Does the location of electrode on tympanic membrane matter when recording electrocochleography?

The Narrowband CE-Chirp Stimulus Does Not Necessarily Produce More Robust Cervical Vestibular Evoked Myogenic Potential

OBJECTIVE

Various studies have been conducted to search for the most optimal stimulus for eliciting cervical vestibular evoked myogenic potential (cVEMP). More recently, there is a growing interest to study the usefulness of chirp stimuli in cVEMP recording. Nevertheless, contradictory outcomes have been reported across the studies, and further research with larger samples would be beneficial to provide better insight into this matter. As such, the present study was carried out to compare cVEMP results between narrowband (NB) CE-Chirp (centered at 500 Hz) and 500 Hz tone burst stimuli.

DESIGN

In this study that employed a comparative study design, 98 normally hearing adults aged between 19 and 24 years were enrolled. All of them underwent the cVEMP testing based on the recommended test protocol. The stimuli were a 500 Hz tone burst and a NB CE-Chirp (360-720 Hz) presented through insert earphones at an intensity level of 120.5 dB peSPL.

RESULTS

For each stimulus, cVEMP results did not differ significantly between the ears (p > 0.05). Relative to the 500 Hz tone burst, the NB CE-Chirp stimulus produced statistically shorter P1 and N1 latencies (p < 0.001). On the other hand, P1-N1 amplitude was found to be comparable between the two stimuli (p > 0.05).

CONCLUSIONS

The present study did not find any supporting evidence that the NB CE-Chirp stimulus (centered at 500 Hz) outperformed the conventional 500 Hz tone burst in the cVEMP testing. Both stimuli are considered equally appropriate to record cVEMP responses in clinical settings.

Objective Detection of Tinnitus Based on Electrophysiology

Tinnitus, a common disease in the clinic, is associated with persistent pain and high costs to society. Several aspects of tinnitus, such as the pathophysiology mechanism, effective treatment, objective detection, etc., have not been elucidated. Any change in the auditory pathway can lead to tinnitus. At present, there is no clear and unified mechanism to explain tinnitus, and the hypotheses regarding its mechanism include auditory plasticity theory, cortical reorganization theory, dorsal cochlear nucleus hypothesis, etc. Current theories on the mechanism of tinnitus mainly focus on the abnormal activity of the central nervous system. Unfortunately, there is currently a lack of objective diagnostic methods for tinnitus. Developing a method that can detect tinnitus objectively is crucial, only in this way can we identify whether the patient really suffers from tinnitus in the case of cognitive impairment or medical disputes and the therapeutic effect of tinnitus. Electrophysiological investigations have prompted the development of an objective detection of tinnitus by potentials recorded in the auditory pathway. However, there is no objective indicator with sufficient sensitivity and specificity to diagnose tinnitus at present. Based on recent findings of studies with various methods, possible electrophysiological approaches to detect the presence of tinnitus have been summarized. We analyze the change of neural activity throughout the auditory pathway in tinnitus subjects and in patients with tinnitus of varying severity to find available parameters in these methods, which is helpful to further explore the feasibility of using electrophysiological methods for the objective detection of tinnitus.