otolith function is indicated.

Measurement of Ocular Vestibular Evoked Myogenic Potentials: Nasion Reference Montage as an Alternative to the Clinical Standard Montage

OBJECTIVE

To compare two novel electrode montages for ocular, vestibular evoked myogenic potential using single-nasion reference electrodes with the clinical standard montage.

STUDY DESIGN

Randomized crossover experiment.

SETTING

Tertiary referral center.

PARTICIPANTS

Sixty healthy participants.

INTERVENTION

Normal hearing and vestibular function were confirmed with an extensive test-battery. All ocular, vestibular evoked myogenic potential settings were measured with air-conducted tone bursts at 100-dB normal hearing level and a frequency of 500 Hz. Three electrode montages were measured in randomized order: the clinical standard montage ("S"), the nasion reference montage ("N"), and the nasion reference montage with a more lateral active electrode ("L"). Upgaze was standardized to 35 degrees.

MAIN OUTCOME MEASURES

Detection rate, latency of N1 and P1, peak-to-peak amplitude of N1 and P1, signal-to-noise ratio (SNR), asymmetry ratio (AR), concordance of expert assessment, and reliability.

RESULTS

All electrode montages showed detection rates greater than 90%. Latencies for "L" were shorter than for "S" and "N." Amplitudes and SNR for "S" and "N" were higher than for "L," whereas the values for "S" and "N" did not differ significantly. For AR, no significant differences between the montages were assessed. Concordance of experts ranged from 78% for "L" and 89.8% for "N." All montages provided excellent day-to-day reliability (intraclass correlation coefficient ≥0.9) for amplitudes and SNR.

CONCLUSIONS

Montage N could be a useful alternative to the clinical standard montage: although results are roughly equivalent, montage N requires one less electrode to do so.

Vestibular evoked myogenic potential (VEMP) test-retest reliability in adults

BACKGROUND

The technique of measuring ocular vestibular evoked myogenic potentials (oVEMP) in response to Mini-shaker vibration is relatively new, there is a limited normative data to define the presence or absence of a response in the literature.

OBJECTIVE

To determine the test-retest reliability of cervical and ocular VEMPs (cVEMP and oVEMP, respectively) to air-conducted sound (ACS) and bone-conducted vibration (BCV) stimulation and to determine normative ranges for the responses.

METHODS

Twenty normal-hearing individuals (40 ears) and 20 hearing impaired volunteers with normal balance function (40 ears) were examined in this study. ACS cVEMP and BCV oVEMP (using a Mini-shaker) were recorded from both groups to assess the test-retest reliability and to collect normative VEMP data for P1/N1 latencies and amplitudes from 20 normal hearing individuals. To test reliability, VEMP recordings were repeated within the same session.

RESULTS

The test-retest reliability for all the cVEMP parameters showed excellent reliability whereas oVEMP parameters showed between fair and excellent reliability depending on the parameter tested. Normative data for VEMP P1/N1 latencies and amplitudes were established.

CONCLUSIONS

Normative data and test-retest reliability for BCV oVEMP using the Mini-shaker at 100 Hz were established in our study for the first time in the literature. Responses appear reliable.

A Novel COCH p.D544Vfs*3 Variant Associated with DFNA9 Sensorineural Hearing Loss Causes Pathological Multimeric Cochlin Formation

COCH (coagulation factor C homology) is one of the most frequently mutated genes of autosomal dominant non-syndromic hearing loss. Variants in COCH could cause DFNA9, which is characterized by late-onset hearing loss with variable degrees of vestibular dysfunction. In this study, we report a Chinese family with a novel COCH variant (c.1687delA) causing p.D544Vfs*3 in the cochlin. Comprehensive audiometric tests and vestibular function assessments were taken to acquire the phenotypic profile of the subjects. Next-generation sequencing was conducted and segregation analysis was carried out using Sanger sequencing. The proband presented mild vestibular symptoms and normal functional assessment results in almost every test, while the variant co-segregated with hearing impairment in the pedigree. The variant was located beyond the vWFA2 domain, which was predicted to affect the post-translational cleavage of the cochlin via molecular modeling analysis. Notably, in the overexpressing study, by transient transfecting the HEK 293T cells, we found that the p.D544Vfs*3 variant increased the formation of multimeric cochlin. Our result enriched the spectrum of DFNA9-linked pathological COCH variants and suggested that variants, causative of cochlin multimerization, could be related to DFNA9 with sensorineural hearing loss rather than serious vestibular symptoms.

Cervical vestibular evoked myogenic potential (cVEMP) findings in adults with sensorineural hearing loss (SNHL): comparisons between 500 Hz tone burst and narrowband CE-Chirp stimuli

There has been a growing interest in studying the usefulness of chirp stimuli in recording cervical vestibular evoked myogenic potential (cVEMP) waveforms. Nevertheless, the study outcomes are debatable and require verification. In view of this, the aim of the present study was to compare cVEMP results when elicited by 500 Hz tone burst and narrowband (NB) CE-Chirp stimuli in adults with sensorineural hearing loss (SNHL). Fifty adults with bilateral SNHL (aged 20-65 years) underwent the cVEMP testing based on the established protocol. The 500 Hz tone burst and NB CE-Chirp (centred at 500 Hz) stimuli were presented to each ear at an intensity level of 120.5 dB peSPL. P1 latency, N1 latency, and P1-N1 amplitude values were analysed accordingly. The NB CE-Chirp stimulus produced significantly shorter P1 and N1 latencies (p < 0.001) with large effect sizes (d > 0.80). In contrast, both stimuli elicited cVEMP responses with P1-N1 amplitude values that were not statistically different from one another (p = 0.157, d = 0.15). Additionally, age and hearing level were found to be significantly correlated (r = 0.56, p < 0.001), as were age and cVEMP amplitude for each stimulus (p < 0.001). To conclude, since both stimuli were presented at an equivalent intensity level (in dB peSPL), the shorter P1 and N1 latencies of cVEMP produced by the NB CE-Chirp stimulus (centred at 500 Hz) were unlikely due to enhanced saccular stimulation. Another more sensible reason is the temporal adjustment of the chirp stimulus.

Multifrequency Analysis of Masseter Vestibular Evoked Myogenic Potentials in Young Adults

PURPOSE

The purpose of this study was to explore the dynamics of multifrequency tone bursts on the masseter vestibular evoked myogenic potential (mVEMP) parameters. Furthermore, it sought to determine the optimal frequency tuning of mVEMP responses.

METHOD

Twenty young adults with normal hearing sensitivity participated in the study. Bilateral tone burst evoked mVEMPs were obtained using the zygomatic montage at 250-, 500-, 750-, 1000-, 1500-, and 2000-Hz stimulation frequencies. Self-monitoring biofeedback was given during the procedure to confirm the tension of the masseter muscle between 49.9 and 150.6 rms. Furthermore, the electromyography (EMG) scaling was done to avoid any muscle-related irregularities.

RESULTS

Tone burst evoked mVEMPs were found to be 100% present at the stimulation frequencies of 250, 500, 750, and 1000 Hz. There were no ear and gender effects seen for any of the frequencies. Significant shortening of the P1 and N1 latencies with increasing stimulation frequencies was observed. The peak-to-peak amplitude was the highest at 500 Hz and lowest at 2000 Hz tone bursts under both EMG scaled and unscaled conditions.

CONCLUSION

The present revealed higher response rates and larger amplitudes study of mVEMP at lower frequencies, and, therefore, the frequency tuning was seen for the stimulation frequency at 500 Hz.

Peripheral vestibular loss in noise-exposed firefighters

Introduction

Occupational workers are increasingly aware of the risk of noise overexposure to the auditory system but lack awareness about potential risks to the vestibular system. The purpose of this study was to investigate changes in vestibular end organ function in a known at-risk noise-exposed population, firefighters compared to age- and sex-matched controls using electrophysiologic measures of cervical vestibular evoked myogenic potentials (cVEMP).

Methods

A cross-sectional observational study compared cVEMP response characteristics in 38 noise-exposed firefighters. Firefighters were grouped by years of exposure in the fire service. The cVEMP responses were compared within firefighter groups and between firefighters and age- and sex-matched controls. Dependent variables included the response characteristics of amplitude, latency and threshold.

Results

cVEMP response amplitudes were significantly decreased in firefighters compared to their age- and sex-matched controls. Threshold of the cVEMP responses were significantly higher in firefighters compared to controls and firefighters had a higher incidence of absent cVEMP responses compared to controls. Response amplitudes decreased with increasing years in the fire-service at an increased rate compared to their age- and sex-matched controls. Latency of the cVEMP response was not significantly different in firefighters compared to controls. These findings are consistent with both animal and human studies suggesting noise-induced changes in the sacculocollic pathway.

Discussion

In the absence of any reported vestibular symptoms or auditory indicators of noise-induced hearing loss, these early effects on the vestibular system point to a potential hidden vestibular loss.

Utility of Inter-Frequency Amplitude Ratio of Vestibular-Evoked Myogenic Potentials in Identifying Meniere's Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

A recently devised parameter of vestibular-evoked myogenic potential (VEMP) based on the principles of frequency tuning is the inter-frequency amplitude ratio (IFAR). It refers to the ratio of the amplitude of 1000 Hz tone burst evoked VEMP to 500 Hz evoked tone burst. A pathology like Meniere's disease changes the frequency response and alters the frequency tuning of the otolith organs. Because IFAR is based on the principle of frequency tuning of VEMP, it is likely to help identify Meniere's disease. Few studies in the last decade have investigated the utility of IFAR in identifying Meniere's disease. However, a systematic review and a meta-analysis on IFAR in Meniere's disease are lacking. The present study investigates whether the IFAR of VEMP helps identify Meniere's disease and differentiates it from healthy ears and other vestibular pathologies.

DESIGN

The present study is a systematic review and a meta-analysis. The studies investigating the IFAR of cervical and ocular VEMPs in Meniere's disease, healthy controls, and other vestibular pathologies were searched across research databases such as PubMed, Science Direct, and Scopus. The search strategy was developed using the PICO (population, intervention, comparison, and outcomes) format, and Medical Subject Headings (MeSH) terms and Boolean operators were employed. The systematic review was performed using the Rayyan software, whereas the Review Manager software was used to carry out the meta-analysis. A total of 16,605 articles were retrieved from the databases. After the duplicate removal, 2472 articles remained. These were eliminated using title screening, abstract screening, and full-length inspections. A total of nine articles were found eligible for quality assessment and meta-analysis, and the New Castle-Ottawa Scale was used for quality assessment. After the data extraction, 24 six articles were found to have the desired data format for the meta-analysis.

RESULTS

The results showed significantly higher IFAR in the affected ears of individuals in the Meniere's disease group than in the control group's unaffected ears. There was no significant difference between the unaffected ears of individuals in the Meniere's disease group and the ears of the control group. The only study on Meniere's disease and benign paroxysmal positional vertigo found significantly larger ocular VEMP IFAR in ears with Meniere's disease than in benign paroxysmal positional vertigo.

CONCLUSIONS

This systematic review and meta-analysis found IFAR efficient in differentiating Meniere's disease from healthy controls. We also found an enhanced IFAR as a potential marker for Meniere's disease. However, more investigations are needed to confirm the utility of an enhanced IFAR value in the exclusive identification of Meniere's disease.

Effect of Real-Ear Adjusted Stimuli on Vestibular Evoked Myogenic Potential Variability in Children and Young Adults

OBJECTIVES

There is large variability in cervical and ocular vestibular evoked myogenic potential (c- and oVEMP) amplitudes. One potential source of variability is differences in ear canal shape and size. Real ear-to-coupler difference (RECD) values are used to measure the acoustic environment of an individual's ear canal. RECD may be a useful measure to calibrate air conducted VEMP stimuli, which are elicited at high intensities and may put patients at risk of unsafe sound exposure. A recommendation for avoiding unsafe exposure is to use a 125 dB SPL stimulus for individuals with an equivalent ear canal volume (ECV) ≥ 0.9 mL and a 120 dB SPL stimulus for individuals with a smaller ECV. The purpose of this project was to determine if using a stimulus calibrated in the ear using RECD values significantly reduces intra-subject and inter-subject VEMP amplitude variability. We hypothesized that using a RECD-calibrated stimulus would significantly reduce inter-subject amplitude variability but not significantly reduce intra-subject variability. We further hypothesized that an RECD-adjusted VEMP stimulus would better protect against delivering unsafe sound exposure compared to the method of using ECV alone.

DESIGN

Eleven children (4 to 9 years), 10 adolescents (10 to 18 years), and 10 young adults (20 to 40 years) with normal hearing, tympanometry, vestibular and neurological function participated. On all subjects, RECD was measured twice per ear to account for test-retest reliability. cVEMP and oVEMP were then recorded bilaterally with a 500 Hz tone burst at a traditional and an adjusted VEMP intensity level. The traditional intensity level was 125 dB SPL for individuals with ≥ 0.9 mL ECV and 120 dB SPL for individuals with ≤ 0.8 mL ECV. The adjusted intensity level was calculated by subtracting the average 500 Hz RECD measured values from the 500 Hz normative RECD value. This value was applied as a correction factor to a 125 dB SPL stimulus. Peak to peak amplitudes were recorded and used to calculate asymmetry ratios.

RESULTS

Young children had significantly smaller ECVs compared to adolescents and young adults. Young children had larger RECDs; however, this was not significant in post hoc analyses. The method of calibration had no significant effect on intra-subject variability for cVEMP [ F (1, 27)= 0.996, p = 0.327] or oVEMP [ F (1, 25)= 1.679, p = 0.206]. The method of calibration also had no significant effect on inter-subject amplitude variability for cVEMP [ F (1, 120)= 0.721, p = 0.397] or oVEMP [ F (1, 120)= 0.447, p = 0.505]. Both methods of calibration adequately protected against unsafe exposure levels. However, there were subjects with ECVs ≥ 0.9 mL who approached unsafe exposure levels from the ECV-calibrated stimulus, suggesting there may be rare cases in which a 125 dB SPL stimulus is unsafe, even for patients with larger ECVs.

CONCLUSIONS

The calibration method made no significant difference in intra- or inter-subject variability, indicating that the acoustic environment of the outer ear is not significantly contributing to VEMP amplitude variability. The RECD-adjusted stimulus is effective in protecting against unsafe exposure levels for two trials of both c- and oVEMPs. There may be instances where more than two trials of each test are required, which increases the effective stimulation level. Clinicians should be cautious when delivering VEMPs and not unnecessarily expose patients to unsafe levels of sound.

Evaluation of vestibular evoked myogenic potential values in elder patients with hip fractures: A prospective controlled study

Background/Aim: Hip fractures among the elderly are a major public health problem that cause high rates of morbidity and mortality. There are many studies regarding prevention and defining the underlying causes of hip fractures. The purpose of this study was to evaluate the cervical vestibular evoked myogenic potential (cVEMP) test responses of elderly patients without vestibular symptoms hospitalized due to fall-related hip fractures in order to evaluate the subclinical vestibular dysfunction rates in patients with hip fractures. Methods: Twenty-two patients aged 67-79 hospitalized due to fall-related hip fractures and 24 control patients presenting to the orthopedic clinic due to knee pain were included in the study. The participants underwent detailed otological examination and cVEMP tests. The two groups’ cVEMP records were then compared. Results: The demographic characteristics of the participants in the patient and control groups including age, gender, and race were similar. There was no statistically significant difference between the groups’ absent VEMP response rates. No significant difference in terms of P1 and N1 latencies was determined between the right and left ears in either group. The hip fracture group (study group) had significantly increased P1 and N1 latencies in cVEMP which is associated with central vestibular dysfunction. (P=0.008 and P=0.007, respectively). Conclusion: The rate of subclinical peripheral vestibular dysfunction, which can be identified by cVEMP evaluation, is increased in elderly patients with hip fractures caused by low energy trauma. Precautions like vestibular rehabilitation can be a preventive measure for hip fractures in the elderly.

Spatial orientation, postural control and the vestibular system in healthy elderly and Alzheimer's dementia

Background

While extensive research has been advancing our understanding of the spatial and postural decline in healthy elderly (HE) and Alzheimer's disease (AD), much less is known about how the vestibular system contributes to the spatial and postural processing in these two populations. This is especially relevant during turning movements in the dark, such as while walking in our garden or at home at night, where the vestibular signal becomes central. As the prevention of falls and disorientation are of serious concern for the medical service, more vestibular-driven knowledge is necessary to decrease the burden for HE and AD patients with vestibular disabilities.

Overview of the article

The review briefly presents the current "non-vestibular based" knowledge (i.e. knowledge based on research that does not mention the "vestibular system" as a contributor or does not investigate its effects) about spatial navigation and postural control during normal healthy ageing and AD pathology. Then, it concentrates on the critical sense of the vestibular system and explores the current expertise about the aspects of spatial orientation and postural control from a vestibular system point of view. The norm is set by first looking at how healthy elderly change with age with respect to their vestibular-guided navigation and balance, followed by the AD patients and the difficulties they experience in maintaining their balance or during navigation.

Conclusion

Vestibular spatial and vestibular postural deficits present a considerable disadvantage and are felt not only on a physical but also on a psychological level by all those affected. Still, there is a clear need for more (central) vestibular-driven spatial and postural knowledge in healthy and pathological ageing, which can better facilitate our understanding of the aetiology of these dysfunctions. A possible change can start with the more frequent implementation of the "vestibular system examination/rehabilitation/therapy" in the clinic, which can then lead to an improvement of future prognostication and disease outcome for the patients.

Cervical vestibular evoked myogenic potentials in healthy children: Normative values for bone and air conduction

Objectives

To characterize cervical vestibular evoked myogenic potentials (c-VEMPs) in bone conduction (BC) and air conduction (AC) in healthy children, to compare the responses to adults and to provide normative values according to age and sex.

Design

Observational study in a large cohort of healthy children (n = 118) and adults (n = 41). The c-VEMPs were normalized with the individual EMG traces, the amplitude ratios were modeled with the Royston-Wright method.

Results

In children, the amplitude ratios of AC and BC c-VEMP were correlated (r = 0.6, p < 0.001) and their medians were not significantly different (p = 0.05). The amplitude ratio was higher in men than in women for AC (p = 0.04) and BC (p = 0.03). Children had significantly higher amplitude ratios than adults for AC (p = 0.01) and BC (p < 0.001). Normative values for children are shown. Amplitude ratio is age-dependent for AC more than for BC. Confidence limits of interaural amplitude ratio asymmetries were less than 32%. Thresholds were not different between AC and BC (88 ± 5 and 86 ± 6 dB nHL, p = 0.99). Mean latencies for AC and BC were for P-wave 13.0 and 13.2 msec and for N-wave 19.3 and 19.4 msec.

Conclusion

The present study provides age- and sex-specific normative data for c-VEMP for children (6 months to 15 years of age) for AC and BC stimulation. Up to the age of 15 years, c-VEMP responses can be obtained equally well with both stimulation modes. Thus, BC represents a valid alternative for vestibular otolith testing, especially in case of air conduction disorders.

Multifrequency Narrowband Chirp Evoked Cervical Vestibular Myogenic Potentials: Evaluation of Responses in Normal-Hearing Young Adults

Purpose:

The study aimed to explore the various parameters of multifrequency narrowband Claus Elberling chirp (NB CE-chirp) evoked cervical vestibular evoked myogenic potentials (cVEMPs) in normal-hearing healthy young adults. The study also attempted to define the optimal frequency tuning characteristic of NB CE-chirp evoked cVEMPs.

Method:

cVEMP was performed on 26 young healthy adults using four different NB CE-chirps centered at 500, 1000, 2000, and 4000 Hz. The neck torsion method was applied for electrode placement. To have the acute recording, visual feedback of sternocleidomastoid muscle contraction was provided, and electromyography (EMG) scaling was done.

Results:

cVEMPs were present for 100% across all frequencies except at 4000 Hz. Amplitudes between each pair of frequencies were significantly different for EMG scaled and unscaled conditions. Frequency tuning was observed at 500 Hz regardless of scaling done. Positive peak 1 of cVEMP (P1) latencies showed no differences between frequencies while both negative peak 1 of cVEMP and the complex of positive peak 1 and negative peak 1 of cVEMP (P1N1) interpeak latency values decreased with increasing frequency. Interaural amplitude asymmetry ratio showed no difference between scaled and unscaled amplitudes. Intraclass correlation revealed a range of test–retest reliability across frequencies. EMG unscaled amplitude were having relatively lower test–retest reliability consistently across frequencies

Conclusions:

Differences in amplitudes between frequencies with a maximum at 500 Hz can be attributed to the low frequency centered saccular response. No differences in P1 were observed. Yet, N1 latency and P1N1 interpeak latency difference gradually shortened with the decrement in the stimulus duration as the stimulation frequency increased. The lower reliability of EMG unscaled amplitude across frequencies supports the need to use EMG scaling to avoid confounding variables related to muscle contraction.

Changes in vestibular and cochlear function following platinum-based chemotherapy: A preliminary report

OBJECTIVES

This study investigated the changes in vestibular and cochlear function in patients receiving platinum-based chemotherapy.

METHODS

A longitudinal study of 32 participants (10-70 years) receiving chemotherapy participated in the study. Baseline and exit vestibular and hearing assessments that included video head impulse (VHIT) testing, cervical and ocular vestibular evoked myogenic potentials (VEMP), dynamic visual acuity (DVA) and pure-tone audiometry were performed at the patient's treatment venue.

RESULTS

Half (50%) of the participants showed cochleotoxicity from baseline to exit testing, with left ears significantly more affected than right ears. There was no consistent relationship between hearing loss and vestibular dysfunction. DVA yielded normal results at baseline and exit testing in all participants. VEMP responses were absent in 28.1% of participants at baseline, reflecting the challenges of using VEMP for monitoring. VEMP and VHIT results showed a statistically significant (p < 0.05) decline in results from baseline to exit testing; however, participants did not report symptoms related to vestibular dysfunction. VHIT also showed left ears significantly (p < 0.05) more affected than right ears.

CONCLUSION

VHIT proved to be a valuable measure of changes in vestibular function secondary to ototoxicity. Future investigations should determine vestibulotoxicity criteria and optimal protocols for vestibulotoxicity monitoring at the patient's treatment venue.

Effects of aging on ocular vestibular-evoked myogenic potential using ER-3A insert earphone and B81 bone vibrator

Purpose

Aging is a process associated with degeneration and dysfunction of peripheral vestibular system or apparatus. This study aimed to investigate the influence of aging on ocular vestibular-evoked myogenic potential (oVEMP) response rates and recording parameters using the B81 bone vibrator and compare them with air conduction stimuli (ACS) oVEMP response characteristics.

Methods

In 60 healthy participants aged 10–71 years (mean age 39.9; 29 male participants), the oVEMP response was elicited using a B81 bone vibrator and an ER-3A insert earphone. The effects of age and stimulus on oVEMP response rates and recording parameters were evaluated.

Results

Response rates and amplitudes declined with aging using either ACS or bone-conducted vibration (BCV) stimulation, particularly in individuals over 60 years of age, whereas thresholds increased and N1 latencies were prolonged. BCV showed fewer risks of absent oVEMP response than ACS (p = 0.002). BCV acquired higher amplitudes (p &lt; 0.001), lower thresholds, and shorter N1 and P1 latencies (all p &lt; 0.001) than ACS.

Conclusions

The absence of an oVEMP response may be attributed to aging rather than a concurrent vestibular disorder. B81-BCV likely produces higher mechanical drives to the vestibular hair cells at safer and non-traumatic levels compared with ACS and therefore may be more likely to evoke a response in the elderly cohort, whose vestibular function and mechanical sensitivity have declined. Thus, B81-BCV stimulation is more effective and safer to elicit oVEMPs, and it should be recommended when ACS fails in the clinic, particularly in the elderly population.

Inter-trial coherence as a measure of synchrony in cervical vestibular evoked myogenic potentials

BACKGROUND

Cervical vestibular evoked myogenic potentials (cVEMPs) are surface-recorded responses that reflect saccular function. Analysis of cVEMPs has focused, nearly exclusively, on time-domain waveform measurements such as amplitude and latency of response peaks, but synchrony-based measures have not been previously reported.

NEW METHOD

Time-frequency analyses were used to apply an objective response-detection algorithm and to quantify response synchrony. These methods are new to VEMP literature and have been adapted from previous auditory research. Air-conducted cVEMPs were elicited using a 500Hz tone burst in twenty young, healthy participants.

RESULTS

Time-frequency characteristics of cVEMPs and time-frequency boundaries for response energy were established. An inter-trial coherence analysis approach revealed highly synchronous responses with representative inter-trial coherence values of approximately 0.7.

COMPARISON WITH EXISTING METHODS

Inter-trial coherence measures were highly correlated with conventional amplitude measures in this group of young, healthy adults (R² = 0.91 - 0.94), although the frequencies at which these measures had their largest magnitude were unrelated (R² =.02). Conventional measures of peak-to-peak amplitude and latency were consistent with previous literature. Interaural asymmetry ratios were comparable between amplitude- and synchrony-based measures.

CONCLUSIONS

Synchrony-based time-frequency analyses were successfully applied to cVEMP data and this type of analysis may be helpful to differentiate synchrony from amplitude in populations with disrupted neural synchrony.

Effects of Age and Middle Ear on the Frequency Tuning of the cVEMP and oVEMP

BACKGROUND

Upward shift in the air conducted (AC) frequency tuning of vestibular evoked myogenic potentials (VEMPs) as an effect of aging is hypothesized to be due to the microstructural stiffening changes in the inner ear. However, with an AC stimulus, it may be possible that the shift in the frequency tuning of VEMPs as an effect of aging may also be due to contributions from the middle ear.

PURPOSE

The main aim of this study was to examine the effects of age on the frequency tuning of the cervical VEMP (cVEMP) and ocular VEMP (oVEMP) and determine the role of middle ear transmission characteristics in shaping these effects.

RESEARCH DESIGN

Standard group comparison.

STUDY SAMPLE

One-hundred seven participants divided in three groups: young adult, middle-age, and older adults with "normal" middle ear and negative history of neurological or vestibular complaints.

DATA COLLECTION AND ANALYSES

Middle ear measures included static admittance and middle ear resonant frequency. cVEMP and oVEMPs were elicited with AC tone bursts at 500, 750, and 1,000 Hz.

RESULTS

No significant effect of age was observed on any of the middle ear measures. There was a significant effect of age on the amplitude of the cVEMP, but this effect was frequency specific. The age-related reduction in cVEMP corrected amplitude was only observed when the eliciting stimulus was 500 or 750 Hz, with no significant effect observed with a 1,000 Hz stimulus. For the oVEMP, the effects of age were apparent at all stimulus frequencies. We also observed a general upward shift in the frequency tuning of both the cVEMP and oVEMP for middle-age and older adults, with 750 and 1,000 Hz yielding higher response rates and larger amplitudes among middle-aged and older adults. Measurements of middle ear did not significantly contribute to the observed findings.

CONCLUSIONS

The upward shift in frequency tuning of VEMPs among middle age and older adults could be due to the changes in the vestibular system and not from the middle ear. These results support the use of different frequency stimuli (i.e., 750 or 1,000 Hz) to elicit a VEMP if a response is absent using a 500 Hz stimulus, especially in patients over the age of 40.

Exploring Vestibular Assessment in Patients with Headache and Dizziness

Patients often report symptoms of headache and dizziness concomitantly. Symptoms of dizziness can be explored with a comprehensive vestibular assessment, allowing for the investigation of central and peripheral vestibular system contributions to symptoms of dizziness. Patients who report both symptoms of headache and dizziness demonstrate abnormalities of the vestibular system which can be measured quantitatively. Completion of comprehensive vestibular testing can help to guide diagnosis and strategies for intervention.

Age-related changes to vestibular heave and pitch perception and associations with postural control

Falls are a common cause of injury in older adults (OAs), and age-related declines across the sensory systems are associated with increased falls risk. The vestibular system is particularly important for maintaining balance and supporting safe mobility, and aging has been associated with declines in vestibular end-organ functioning. However, few studies have examined potential age-related differences in vestibular perceptual sensitivities or their association with postural stability. Here we used an adaptive-staircase procedure to measure detection and discrimination thresholds in 19 healthy OAs and 18 healthy younger adults (YAs), by presenting participants with passive heave (linear up-and-down translations) and pitch (forward-backward tilt rotations) movements on a motion-platform in the dark. We also examined participants' postural stability under various standing-balance conditions. Associations among these postural measures and vestibular perceptual thresholds were further examined. Ultimately, OAs showed larger heave and pitch detection thresholds compared to YAs, and larger perceptual thresholds were associated with greater postural sway, but only in OAs. Overall, these results suggest that vestibular perceptual sensitivity declines with older age and that such declines are associated with poorer postural stability. Future studies could consider the potential applicability of these results in the development of screening tools for falls prevention in OAs.

Simultaneous Multifrequency (SiMFy) Stimulus: A Novel and Reliable Stimulus for Frequency Tuning of Ocular Vestibular-Evoked Myogenic Potentials

BACKGROUND

Frequency tuning of ocular vestibular evoked myogenic potential (oVEMP) refers to the frequency of tone burst that produces the largest amplitude oVEMP. There is an ever-growing pool of published studies that found the frequency tuning of oVEMP distinctly different in Ménière's disease than the age-matched controls and benign paroxysmal positional vertigo. However, recording oVEMP in response to many frequencies makes an already lengthy vestibular test battery even more cumbersome and time-consuming.

PURPOSE

The aim of this study was to develop a novel time-saving stimulus that produces reliable results.

RESEARCH DESIGN

Prospective study.

STUDY SAMPLE

The study included 25 young, healthy adults.

DATA COLLECTION

The tone-bursts of 2000, 1500, 1000, 750, 500, and 250 Hz were generated and sequenced in this order to prepare a stimulus for simultaneous multifrequency (SiMFy) oVEMP. The response parameters of SiMFy and conventional oVEMP methods were compared.

RESULTS

No significant difference in peak-to-peak amplitude and frequency tuning existed between conventional and SiMFy oVEMP (p > 0.05). SiMFy had better test-retest reliability and was less time-consuming than the conventional oVEMP.

CONCLUSIONS

SiMFy is a time-saving and reliable stimulus for obtaining frequency tuning of oVEMP with no compromise on the outcomes. It can be immediately applied in most commercially available evoked potential systems with a facility for loading an external stimulus.

Simultaneous Multifrequency (SiMFy) Stimulus: A Novel and Reliable Stimulus for Frequency Tuning of Ocular Vestibular-Evoked Myogenic Potentials

Background Frequency tuning of ocular vestibular evoked myogenic potential (oVEMP) refers to the frequency of tone burst that produces the largest amplitude oVEMP. There is an ever-growing pool of published studies that found the frequency tuning of oVEMP distinctly different in Ménière's disease than the age-matched controls and benign paroxysmal positional vertigo. However, recording oVEMP in response to many frequencies makes an already lengthy vestibular test battery even more cumbersome and time-consuming.

Purpose The aim of this study was to develop a novel time-saving stimulus that produces reliable results.

Research Design Prospective study.

Study Sample The study included 25 young, healthy adults.

Data Collection The tone-bursts of 2000, 1500, 1000, 750, 500, and 250 Hz were generated and sequenced in this order to prepare a stimulus for simultaneous multifrequency (SiMFy) oVEMP. The response parameters of SiMFy and conventional oVEMP methods were compared.

Results No significant difference in peak-to-peak amplitude and frequency tuning existed between conventional and SiMFy oVEMP (p > 0.05). SiMFy had better test–retest reliability and was less time-consuming than the conventional oVEMP.

Conclusions SiMFy is a time-saving and reliable stimulus for obtaining frequency tuning of oVEMP with no compromise on the outcomes. It can be immediately applied in most commercially available evoked potential systems with a facility for loading an external stimulus.

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

Objectives

The first purpose of this study was to investigate the difference in the frequency of involvement of the superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) territories in general vestibular disorders, and to identify which IVN territory was more commonly involved in patients with IVN lesions. The second purpose was to investigate the correlation of the degree of each saccular and posterior semicircular canal (PSCC) dysfunction, as represented by the parameters of cervical vestibular evoked myogenic potential (cVEMP) and video head impulse test (vHIT), in patients with pathology of the IVN territory.

Methods

In total, 346 patients with dizziness who underwent the caloric test, cVEMP, and vHIT were enrolled. Canal weakness in the caloric test, interaural amplitude difference (IAD) of cVEMP, and vestibulo-ocular reflex gain of the vestibulo-ocular reflex gain of the posterior semicircular canal (p-VOR) in vHIT were analyzed.

Results

Among the enrolled patients, 15.6% had total vestibular nerve dysfunction, 14.5% had solely SVN dysfunction, and 29.5% had solely IVN dysfunction. Isolated saccular pathology was most common in patients with IVN pathology, followed by those with total IVN dysfunction and PSCC dysfunction. IAD and p-VOR were statistically well correlated, and the correlation was strongest in patients with both pathologic IAD and pathologic p-VOR (n=23, r=0.944), followed by patients with normal IAD and pathologic p-VOR (n=27, r=0.762) and patients with pathologic IAD and normal p-VOR (n=106, r=0.339).

Conclusion

Abnormal results were more common in vestibular tests investigating the IVN than in vestibular tests investigating the SVN in patients with general vestibular disorders. Isolated saccular pathology was more frequent than PSCC or combined pathology in patients with IVN dysfunction. Patients with abnormal p-VOR in vHIT had a higher probability of having both saccular and PSCC pathologies than patients with an abnormal IAD. This study describes the characteristics of vestibular-system subregions and provides guidance for clinically interpreting the combination of cVEMP and vHIT results.

Effects of Stimulus Polarity on Amplitude-Modulated Cervical Vestibular-Evoked Myogenic Potentials

BACKGROUND

 Traditional approaches to cervical vestibular-evoked myogenic potentials use a transient stimulus to elicit an onset response. However, alternate approaches with long duration stimuli may allow the development of new methodologies to better understand basic function of the vestibular system, as well as potentially developing new clinical applications.

PURPOSE

 The objective of this study was to examine the effects of stimulus polarity on response properties of amplitude-modulated cervical vestibular-evoked myogenic potentials (AMcVEMPs).

RESEARCH DESIGN

 Prospective, repeated-measures, within-subjects design.

STUDY SAMPLE

 Participants were 16 young, healthy adults (ages 21-38 years).

DATA COLLECTION AND ANALYSIS

 Amplitude-modulated tones, with carrier frequency of 500 Hz and modulation frequency of 37 Hz, were used to elicit AMcVEMPs. Responses were analyzed in three different stimulus polarity conditions: condensation, rarefaction, and alternating. The resulting data were analyzed for differences across polarity conditions.

RESULTS

 AMcVEMP amplitudes, both raw and corrected for tonic muscle activation, were equivalent across the different stimulus phase conditions. In addition, response signal-to-noise ratio and phase coherence were equivalent across the different phases of the stimulus.

CONCLUSION

 Analyses of AMcVEMPs are stable when the carrier frequency starting phase is altered and the phase of the temporal envelope is constant.

Nonlinearity in bone-conducted amplitude-modulated cervical vestibular evoked myogenic potentials: Harmonic distortion products

Otolith organs of the balance system, the saccule and utricle, encode linear acceleration. Integrity of the saccule is commonly assessed using cervical vestibular evoked myogenic potentials (cVEMPs) arising from an inhibitory reflex along the vestibulospinal pathway. Conventional approaches to eliciting these responses use brief, transient sounds to elicit onset responses. Here we used long-duration amplitude-modulated (AM) tones to elicit cVEMPs (AMcVEMPs) and analyzed their spectral content for evidence of nonlinear processing consistent with known characteristics of vestibular hair cells. Twelve young adults (ages 21-25) with no hearing or vestibular pathologies participated in this study. AMcVEMPs were elicited by bone-conducted AM tones with a 500 Hz carrier frequency. Eighteen modulation frequencies were used between 7 and 403 Hz. All participants had robust distortion products at harmonics of the modulation frequency. Total harmonic distortion ranged from approximately 10 to 80%. AMcVEMPs contain harmonic distortion products consistent with vestibular hair cell nonlinearities, and this new approach to studying the otolith organs may provide a non-invasive, in vivo method to study nonlinearity of vestibular hair cells in humans.

Discrimination of vestibular function based on inertial sensors

BACKGROUND AND OBJECTIVE

Vestibular dysfunction, as a common disease or symptom, can cause abnormalities in gait and balance. Since the existing detection methods are static detection and cannot obtain the dynamic vestibular information of patients, this paper proposes a simple method for detecting vestibular dysfunction based on gait signals of subjects.

METHODS

In our study, the walking patterns of dynamic gait index (DGI) and inertial sensor were adopted for the data acquisition. Time-domain, frequency-domain and non-linear features were extracted from inertial sensor signals. Then the Relief algorithm was used for feature selection. Two classifiers, Support Vector Machine (SVM) and Random Forest (RF), were used to classify the patients with vestibular dysfunction and the healthy controls.

RESULTS

The highest accuracy of 84.79% was achieved based on magnetometer features and SVM classifier. To further improve classification results, features of three sensor signals were combined and applied to two classifiers. Combined features and RF classifier achieved a classification accuracy of 86.5%.

CONCLUSION

The detection of vestibular dysfunction based on inertial sensors might be simple, accurate and easy to implement in clinical examination, which provides a new method for the clinical diagnosis of vestibular function.

REM sleep without atonia and vestibular-evoked myogenic potentials: clinical brainstem dysfunction in early-stage Parkinson's disease and isolated REM sleep behavior disorder

OBJECTIVE

To determine whether the onset of rapid eye movement (REM) sleep behavior disorder (RBD) is associated with changes in brainstem neuronal pathway dysfunction as reflected by vestibular-evoked myogenic potentials (VEMPs) and to evaluate associations between VEMPs and REM sleep without atonia (RSWA) in patients with early-stage Parkinson's disease (PD) and isolated RBD (iRBD).

METHODS

Eighty-two early-stage PD patients, 40 iRBD patients, and 41 healthy control individuals underwent one-night video-polysomnography (vPSG) and VEMPs examination. We compared cervical (cVEMP), ocular (oVEMP), and masseter (mVEMP) VEMP parameters among PD with RBD (PD + RBD), PD without RBD (PD-RBD), iRBD, and control groups and analyzed correlations between VEMPs and RSWA in PD and iRBD groups.

RESULTS

The PD + RBD group showed delays in bilateral cVEMP (Lp13, Ln23, Rn23: all p < 0.05) and oVEMP (Ln10, Rn10, Rp15: all p < 0.05) peak latencies compared with the PD-RBD group. Total cVEMP scores were higher in the PD + RBD group than in the iRBD group (p = 0.033). In PD patients, phasic RSWA was correlated with total cVEMP scores (p = 0.003), and tonic RSWA was correlated with left oVEMP scores (p = 0.013).

CONCLUSIONS

Brainstem neurophysiology as evidenced by altered VEMPs in patients with PD and iRBD could reflect disease evolvement. Moreover, VEMPs alterations may vary depending on the presence of RBD in PD patients. The associations between altered RSWA and VEMP parameters highlight the meaningfulness of detecting brainstem dysfunction in early-stage PD.

Asymmetry and tuning shift of the cervical vestibular evoked myogenic potential indicate saccular dysfunction in idiopathic normal pressure hydrocephalus

OBJECTIVE

The purpose of this study was to investigate the effects of excessive cerebrospinal fluid (CSF) retention on the peripheral vestibular function and the inner ear fluid in patients with idiopathic normal pressure hydrocephalus (iNPH).

METHODS

In 25 patients with iNPH (14 females, age 65-88 years), cervical vestibular evoked myogenic potential (cVEMP) was measured before the spinal tap test. The asymmetry ratios (ARs) and tuning properties in 500 Hz and 1,000 Hz short-tone burst stimuli of cVEMP were evaluated. Furthermore, cVEMP was measured in an age-matched control group of 12 non-iNPH patients.

RESULTS

Seven (28%) iNPH patients exhibited a cVEMP asymmetry (AR > 33%). cVEMP tuning was significantly shifted to a higher frequency in the iNPH group than in the age-matched control group.

CONCLUSIONS

One-fourth of patients with iNPH had obvious saccular dysfunction. A high rate of a shift in cVEMP tuning in the iNPH group indicated that excessive CSF accumulation propagated to the endolymph and perilymph.

SIGNIFICANCE

Saccular dysfunction might be one of the possible causes of imbalance in iNPH, and the shift in cVEMP tuning may be a determining factor in the diagnosis and treatment strategy.

Using Narrow Band CE-Chirps to Elicit Cervical Vestibular Evoked Myogenic Potentials

Objectives:

To compare the effects of Narrow band CE-Chirps (NB CE-Chirps) and tone bursts (TBs) at 500 Hz and 1000 Hz on the amplitudes and latencies in cervical vestibular evoked myogenic potentials (cVEMPs).

Design:

Thirty-one healthy adult volunteers of varying ages were tested by air conduction at 95 dB nHL. Recording conditions were randomized for each participant and each modality was tested twice.

Results:

NB CE-Chirps showed larger corrected amplitudes than TBs at 500 Hz (p < 0.001) which were themselves larger than NB CE-Chirps and TBs at 1000 Hz (p < 0.001). In older volunteers, NB CE-Chirps 500 and 1000 Hz had significantly higher response rates than TBs 500 Hz (p = 0.039). A negative correlation was observed between the corrected amplitudes and the age of the participants regardless of the stimulus and the frequency studied. The p13 and n23 latencies were not correlated with the age of the subjects.

Conclusions:

NB CE-Chirps at 500 Hz improved the corrected amplitudes of waveforms in cVEMPs as a result of a better frequency specificity compared with TBs. In the elderly, eliciting cVEMPs at a frequency of 1000 Hz might not be necessary to improve response rates with NB CE-Chirps. Additional studies including a higher number of healthy participants and patients with vestibular disorders are required to confirm these observations.

Vestibular Perceptual Thresholds in Older Adults With and Without Age-related Hearing Loss

OBJECTIVES

Older adults with age-related hearing loss (ARHL) are at greater risk of falling and have greater mobility problems than older adults with normal hearing (NH). The underlying cause of these associations remains unclear. One possible reason is that age-related declines in the vestibular system could parallel those observed in the auditory system within the same individuals. Here, we compare the sensitivity of vestibular perceptual abilities (psychophysics), vestibular end-organ functioning (vestibular evoked myogenic potentials and video head impulse tests), and standing balance (posturography) in healthy older adults with and without ARHL.

DESIGN

A total of 46 community-dwelling older adults, 23 with ARHL and 23 with NH, were passively translated in heave (up and down) and rotated in pitch (tilted forward and backward) in the dark using a motion platform. Using an adaptive staircase psychophysical procedure, participants' heave and pitch detection and discrimination thresholds were determined. In a posturography task, participants' center of pressure (COP) path length was measured as they stood on a forceplate with eyes open and closed, on firm and compliant surfaces, with and without sound suppression. Baseline motor, cognitive, and sensory functioning, including vestibular end-organ function, were measured.

RESULTS

Individuals with ARHL were less sensitive at discriminating pitch movements compared to older adults with NH. Poorer self-reported hearing abilities were also associated with poorer pitch discrimination. In addition to pitch discrimination thresholds, lower pitch detection thresholds were significantly associated with hearing loss in the low-frequency range. Less stable standing balance was significantly associated with poorer vestibular perceptual sensitivity.

DISCUSSION

These findings provide evidence for an association between ARHL and reduced vestibular perceptual sensitivity.

Similarities and Differences Between Vestibular and Cochlear Systems - A Review of Clinical and Physiological Evidence

The evoked response to repeated brief stimuli, such as clicks or short tone bursts, is used for clinical evaluation of the function of both the auditory and vestibular systems. One auditory response is a neural potential - the Auditory Brainstem Response (ABR) - recorded by surface electrodes on the head. The clinical analogue for testing the otolithic response to abrupt sounds and vibration is the myogenic potential recorded from tensed muscles - the vestibular evoked myogenic potential (VEMP). VEMPs have provided clinicians with a long sought-after tool - a simple, clinically realistic indicator of the function of each of the 4 otolithic sensory regions. We review the basic neural evidence for VEMPs and discuss the similarities and differences between otolithic and cochlear receptors and afferents. VEMPs are probably initiated by sound or vibration selectively activating afferent neurons with irregular resting discharge originating from the unique type I receptors at a specialized region of the otolithic maculae (the striola). We review how changes in VEMP responses indicate the functional state of peripheral vestibular function and the likely transduction mechanisms allowing otolithic receptors and afferents to trigger such very short latency responses. In section "ELECTROPHYSIOLOGY" we show how cochlear and vestibular receptors and afferents have many similar electrophysiological characteristics [e.g., both generate microphonics, summating potentials, and compound action potentials (the vestibular evoked potential, VsEP)]. Recent electrophysiological evidence shows that the hydrodynamic changes in the labyrinth caused by increased fluid volume (endolymphatic hydrops), change the responses of utricular receptors and afferents in a way which mimics the changes in vestibular function attributed to endolymphatic hydrops in human patients. In section "MECHANICS OF OTOLITHS IN VEMPS TESTING" we show how the major VEMP results (latency and frequency response) follow from modeling the physical characteristics of the macula (dimensions, stiffness etc.). In particular, the structure and mechanical operation of the utricular macula explains the very fast response of the type I receptors and irregular afferents which is the very basis of VEMPs and these structural changes of the macula in Menière's Disease (MD) predict the upward shift of VEMP tuning in these patients.

Response characteristics of vestibular evoked myogenic potentials recorded over splenius capitis in young adults and adolescents

BACKGROUND AND OBJECTIVES

Examine vestibular evoked myogenic potential (VEMP) responses recorded from surface electrodes over Splenius Capitis (SPC) in a seated position.

SPECIFIC AIMS

(1) validate response characteristics of VEMP recordings from surface electrodes over Sternocleidomastoid (SCM) and over SCP and (2) assess age effects on responses in adolescents and young adults.

MATERIALS AND METHODS

Simultaneous surface VEMP was recorded bilaterally from electrodes placed over the dorsal neck musculature at a location known from previous work to record from SPC in 15 healthy participants during trials with head rotation toward and away from the stimulated ear. VEMP was also recorded from electrodes over SCM, ipsilateral to the stimulus ear, in the same participants in a supine, head lift/turn position.

RESULTS

Response amplitudes significantly increased with contraction strength and decreased with age. Participants were able to maintain sufficient contraction strength (amplitude) with head rotation to reliably measure over SPC. Normalized response amplitudes measured from electrodes over contralateral SPC were largest with head rotation contralateral to the stimulus ear. Normalized amplitudes and peak latencies were comparable to the same measures from SCM obtained in supine, head lift/turn position.

CONCLUSIONS

Otolith generated myogenic responses can be recorded seated from electrodes over the dorsal neck with head rotation contralateral to the stimulus ear. In this position, contralateral recordings are consistent with responses known from previous work to arise from SPC; ipsilateral recordings may include crosstalk from activated muscles nearby, including ipsilateral SCM. Overall, techniques targeting contralateral SPC during contralateral head turn may provide additional methods of recording VEMPs.

Influence of Cochlear Implantation on Vestibular Function in Children With an Enlarged Vestibular Aqueduct

Background: Cochlear implantation (CI) is becoming increasingly used in the rehabilitation of hearing-impaired patients. Children with an enlarged vestibular aqueduct (EVA) need CI for severe or profound hearing loss, with excellent outcomes in hearing rehabilitation. However, vestibular function influenced by CI in children with EVA has not been clarified. We compared the characteristics of vestibular function in implanted children with EVA and those with a normal cochlea.

Methods: In this retrospective case-control study, 16 children with large vestibular aqueduct syndrome (LVAS) and 16 children with a normal cochlea were recruited as the Study and Control Group, respectively. All children (mean age, 10.3 ± 4.4 years) had bilateral profound sensorineural hearing loss (SNHL) and normal pre-operative vestibular functions and underwent unilateral CI. Otolith and canal functions were assessed before CI and 12 months thereafter. Cervical vestibular-evoked myogenic potential (cVEMP), ocular vestibular-evoked myogenic potential (oVEMP), and video head impulse test (vHIT) were evaluated.

Results: Full insertion of the electrode array was achieved in all the cases. Preoperatively, no significant differences in parameters in cVEMP between the Study and Control Group were revealed (p > 0.05). In pre-operative oVEMP, shorter N1 latencies (p = 0.012), shorter P1 latencies (p = 0.01), and higher amplitudes (p = 0.001) were found in the Study than in the Control Group. The Study Group had shorter P1 latency in cVEMP (p = 0.033), and had lower amplitude in oVEMP after implantation (p = 0.03). Statistically significant differences were not found in VOR gains of all three semicircular canals before and after surgery (p > 0.05). VEMP results revealed that the Control Group had significantly lower deterioration rates after CI (p < 0.05). The surgical approach and electrode array had no statistically significant influence on the VEMP results (p > 0.05).

Conclusion: oVEMP parameters differed between children with EVA and children with a normal cochlea before surgery. Systematic evaluations before and after CI showed that otolith function was affected, but all three semicircular canals functions were essentially undamaged after implantation. In contrast to subjects with a normal cochlea, children with EVA are more likely to preserve their saccular and utricular functions after CI surgery. Possible mechanisms include less pressure-related damage, a reduced effect in terms of the air-bone gap (ABG), or more sensitivity to acoustic stimulation.

Age Effects of Bone Conduction Vibration Vestibular-evoked Myogenic Potentials (VEMPs) Using B81 and Impulse Hammer Stimuli

OBJECTIVE

Recently developed, the Radioear B81 bone oscillator allows for higher bone conduction vibration output; however, normative data are lacking regarding its use in vestibular-evoked myogenic potential (VEMP) testing. The purpose of this study was to examine the effect of age on cervical and ocular VEMP (c- and oVEMP) responses using the B81 and to compare with air conduction stimuli (ACS) and impulse hammer (IH) VEMP response characteristics.

DESIGN

c- and oVEMP were completed with ACS, B81, and IH stimuli in healthy participants (age range = 10 to 87 years, n = 85).

RESULTS

Regardless of stimulus type, c- and oVEMP amplitudes and response rates decreased with age. For cVEMP response rates, ACS performed better or equal to B81, which was superior to the IH. For cVEMP corrected amplitude, ACS had significantly higher amplitudes compared with B81 and IH. There was no difference in cVEMP corrected amplitude between B81 and IH. For oVEMP, response rates were comparable between stimuli with the largest disparity in response rates occurring in the oldest groups where IH outperformed both ACS and B81. For oVEMP amplitude, IH had significantly higher amplitudes compared with B81 and ACS. There was no difference in oVEMP amplitude between B81 and ACS.

CONCLUSIONS

Age significantly affected c- and oVEMP amplitudes regardless of stimulus type (ACS, B81, IH). All stimuli are appropriate for eliciting c- and oVEMP in the young individuals. While ACS resulted in higher cVEMP corrected amplitudes, either ACS or B81 are appropriate for older individuals. However, for oVEMPs, higher response rates and larger amplitudes were noted for IH followed by B81 and ACS. Overall, the B81 performed well across the lifespan for c- and oVEMPs and may be a reasonable bone conduction vibration option for patients with absent ACS VEMPs, but at this time is not recommended as a replacement to ACS.

Optimizing Ocular Vestibular Evoked Myogenic Potentials With Narrow Band CE-Chirps

OBJECTIVES

To evaluate the effects of narrow band CE-Chirp (NB CE-Chirp) on the amplitudes and latencies in ocular vestibular evoked myogenic potentials (oVEMPs) at 500 and 1000 Hz in comparison with tone burst (TB).

DESIGN

Twenty-one healthy volunteers were included in the study and tested in air conduction with a "belly-tendon" montage. Recording conditions were randomized for each participant and each modality was tested twice to check the reproducibility of the procedure.

RESULTS

NB CE-Chirps at 500 Hz revealed larger n1-p1 amplitudes than 500 Hz TBs (p = .001), which were also larger than NB CE-Chirps and TBs at 1000 Hz (p = .022, p < .001, respectively). Besides, n1 and p1 latencies were shorter in NB CE-Chirp than in TB at 500 Hz (p < .001) and 1000 Hz (p < .001). The older the participants, the lower the amplitudes (p = .021, p = .031) and the longer the n1 (p = .030, p = .025) and p1 latencies (p < .001, p < .001) in 500 Hz NB CE-Chirps and 500 Hz TBs. Interaural asymmetry ratios were slightly higher in 500 Hz NB CE-Chirps as compared to 500 Hz TBs (p = .013).

CONCLUSIONS

NB CE-Chirps at 500 Hz improved the amplitudes of waveforms in oVEMPs. As for TBs with clicks before, enhancing oVEMPs amplitudes is an essential step to distinguish a healthy person from a patient with either utricular or its related pathways disorder and potentially minimize the risk of cochlear damages. Additional studies including a higher number of healthy participants and patients with vestibular disorders are required to confirm this hypothesis. The large interindividual variability of interaural asymmetry ratios in NB CE-Chirp and in TB at 500 Hz could be explained by the selected montage.

Effect of advancing age on inter-frequency amplitude ratio of ocular vestibular evoked myogenic potentials

OBJECTIVE

The inter-frequency amplitude ratio (IFAR) is the ratio of the amplitude of 1000-Hz tone-burst evoked ocular vestibular evoked myogenic potential (oVEMP) to the 500 Hz tone-burst evoked oVEMP. Since IFAR is an amplitude-based parameter, and the amplitudes of oVEMP for different frequencies are differentially affected by ageing, IFAR could potentially be affected by the ageing process. Therefore, we aimed to examine the effects of ageing on the IFAR of oVEMPs.

DESIGN

Multiple static groups comparison.

STUDY SAMPLE

We recorded oVEMPs for 500 Hz and 1000 Hz tone-bursts from 270 healthy individuals, each included in one of the six age groups.

RESULTS

The IFAR was significantly larger in the ≥60 years age group than the age groups up to 49 years. Furthermore, the IFAR in the 50-59 years age group was significantly larger than all the other age groups up to 39 years. There was a significant positive correlation between age and IFARs (p < 0.01).

CONCLUSIONS

IFAR, a sensitive tool in the test battery for the diagnosis of Meniere's disease, is affected even in healthy individuals due to ageing; hence its cautious interpretation is recommended when evaluating adults >50 years of age who are suspected of having Meniere's disease.

Comparison of Bone-Conducted Cervical VEMPs Elicited by B71 and B81 Bone Vibrators

OBJECTIVE

A variety of stimulus delivery methods can elicit vestibular evoked myogenic potentials (VEMPs). The current study compared bone conduction (BC) cervical VEMPs (cVEMPs) across two different clinical bone vibrators. It was hypothesized that the B81 transducer would be more effective for producing larger BC-cVEMP peak to peak amplitudes due to its low-frequency advantages in pure-tone audiometry applications.

DESIGN

Twenty young adults under the age of 40 years with no reported history of hearing or balance disorders participated in the study. BC cVEMPs were elicited using two clinical bone transducers: the Radioear B71 bone vibrator and the Radioear B81 bone vibrator. Both transducers were calibrated using the acoustic method of calibration before data collection, and the linear dynamic range of the transducers was determined. Participants were asked to sit and match a fixed electromyography (EMG) target level of 100 µV, while BC cVEMPs were recorded using stimulus frequencies of 250, 500, and 750 Hz.

RESULTS

Statistically significant differences in raw amplitude at 250 and 750 Hz between the B71 and B81 were observed; the B71 produced larger peak to peak amplitudes over the B81. At 500 Hz, larger amplitudes were observed with the B71, but results were not statistically significant. The B71 produced significantly lower cVEMP thresholds at all three frequencies. Across both transducers, 500 Hz produced the largest peak to peak amplitude compared with 250 and 750 Hz. Peak to peak amplitude did not increase above 55 dB nHL for 250 and 500 Hz, but amplitude continued to increase at 750 Hz.

DISCUSSION

The present study found statistically significant differences in BC-cVEMP amplitude and threshold between the B71 and B81, but results were not what we hypothesized. In general, the B71 elicited larger BC-cVEMP amplitudes and lower thresholds compared with the B81. Additionally, 500 Hz was found to be the best frequency for both BC transducers, contrasting previous studies suggesting lower frequencies yield larger BC-cVEMP amplitudes. It is possible that these average differences could also be clinically significant when looking at individual amplitude differences. Larger peak to peak amplitudes at 500 Hz may be partially due to the underlying physical levels used in the current study, as well as the output spectra of the transducers, and may explain the larger response amplitudes observed at 500 Hz compared with 250 Hz.

Case Report: Auditory Neuropathy and Central Auditory Processing Deficits in a Neuro-Otological Case-Study of Infratentorial Superficial Siderosis

Hearing and balance impairment are the most frequently reported features of infratentorial (classical) superficial siderosis (iSS). There are few comprehensive descriptions of audiovestibular function in iSS and therefore limited understanding of the affected segment(s) of the audiovestibular pathway. In addition, monitoring disease progression and response to treatment is challenging and currently mainly guided by subjective patient reports and magnetic resonance imaging. To the best of our knowledge, there have been no previous reports assessing central auditory function in iSS. We describe such findings in a patient with iSS in an attempt to precisely localize the site of the audiovestibular dysfunction, determine its severity and functional impact. We confirm the presence of (asymmetrical) auditory neuropathy and identify central auditory processing deficits, suggesting involvement of the central auditory pathway beyond the brainstem. We correlate the audiological and vestibular findings with self-report measures and the siderosis appearances on brain magnetic resonance images.

Diagnosing vestibular hypofunction: an update

Unilateral or bilateral vestibular hypofunction presents most commonly with symptoms of dizziness or postural imbalance and affects a large population. However, it is often missed because no quantitative testing of vestibular function is performed, or misdiagnosed due to a lack of standardization of vestibular testing. Therefore, this article reviews the current status of the most frequently used vestibular tests for canal and otolith function. This information can also be used to reach a consensus about the systematic diagnosis of vestibular hypofunction.

Quantifying the effects of electrode placement and montage on measures of cVEMP amplitude and muscle contraction

BACKGROUND

The cervical vestibular evoked myogenic potential (cVEMP) can be affected by the recording parameters used to quantify the response.

OBJECTIVE

We investigated the effects of electrode placement and montage on the variability and symmetry of sternocleidomastoid (SCM) contraction strength and cVEMP amplitude.

METHODS

We used inter-side asymmetries in electrode placement to mimic small clinical errors in twenty normal subjects. cVEMPs were recorded at three active electrode sites and referred to the distal SCM tendon (referential montages: upper, conventional and lower). Additional bipolar montages were constructed offline to measure SCM contraction strength using closely-spaced electrode pairs (bipolar montages: superior, lower and outer).

RESULTS

The conventional montage generally produced the largest cVEMP amplitudes (P < 0.001). SCM contraction strength was larger for referential montages than bipolar ones (P < 0.001). Inter-side electrode position errors produced large variations in cVEMP and SCM contraction strength asymmetries in some subjects, producing erroneous abnormal test results.

CONCLUSION

Recording locations affect cVEMP amplitude and SCM contraction strength. In most cases, small changes in electrode position had only minor effects but, in a minority of subjects, the different montages produced large changes in cVEMP and contraction amplitudes and asymmetry, potentially affecting test outcomes.

Association between vestibular dysfunction and findings of horizontal head-shaking and vibration-induced nystagmus

BACKGROUND

The association between vestibular function and findings of horizontal head-shaking nystagmus (HHSN) and vibration-induced nystagmus (VIN) tests is not well understood.

OBJECTIVE

To investigate the association between function in the five distinct vestibular end organs and findings of these nystagmus tests.

METHODS

We retrospectively reviewed the medical records of 50 patients with vestibular diseases who underwent HHSN testing, VIN testing, video head impulse testing (vHIT), cervical vestibular evoked myogenic potential testing to air-conducted sound (ACS cVEMP) and ocular VEMP testing to ACS (ACS oVEMP). We performed mixed-effects logistic regression analyses to see whether age, sex or the presence of nystagmus in HHSN or VIN have an association with the presence of peripheral vestibular dysfunction on the opposite side to the direction of nystagmus.

RESULTS

The presence of HHSN had a significant association with abnormal vHIT in the lateral semicircular canal (LSCC) on the opposite side to the direction of nystagmus. The presence of VIN had a significant association with abnormal vHIT in all the SCCs and abnormal ACS oVEMP on the opposite side to the direction of nystagmus.

CONCLUSIONS

HHSN had an association with LSCC dysfunction alone. VIN had an association with dysfunction in all the SCCs and the utricle.

Topography of the lesion in idiopathic sudden sensorineural hearing loss

INTRODUCTION

Etiology of ISSNHL includes cessation of vascular perfusion, viral infection and cochlear membrane injury. Precise location of injury should be defined for a target-oriented treatment. Vestibular complaints in ISSNHL are hypothesized as involvement of vestibule. Vestibular complaints can be either due to involvement of inner ear or neural tract at any level.

OBJECTIVES

In the present study we aimed to demonstrate involvement of vestibular organs in the absence of vestibular symptoms. It was aimed to evaluate superior and inferior vestibular neural pathways.

METHODS

c-vemp and o-vemp were applied to patients suffering ISSNHL without vertigo. Pure tone averages, audiogram configurations, degree of hearing loss were analyzed. Latencies of P1 and N1 waves, amplitudes of P1-N1 waves were evaluated. Asymmetrical vemp wave patterns were compared between two ears regarding difference of PTA.

RESULTS

Latencies of c-vemp waves were longer and amplitudes were smaller. o-vemp parameters were similar on both sides. Positive correlation was observed between c-vemp latencies and degree hearing loss.

CONCLUSION

Inferior vestibular nerve pathway is affected in the absence of vertigo in ISSNHL with spared superior vestibular nerve pathway. Damage in IVN pathway correlates with degree of ISSNHL.

Cervical and ocular vestibular evoked myogenic potentials in determining nerve division involvement in patients with a tumor located in the internal auditory canal

OBJECTIVES

The study aimed at the analysis of the parameters of acoustic cervical and ocular vestibular evoked myogenic potentials (AC-cVEMP and AC-oVEMP) response in patients with a confirmed tumor located in the internal auditory canal. It also aimed to assess to what degree a combination of these tests may be of benefit in the preoperative indication of the affected nerve division via preoperative determination whether the tumor originated from the superior or inferior division of the vestibular nerve, both divisions, or if it originated from a different nerve in the internal auditory canal.

METHODS

The study group included 50 patients. Preoperative MRI scans were used to measure tumor diameter. AC-cVEMP and AC-oVEMP testing were performed before tumor resection. The surgeon was asked for a detailed description of the tumor origin.

RESULTS

The corrected amplitude of cVEMP was significantly lower on the tumor side than on the non-affected side and in the control group. The corrected Asymmetry Ratio (AR) of cVEMPs in patients with the tumor was significantly elevated above the reference values with the mean being 58.29% and the mean AR of oVEMPs in patients the tumor was 71.78% which made both results significantly higher than in the control group. Neither cVEMP nor oVEMP latency was significantly correlated with tumor size. Data obtained from cVEMP and oVEMP tests was an effective indicator of tumor origin in 74% of patients showing which division (or both divisions) of the VIII^th nerve was affected in comparison with information obtained from the surgeon.

CONCLUSIONS

The combined use of AC-cVEMP and AC-oVEMP tests may be useful in surgical planning in patients the tumor located in the internal auditory canal, providing a highly probable determination of the division of the affected nerve. Such information is valuable for the surgeon as it offers additional knowledge about the tumor before the procedure. cVEMP and oVEMP results may not be used as the basis for the calculation of tumor size in patients.

Evidence-based diagnostic use of VEMPs : From neurophysiological principles to clinical application

BACKGROUND

Vestibular evoked myogenic potentials (VEMPs) are increasingly being used for testing otolith organ function.

OBJECTIVE

This article provides an overview of the anatomical, biomechanical and neurophysiological principles underlying the evidence-based clinical application of ocular and cervical VEMPs (oVEMPs and cVEMPs).

MATERIAL AND METHODS

Systematic literature search in PubMed until April 2019.

RESULTS

Sound and vibration at a frequency of 500 Hz represent selective vestibular stimuli for the otolith organs. The predominant specificity of oVEMPs for contralateral utricular function and of cVEMPs for ipsilateral saccular function is defined by the different central projections of utricular and saccular afferents. VEMPs are particularly useful in the diagnosis of superior canal dehiscence and otolith organ specific vestibular dysfunction and as an alternative diagnostic approach in situations when video oculography is not possible or useful.

CONCLUSION

The use of VEMPs is a simple, safe, reliable and selective test of dynamic function of otolith organs.

Ocular Vestibular-Evoked Myogenic Potential Amplitudes Elicited at 4 kHz Optimize Detection of Superior Semicircular Canal Dehiscence

Introduction: High-resolution temporal bone computed tomography (CT) is considered the gold standard for diagnosing superior semicircular canal dehiscence (SCD). However, CT has been shown over-detect SCD and provide results that may not align with patient-reported symptoms. Ocular vestibular-evoked myogenic potentials (oVEMPs)—most commonly conducted at 500 Hz stimulation—are increasingly used to support the diagnosis and management of SCD. Previous research reported that stimulation at higher frequencies such as 4 kHz can have near-perfect sensitivity and specificity in detecting radiographic SCD. With a larger cohort, we seek to understand the sensitivity and specificity of 4 kHz oVEMPs for detecting clinically significant SCD, as well as subgroups of radiographic, symptomatic, and surgical SCD. We also investigate whether assessing the 4 kHz oVEMP n10-p15 amplitude rather than the binary n10 response alone would optimize the detection of SCD.

Methods: We conducted a cross-sectional study of patients who have undergone oVEMP testing at 4 kHz. Using the diagnostic criteria proposed by Ward et al., patients were determined to have SCD if dehiscence was confirmed on temporal bone CT by two reviewers, patient-reported characteristic symptoms, and if they had at least one positive vestibular or audiometric test suggestive of SCD. Receiver operating characteristic (ROC) analysis was conducted to identify the optimal 4 kHz oVEMP amplitude cut-off. Comparison of 4 kHz oVEMP amplitude across radiographic, symptomatic, and surgical SCD subgroups was conducted using the Mann-Whitney U test.

Results: Nine hundred two patients (n, ears = 1,804) underwent 4 kHz oVEMP testing. After evaluating 150 temporal bone CTs, we identified 49 patients (n, ears = 61) who had radiographic SCD. Of those, 33 patients (n, ears = 37) were determined to have clinically significant SCD. For this study cohort, 4 kHz oVEMP responses had a sensitivity of 86.5% and a specificity of 87.8%. ROC analysis demonstrated that accounting for the inter-amplitude of 4 kHz oVEMP was more accurate in detecting SCD than the presence of n10 response alone (AUC 91 vs. 87%). Additionally, using an amplitude cut-off of 15uV reduces false positive results and improves specificity to 96.8%. Assessing 4 kHz oVEMP response across SCD subgroups demonstrated that surgical and symptomatic SCD cases had significantly higher amplitudes, while radiographic SCD cases without characteristic symptoms had similar amplitudes compared to cases without evidence of SCD.

Conclusion: Our results suggest that accounting for 4 kHz oVEMP amplitude can improve detection of SCD compared to the binary presence of n10 response. The 4 kHz oVEMP amplitude cut-off that maximizes sensitivity and specificity for our cohort is 15 uV. Our results also suggest that 4 kHz oVEMP amplitudes align better with symptomatic SCD cases compared to cases in which there is radiographic SCD but no characteristic symptoms.

A New Proposal for Severity Evaluation of Menière's Disease by Using the Evidence From a Comprehensive Battery of Auditory and Vestibular Tests

To date, no widely accepted criteria exist to quantify the severity of Menière's disease (MD) by using vestibular tests. This study aimed to compare association of hearing loss and vertigo severity with association of accurate assessments of vestibular function and the vertigo severity. The severity of vertigo was documented by a comprehensive medical history with number of vertigo attacks in the past 6 months and a Dizziness Handicap Inventory (DHI) questionnaire. The involvement of vestibular organs was verified by audio-vestibular tests in 80 definite MD patients. Correlations between DHI scores, number of vertigo attacks in the past 6 months, audio-vestibular function, and the number of involved vestibular end organs were evaluated. We show that there are no significant differences in either severity of vertigo or laboratory results across the degree of hearing loss. Furthermore, the number of involved vestibular end organs was significantly correlated with vestibulo-ocular reflex gain in anterior and posterior canal video head impulse test (vHIT), interaural asymmetry ratio in vestibular-evoked myogenic potentials (VEMPs), and number of vertigo attacks in the past 6 months and DHI score. The vestibulo-ocular reflex gain in the rotatory chair test (RCT) was significantly correlated with the DHI Physical scores and number of involved vestibular end organs at 0.08 Hz. These results indicate that hearing loss is a poor indicator of vertigo severity in MD whereas the number of involved vestibular end organs may serve as an objective measure for MD progress. A battery of vestibular tests targeting different sensor organs is a complementary method for evaluating inner ear deficits and may aid in "grading" the severity of MD.