Safe Levels of Acoustic Stimulation for Vemps: Comment on "Sudden Bilateral Hearing Loss After Cervical and Ocular Vestibular Evoked Myogenic Potentials"

The Validation of a Simultaneous Ocular and Cervical VEMP Recording Protocol to Unilateral AC Stimuli

INTRODUCTION

A simultaneous recording of cervical and ocular vestibular evoked myogenic potential (sVEMP) to unilateral air-conducted (AC) stimulation reduces the test time and halves the sound load.

MATERIALS AND METHODS

The sVEMP has been compared with the conventional sequential unilateral AC cervical and ocular VEMP in a consecutive cohort of 120 subjects attending the vestibular laboratory. The stimulus was a 500-Hz 6-ms tone burst, at 130 dB peSPL for sequential recordings but at 125 dB for the added sVEMP, for cumulative sound load containment. Amplitudes, latencies, and amplitude asymmetry ratios (ARs) were the parameters included in analysis.

RESULTS

Relevant results were as follows: 1) significantly lower amplitudes in sVEMP versus VEMP (ocular recordings, median = 2.90 [IQR = 0-4.98] vs. 4.15 [1.73-8.98] μV, p < 0.001; cervical, 0.84 [0.30-1.69] vs. 1.36 [0.60-2.30], p < 0.001; electromyography scaled values); 2) 10% lower response rate at cervical recordings and 11% at ocular recordings in sVEMP, particularly in older subjects; 3) significant correlations between cervical amplitudes ( rs = 0.88, p < 0.001), ocular amplitudes ( rs = 0.71, p < 0.001), peak latencies ( rs = 0.36-0.67, p < 0.001), and ARs (ocular, rs = 0.56; cervical, rs = 68, p < 0.001); and 4) good agreement in pathological AR detection (cervical recordings, Cohen's κ = 0.649, p < 0.001; ocular, κ = 0.589, p < 0.001).

DISCUSSION

AC sVEMP showed good correlation/agreement with sequential AC VEMP. Test time containment and halved sound load are clinical adds in sVEMP, opening to its use as laboratory standard. However, AC sVEMP presented reduced amplitudes and response rates, secondary to the reduced AC stimulation used in this study to allow checking of the null responses and the pathological ARs at AC sVEMP with conventional AC VEMP.

Neurological update: neuro-otology 2023

Much has changed since our last review of recent advances in neuro-otology 7 years ago. Unfortunately there are still not many practising neuro-otologists, so that most patients with vestibular problems need, in the first instance, to be evaluated and treated by neurologists whose special expertise is not neuro-otology. The areas we consider here are mostly those that almost any neurologist should be able to start managing: acute spontaneous vertigo in the Emergency Room-is it vestibular neuritis or posterior circulation stroke; recurrent spontaneous vertigo in the office-is it vestibular migraine or Meniere's disease and the most common vestibular problem of all-benign positional vertigo. Finally we consider the future: long-term vestibular monitoring and the impact of machine learning on vestibular diagnosis.

Influence of the Electrode Montage to Detect Ocular Vestibular Evoked Myogenic Potentials

OBJECTIVE

To compare ocular vestibular evoked myogenic potentials (oVEMPs) obtained with three different electrode montages (infra-orbital vs belly-tendon vs chin) in a group of healthy subjects. To assess the electrical activity recorded at the level of the reference electrode in the belly-tendon and chin montages.

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral center.

PATIENTS

Twenty-five healthy adult volunteers.

INTERVENTIONS

Each ear was tested separately via air-conducted sound (500 Hz Narrow Band CE-Chirps at 100 dB nHL) for recording contralateral myogenic responses. Recording conditions were randomized.

MAIN OUTCOME MEASURES

n1-p1 amplitudes values, interaural amplitude asymmetry ratios (ARs) and response rates.

RESULTS

The belly-tendon electrode montage (BTEM) produced larger amplitudes than the chin ( p = 0.008) and the IOEM (infra-orbital electrode montage; p < 0.001). The chin montage displayed larger amplitudes than the IOEM ( p < 0.001). The interaural amplitude asymmetry ratios (ARs) were not affected by the different electrode montages ( p = 0.549). In 100% of cases, oVEMPs were detected bilaterally with the BTEM which is higher than with the chin and the IOEM ( p < 0.001; p = 0.020, respectively). We did not record any VEMP when placing the active electrode on the contralateral internal canthus or the chin and the reference electrode on the dorsum of the hand.

CONCLUSIONS

The BTEM increased the amplitudes recorded and response rate in healthy subjects. No positive or negative reference contamination was observed with the belly-tendon or chin montages.

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.

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.

[Evidence-based diagnostic use of VEMPs : From neurophysiological principles to clinical application. German version]

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 of an 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 neuronal projections of the utricle and the saccule. 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.

Vestibular evoked myogenic potentials in practice: Methods, pitfalls and clinical applications

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Vestibular evoked myogenic potentials (VEMPs) are used to test the otolith organs in patients with vertigo and imbalance.

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This review discusses the optimal procedures for recording VEMPs and the pitfalls commonly encountered by clinicians.

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Better understanding of VEMP methodology should lead to improved quality of recordings.

Vestibular evoked myogenic potentials (VEMPs) are a useful and increasingly popular component of the neuro-otology test battery. These otolith-dependent reflexes are produced by stimulating the ears with air-conducted sound or skull vibration and recorded from surface electrodes placed over the neck (cervical VEMPs) and eye muscles (ocular VEMPs). VEMP abnormalities have been reported in various diseases of the ear and vestibular system, and VEMPs have a clear role in the diagnosis of superior semicircular canal dehiscence. However there is significant variability in the methods used to stimulate the otoliths and record the reflexes. This review discusses VEMP methodology and provides a detailed theoretical background for the techniques that are typically used. The review also outlines the common pitfalls in VEMP recording and the clinical applications of VEMPs.

Ocular Vestibular Evoked Myogenic Potentials: Where Are We Now?

OBJECTIVE

Over the last decade, ocular vestibular evoked myogenic potentials (oVEMPs) have evolved as a new clinical test for dynamic otolith (predominantly utricular) function. The aim of this review is to give an update on the neurophysiological foundations of oVEMPs and their implications for recording and interpreting oVEMP responses in clinical practice.

CONCLUSION

Different lines of anatomical, neurophysiological, and clinical evidence support the notion that oVEMPs measure predominantly contralateral utricular function, while cervical cVEMPs are an indicator of ipsilateral saccular function. Bone-conducted vibration (BCV) in the midline of the forehead at the hairline (Fz) or unilateral air-conducted sound (ACS) are commonly used as stimuli for oVEMPs. It is recommended to apply short stimuli with short rise times for obtaining optimal oVEMP responses. Finally, this review summarizes the clinical application and interpretation of oVEMPs, particularly for vestibular neuritis, Ménière's disease, superior canal dehiscence and "challenging" patients.

Neuro-otology- some recent clinical advances

Vestibular disorders manifesting as vertigo, chronic dizziness and imbalance are common problems in neurological practice. Here, we review some recent interesting and important advances in diagnosis of vestibular disorders using the video head impulse test and in the management of benign positional vertigo and migrainous vertigo.