Cervical vestibular evoked myogenic potentials via air conduction delivered by either sequentially or quasi-simultaneously presented narrow-band chirp stimuli

Bone conducted cervical vestibular evoked myogenic potentials: comparison of tone burst stimulus vs chirp stimulus

PURPOSE

Vestibular evoked myogenic potential (VEMP) is a test used to evaluate the function of otolith organs. In healthy individuals, air-conducted (AC) responses are obtained, whereas, in conductive hearing loss, the inability to transmit the signal well enough with AC stimuli has led to the need for bone-conducted (BC) stimuli. This study aimed to compare 500 Hz Chirp and Tone Burst stimuli in terms of latency and amplitude in BC cVEMP.

METHODS

This prospective observational case control study included 35 healthy participants (70 ears) between the age of 20-50. Participants underwent VEMP testing with BC 500 Hz Tone Burst stimulus and 500 Hz narrow band Chirp stimulus without changing the position of the bone conducted vibrator. The intensity of the stimuli was 50 dB nHL.

RESULTS

Response rate of 500 Hz TB Stimulus was 51.4% and 95.7% in Chirp stimulus. It was observed that significantly more responses were obtained with Chirp stimulus than TB stimulus (p < 0.001). In terms of p1 latency, n1 latency, both latencies were significantly shorter in Chirp stimulus (p < 0.001). p1n1 amplitude was found significantly larger in Chirp stimulus (p < 0.001).

CONCLUSION

Compared to 500 Hz TB stimulus, 500 Hz Chirp stimulus results in a higher response rate, larger p1n1 amplitude, and shorter p1 and n1 latency. A higher response rate may provide a more accurate assessment of otolith organs, reducing false negatives due to signal transmission in patients.

Using macular velocity measurements to relate parameters of bone conduction to vestibular compound action potential responses

To examine mechanisms responsible for vestibular afferent sensitivity to transient bone conducted vibration, we performed simultaneous measurements of stimulus-evoked vestibular compound action potentials (vCAPs), utricular macula velocity, and vestibular microphonics (VMs) in anaesthetized guinea pigs. Results provide new insights into the kinematic variables of transient motion responsible for triggering mammalian vCAPs, revealing synchronized vestibular afferent responses are not universally sensitive to linear jerk as previously thought. For short duration stimuli (< 1 ms), the vCAP increases magnitude in close proportion to macular velocity and temporal bone (linear) acceleration, rather than other kinematic elements. For longer duration stimuli, the vCAP magnitude switches from temporal bone acceleration sensitive to linear jerk sensitive while maintaining macular velocity sensitivity. Frequency tuning curves evoked by tone-burst stimuli show vCAPs increase in proportion to onset macular velocity, while VMs increase in proportion to macular displacement across the entire frequency bandwidth tested between 0.1 and 2 kHz. The subset of vestibular afferent neurons responsible for synchronized firing and vCAPs have been shown previously to make calyceal synaptic contacts with type I hair cells in the striolar region of the epithelium and have irregularly spaced inter-spike intervals at rest. Present results provide new insight into mechanical and neural mechanisms underlying synchronized action potentials in these sensitive afferents, with clinical relevance for understanding the activation and tuning of neurons responsible for driving rapid compensatory reflex responses.

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.

Cervical and ocular vestibular evoked myogenic potential: A comparison of narrowband chirp, broadband chirp, tone burst and click stimulation

OBJECTIVES

To compare the response rate and response parameters of cervical and ocular vestibular evoked myogenic potentials (c&oVEMP) elicited by narrowband (NB) and broadband (BB) CE-Chirp, with the more classical tone burst (TB) and click VEMPs.

DESIGN

The response rate, latency, amplitude and asymmetry ratio of c&oVEMPs elicited by 95 dB nHL air conducted (AC) 500 Hz NB CE-chirp, BB CE-chirp, 500 Hz TB and click stimuli were recorded bilaterally.

STUDY SAMPLE

20 male and 38 female participants (19-39 years).

RESULTS

For the cVEMP, the highest response rate was found for NB chirp (100%), followed by TB (91%), BB chirp (87%) and finally click (85%). A similar order was seen for oVEMP with percentages of 100%; 57%, 57%, and 43%. The 500 Hz NB CE-Chirp elicited significantly shorter cVEMP P1 and N1 latencies and significantly larger c&oVEMP amplitudes compared to all other stimuli. BB CE-Chirp elicited significantly shorter c&oVEMP P1 and N1 latencies with smaller amplitudes compared to TB. Asymmetry ratios were not statistically significant for all comparisons.

CONCLUSION

The 500 Hz NB CE-chirp provides the highest response rates, shorter latencies and larger amplitudes, and therefore seem a promising stimulus for reliably measuring c&oVEMPs in clinical practice.

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.

Can Narrow Band Chirp Stimulus Shake the Throne of 500 Hz Tone Burst Stimulus for Cervical Vestibular Myogenic Potentials?

Background and Objectives

The aim of the study was to compare effects of tone-burst (TB) and narrow-band (NB) Claus Elberling (CE)-chirp stimuli on amplitude, latency and interaural asymmetry ratio (IAR) of cervical vestibular evoked myogenic potentials (cVEMP) in healthy individuals.

Subjects and Methods

The study included 50 healthy volunteers. cVEMP procedure was carried out using 500 Hz TB and NB-CE-chirp stimulus (360-720 Hz, up-chirp) in random order. cVEMP were recorded at 100 dB nHL. For each ear and each stimulus, P1 latency, N1 latency and P1N1 amplitude were measured. IAR was also calculated.

Results

Mean age was 26.66±9.48 years. cVEMP’s in response to both TB and NB CE-chirp stimuli were obtained in all subjects. No statistically significant difference in P1 latency, N1 latency, and P1N1 amplitude was found between the right and left ears for both TB and NB CE-chirp stimuli (p>0.05). In both sides, P1 and N1 latencies were significantly shorter in NB CE-chirp stimulation compared to TB stimulation (p=0.000). In both sides, no statistically significant difference was found in P1N1 amplitude between two types of stimuli (p>0.05).

Conclusions

The chirp stimulus produces robust but earlier cVEMP than TB does. This largest series study on NB chirp cVEMP shows that NB chirp is a good and new reliable alternative.

Normative Data of Ocular Vestibular Evoked Myogenic Potentials in Response to Chirp Stimulus

OBJECTIVES

This study aims at comparing the tone-burst (TB) and narrow-band (NB) CE-chirp stimuli in terms of amplitude, latency, and interaural asymmetry ratio (IAR) in ocular vestibular evoked myogenic potentials (oVEMP).

MATERIALS AND METHODS

In this prospective study, we enrolled 60 healthy subjects (27 men, 33 women) with a mean age of 25.83 (range, 18-48) years. Otological examination was normal in all the subjects. The subjects did not have any otological disease. All the subjects underwent oVEMP testing. We used 500 Hz TB stimulus and 500 Hz NB CE-chirp stimulus in random order. oVEMP test was performed at 100 dB normalized hearing level. P1 latency, N1 latency, and P1N1 amplitude were measured for each ear and stimulus, and IAR was calculated.

RESULTS

Ocular VEMPs were obtained from all the subjects for both the stimuli. P1 and N1 latencies were significantly shorter in chirp stimulus than in TB stimulus for both the sides (p<0.0001). P1 and N1 amplitudes were significantly higher for chirp stimulus than for TB stimulus for both the sides (p<0.0001). There was no significant difference between the ears in IAR between the 2 types of stimuli.

CONCLUSION

Narrow-band CE-chirp stimulus is an effective stimulus to evoke oVEMP with higher amplitudes and shortened latencies.