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

Masseter Vestibular evoked myogenic potentials: A new tool to assess the vestibulomasseteric reflex pathway

Purpose

This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials (mVEMP). The article also reviews the contemporary researches involving the clinical applications of the mVEMP.

Conclusions

Masseter VEMP is an evolving yet clinically promising neuro-otology test tool that has recently gained more research interest and is considered an additional tool to diagnose various vestibular disorders. Masseter VEMP assesses the functional integrity of the acoustic-masseteric and vestibulo-masseteric reflex pathways. The mVEMP could be used as a complementary test to evaluate the same peripheral generator as the cervical VEMP but a different central pathway i.e., vestibulo-trigeminal pathway. Various research studies that have experimented on parameters such as the effect of different electrode montages (zygomatic vs mandibular configurations), stimulation rates, filter settings and stimuli used to evoke mVEMP have been discussed in this article that could assist in the optimization of a comprehensive clinical protocol. The latency and the amplitude of mVEMP waveforms serve as significant parameters in differentiating normals from those of the clinical populations. Along with the cVEMPs and oVEMPs, mVEMP might help diagnose brainstem lesions in REM Sleep behaviour disorders, Multiple Sclerosis and Parkinson's disease. However, further studies are required to probe in this area of research.

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.

Comparison of Chirp Versus Tone Burst- and Click-Evoked Masseteric Vestibular Evoked Myogenic Potentials in Normal-Hearing Adults

PURPOSE

This study aimed at comparing narrowband Claus Elberling level-specific chirp (NB CE-Chirp)-, click-, and tone burst-evoked masseteric vestibular evoked myogenic potentials (mVEMPs).

METHOD

Within-group study design and purposive sampling were performed. A total of 25 normal-hearing individuals participated in the study. The zygomatic electrode montage was used to elicit ipsilateral mVEMP responses using a 500-Hz NB CE-Chirp, a click of 100-μs duration, and a 500-Hz tone burst stimulus. Each of the responses was analyzed based on the absolute peak latency of P11 and N21, the electromyography-scaled peak-to-peak amplitude of the P11-N21 complex, and the interaural asymmetry ratio.

RESULTS

A total of 50 ears were tested and had 100% mVEMP responses. The latencies of click-evoked and 500-Hz NB CE-Chirp-evoked mVEMPs were significantly shorter than those of 500-Hz tone burst-evoked mVEMPs (p < .05) for both ears. It revealed a significantly superior P11-N21 amplitude of the 500-Hz NB CE-Chirp and tone burst than clicks for both ears. Intraclass correlation coefficient revealed moderate to excellent test-retest reliability for mVEMP parameters across three different stimulations.

CONCLUSION

The present study supports 500 Hz NB CE-Chirps as effective and reliable stimuli as tone bursts in eliciting mVEMP responses.

Comparison of Compressed High-Intensity Radar Pulse and Tone Burst Stimulation in Vestibular Evoked Myogenic Potentials in Acute Peripheral Vestibular System Pathologies

BACKGROUND

It is ascertained that the compressed high-intensity radar pulse (CHIRP) is an effective stimulus in auditory electrophysiology. This study aims to investigate whether Narrow Band Level Specific Claus Elberling Compressed High-Intensity Radar Pulse (NB LS CE-CHIRP) stimulus is an effective stimulus in the vestibular evoked myogenic potentials test.

METHODS

A case-control study was designed. Fifty-four healthy participants with no vertigo complaints and 50 patients diagnosed with acute peripheral vestibular pathology were enrolled in this study. Cervical and ocular vestibular evoked myogenic potential tests (cervical vestibular evoked myogenic potentials and ocular vestibular evoked myogenic potentials) with 500 Hz tone burst and 500 Hz Narrow Band Level Specific CE-CHIRP stimulations were performed on all participants. In addition, cervical vestibular evoked myogenic potentials and ocular vestibular evoked myogenic potentials tests with 1000 Hz tone burst and 1000 Hz Narrow Band Level Specific CE-CHIRP were performed on 24 Meniere's disease patients. P1 latency, N1 latency, amplitude, threshold, and the asymmetry ratio of responses were recorded.

RESULTS

In healthy participants, with CHIRP stimulus, shorter P1 latency (P < .001), shorter N1 latency (P < .001), and lower threshold (P = .003) were obtained in the cervical vestibular evoked myogenic potentials test; shorter P1 latency (P < .001), shorter N1 latency (P < .001), higher amplitude (P < .001), and lower threshold (P < .001) were obtained in ocular vestibular evoked myogenic potentials test. In symptomatic ears of patients, with CHIRP stimulus, shorter P1 latency (P < .001), shorter N1 latency (P < .001), and lower threshold (P=.013 in cervical vestibular evoked myogenic potentials; P=.015 in ocular vestibular evoked myogenic potentials) were obtained in cervical vestibular evoked myogenic potentials and ocular vestibular evoked myogenic potentials tests. In asymptomatic ears of patients, with CHIRP stimulus, shorter P1 latency (P < .001) and shorter N1 latency (P < .001) were obtained in the cervical vestibular evoked myogenic potentials test; shorter P1 latency (P < .001), shorter N1 latency (P < .001), higher amplitude (P < .001), and lower threshold (P=.006) were obtained in ocular vestibular evoked myogenic potentials test.

CONCLUSION

Our results suggest that due to higher response rates, shorter latencies, higher amplitude, and lower threshold values, the Narrow Band Level Specific CE-CHIRP stimulus is an effective stimulus for both cervical vestibular evoked myogenic potentials and ocular vestibular evoked myogenic potentials tests.

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.