Can we use electrocochleography as a clinical tool in the diagnosis of Meniere's disease during the early symptomatic period?

Functional and Molecular Markers for Hearing Loss and Vertigo Attacks in Meniere's Disease

Meniere's disease (MD) is one of the most complicated diseases in the otologic clinic. The complexity of MD is partially due to the multifactorial etiological mechanisms and the heterogenous symptoms, including episodic vertigo, hearing loss, aural fullness and tinnitus. As a result, the diagnosis of MD and differentiating MD from other diseases with similar symptoms, such as vestibular migraine (VM), is challenging. In addition, it is difficult to predict the progression of hearing loss and the frequency of vertigo attacks. Detailed studies have revealed that functional markers, such as pure tone audiometry (PTA), electrocochleography (ECochG), vestibular evoked myogenic potential (VEMP), caloric test, video head impulse test (vHIT) and magnetic resonance imaging (MRI) could help to evaluate MD with different hearing levels and frequency of vertigo attacks. Investigations of molecular markers such as autoimmunity, inflammation, protein signatures, vasopressin and circadian clock genes in MD are still underway. This review will summarize these functional and molecular markers, address how these markers are associated with hearing loss and vertigo attacks in MD, and analyze the results of the markers between MD and VM.

The Correlation of a 2D Volume-Referencing Endolymphatic-Hydrops Grading System With Extra-Tympanic Electrocochleography in Patients With Definite Ménière's Disease

Background: Although magnetic resonance imaging (MRI) of the membranous labyrinth and electrocochleography (ECochG) have been used to diagnose endolymphatic hydrops (ELH) in patients with Ménière's disease (MD), the relationship between imaging and ECochG is not well-documented. Objectives: This study evaluates the ELH using 3D-FLAIR MRI and extra-tympanic ECochG (ET-ECochG) and correlates the results from 3D-FLAIR MRI to those from ET-ECochG. Materials and Methods: 3D-FLAIR MRI images of 50 patients were assessed using a 2D volume-referencing grading system (VR scores, relative scores according to the known volumes of the cochlea, vestibule, and semicircular canals). Forty healthy subjects were included and compared to 51 definite MD ears of 50 patients while analyzing the ET-ECochG, which used a self-made bronze foil electrode. The amplitude ratio of the summating potential (SP) to the action potential (AP) (SP/AP) and the area ratio of SP to AP (Asp/Aap) were collected. Relative ELH grade scores were then correlated to ET-ECochG (SP/AP, Asp/Aap). Results: The VR scores showed a better correlation (r = 0.88) with the pure tone average (PTA), disease duration, and vertigo frequency of MD than the Bernaerts scores (grading the cochlea and vestibule separately) (r = 0.22). The SP/AP and Asp/Aap of the unilateral MD patients were statistically comparable to those measured in contralateral ears and the results between the definite MD ears with healthy ears were statistically comparable (p < 0.05). In a ROC analysis Asp/Aap (area under curve, AUC 0.98) significantly (p = 0.01) outperformed SP/AP (AUC 0.91). The total score of ELH, vestibular ELH, and cochlear ELH were also correlated with SP/AP and Asp/Aap. The strongest correlation was found between the Asp/Aap and cochlear ELH (r = 0.60). Conclusion: The 2D volume-referencing grading system was more meaningful than the Bernaerts scores. A correlation was found between ELH revealed by 3D-FLAIR MRI and the SP/AP of ET-ECochG in evaluating definite MD patients. The Asp/Aap appeared a more sensitive and reliable parameter than SP/AP for diagnosing the ELH of the membranous labyrinth.

Electrocochleography: New Uses for an Old Test and Normative Values

Purpose This article combines the results of 3 studies that were presented at the HeAL 2018 Conference in Lake Como, Italy, in June 2018. Each study involved electrocochleography (ECochG), a neurodiagnostic evaluation that has been used clinically for over 80 years but whose applications continue to expand. The 1st study describes recent research wherein ECochG was recorded from asymptomatic subjects who were siblings or offspring of patients with a confirmed diagnosis of Ménière's disease (MD). Our results provide evidence that ECochG may be helpful in not only diagnosing MD but also predicting it as well. Second, case studies are described where ECochG was important in both diagnosing superior semicircular canal dehiscence and monitoring the repair of this condition during surgery. Finally, although ECochG has been practiced clinically for over 8 decades, the protocols for recording, measuring, and interpreting the electrocochleogram continue to lack standardization among clinicians and scientists. We thus present normative data for some of these features based on noninvasive recordings made from the tympanic membrane from 100 normal hearing subjects. Conclusions Although the primary use of ECochG continues to be in the diagnosis of MD, we report on 2 additional clinical applications for this important test of inner ear/auditory nerve function. First, a preliminary study on a small sample of subjects indicates that ECochG may also be useful in predicting MD prior to the onset of symptoms in individuals who may be genetically predisposed to developing it. Second, through a series of case studies, we demonstrate how ECochG is used to help diagnose superior semicircular canal dehiscence and monitor the status of the inner ear during the surgical repair of this condition. Finally, normative values for clinically important components of the electrocochleogram based on tympanic membrane recordings have been established from a large sample of subjects.

A systematic review and meta-analysis of extratympanic electrocochleography in Ménière's disease diagnosis

Objective: Determine whether a combination of electrocochleography determined summating/action potential (SP/AP) ratio and other audiological measurements has greater sensitivity and specificity than that achieved with electrocochleography SP/AP ratio alone in diagnosing definite Ménière's Disease. Design: Systematic review and meta-analysis. Study sample: Pubmed, Cochrane Library, and Web of Science were searched using search terms "electrocochleography", "ECochG, ,"ECoG", "Ménière's Disease", and "Idiopathic Endolymphatic Hydrops". Inclusion criteria were extratympanic electrocochleography methodology, English language publication between January 2002 and December 2017, and the 1995 American Academy of Otolaryngology and Head and Neck Surgery Ménière's disease diagnostic criteria. Five articles satisfied inclusion criteria and were sufficiently detailed for aggregate quantitative analysis of SP/AP ratio (315 subjects) and combination audiological measures (113 subjects). Results: The diagnostic sensitivity and specificity of the SP/AP amplitude ratio was 47.6% and 83.8% and of combination diagnostic measures 63.5% and 89.3%, respectively. Point estimates of sensitivity (p = 0.248) and specificity (p = 0.969) and the summary Receiver Operator Characteristic Curve (p = 0.407) were not statistically significant. Conclusion: Statistically, combination diagnostic measures do not result in greater accuracy of definite Ménière's disease diagnosis compared to the SP/AP amplitude ratio alone. However, given the small sample size further studies are recommended to arrive at a definitive conclusion.

Cochlea and auditory nerve

The transduction process in the cochlea requires patent hair cells. Population responses that reflect this patency are the cochlear microphonic (CM) and summating potential (SP). They can be measured using electrocochleography (ECochG). The CM reflects the sound waveform in the form of outer hair cell (OHC) depolarization and hyperpolarization, and the SP reflects the average voltage difference of the OHC membrane potential for depolarization and hyperpolarization. The CM can be measured using ECochG or via the so-called otoacoustic emissions, using a sensitive microphone in the ear canal. Neural population responses are called the compound action potentials (CAPs), which by frequency selective masking can be decomposed into narrow-band action potentials (NAPs) reflecting CAPs evoked by activity from small cochlear regions. Presence of CM and absence of CAPs are the diagnostic hallmarks of auditory neuropathy. Increased and prolonged SPs are often found in Ménière's disease but are too often in the normal range to be diagnostic. When including NAP waveforms, Ménière's disease can be differentiated from vestibular schwannomas, which often feature overlapping symptoms such as dizziness, hearing loss, and tinnitus. The patency of the efferent system, particularly the olivocochlear bundle, can be tested using the suppressive effect of contralateral stimulation on the otoacoustic emission amplitude.

Normative data for TM electrocochleography measures

Objective

Establish normative data for tympanic electrocochleography (TM ECochG) parameters in normal hearing adults without Ménière's disease's (MD) symptoms. Describe TM ECochG variables that help to distinguish normal from MD ears.

Material and methods

We enrolled 100 subjects (N = 200 ears), 59 females, aged between 19 and 71 years from 09/2010 to 04/2014. Inclusion criteria: normal otomicroscopy, hearing thresholds ≤25 dB nHL from 250 to 4000 Hz, normal tympanogram, no symptoms of MD according to the AAO-HNS 1995 criteria and Gibson's score <7. We excluded subjects with dizziness, aural fullness or other symptoms of endolymphatic hydrops. The following parameters were analyzed: SP/AP amplitude ratio, SP/AP area ratio and the difference between AP latency with rarefaction and condensation stimuli.

Results

There was no significant difference between right and left ears (Intraclass correlation coefficient < 0.6). SP/AP amplitude ratio varied between 0.084 and 0.356 and SP/AP area ratio between 0.837 and 1.671 (percentiles 5 and 95). The AP latency difference to rarefaction and condensation clicks was between 0.0 and 0.333 ms.

Conclusion

Normative data for TM ECochG parameters were established in 100 normal hearing subjects without MD. These data can be used to distinguish normal from pathological findings and in follow-up of MD patients.

Characteristics of the Cochlear Symptoms and Functions in Meniere's Disease

BACKGROUND

Meniere's disease is a unique, progressive disease of the inner ear. The complex manifestation presents diagnostic challenges. The cochlear symptoms often present before vertigo and tend to be ignored. This study aimed to analyze the characteristics of cochlear symptoms and functions associated with Meniere's disease to investigate the regularity of the development of this disorder.

METHODS

One-hundred fifteen patients who were diagnosed with definite unilateral Meniere's disease at the Hearing and Vestibular Clinic of the Department of Otorhinolaryngology of Beijing Tongren Hospital from August 2013 to November 2015 were recruited in this retrospective study. Initial symptoms, duration from initial symptoms to the diagnosis, hearing thresholds, audiogram patterns, and caloric test results were collected and analyzed for each patient. Data were analyzed using SPSS 13.0 statistical software by Spearman's correlation, Kruskal-Wallis H test, Chi-square test, and Fisher's exact test.

RESULTS

The average hearing threshold of these patients was 45.24 ± 18.40 dB HL. A majority of the patients (55.65%) were in Stage 3. The initial presentation of the disorder in 58 cases (50.43%) comprised only cochlear symptoms without vertigo. A weak, positive correlation was found between the degree of hearing loss and duration of the disease from initial symptoms to the diagnosis (rs = 0.288, P = 0.002). Upward-sloping, inverted "V," downward-sloping, and flat pattern were the main audiometric patterns observed with a distinctive distribution between stages (P < 0.001). Based on the configurations of audiograms, the audiometric patterns had a weak correlation to the duration (rs = 0.269, P = 0.004), and there was a tendency of duration to rising from upward-sloping, inverted "V", downward-sloping to flat pattern. (H = 10.024, P = 0.018). Frequencies of tinnitus in 56 patients (64.4%) were at the lowest points of the audiograms, i.e., the frequencies of the poorest hearing threshold. The patients at an advanced stage (Stage 3 [56] and Stage 4 [73]) exhibited a significantly higher abnormality of canal paresis than those at the earlier stages (Stage 1 [23] and Stage 2 [42]) (χ2 = 5.973, P = 0.015).

CONCLUSIONS

Patients with definite Meniere's disease always have a moderate to severe sensorineural hearing loss before diagnosis. Cochlear symptoms are the most common initial presentation. With the progression of the duration, the hearing impairment becomes more severe and the distribution of the audiometric pattern is distinctive between stages.

Ups and Downs in 75 Years of Electrocochleography

Before 1964, electrocochleography (ECochG) was a surgical procedure carried out in the operating theatre. Currently, the newest application is also an intra-operative one, often carried out in conjunction with cochlear implant surgery. Starting in 1967, the recording methods became either minimal- or not-invasive, i.e., trans-tympanic (TT) or extra tympanic (ET), and included extensive studies of the arguments pro and con. I will review several valuable applications of ECochG, from a historical point of view, but covering all 75 years if applicable. The main topics will be: (1) comparing human and animal cochlear electrophysiology; (2) the use in objective audiometry involving tone pip stimulation-currently mostly pre cochlear implantation but otherwise replaced by auditory brainstem response (ABR) recordings; (3) attempts to diagnose Ménière's disease and the role of the summating potential (SP); (4) early use in diagnosing vestibular schwannomas-now taken over by ABR screening and MRI confirmation; (5) relating human electrophysiology to the effects of genes as in auditory neuropathy; and (6) intracochlear recording using the cochlear implant electrodes. The last two applications are the most recently added ones. The "historical aspects" of this review article will highlight the founding years prior to 1980 when relevant. A survey of articles on Pubmed shows several ups and downs in the clinical interest as reflected in the publication counts over the last 75 years.

Validity and Reliability of the Diagnostic Tests for Ménière's Disease

Ménière's disease is defined as an idiopathic syndrome characterized by endolymphatic hydrops. Various tests and measurement methods have been employed for the diagnosis of Ménière's disease. These include audiological, vestibular, radiological, clinical, and biochemical tests. However, the lack of a definitive or gold standard diagnostic test sometimes complicates the process of diagnosis. Hence, the clinician should be well-experienced in deciding when to perform a test and how to interpret the results of the test. Furthermore, having the knowledge of the validity and reliability of these tests plays a critical role. This review particularly emphasizes on remarking the validity and reliability of each test performed for the diagnosis of Ménière's disease and discussing the results according to the up-to-date literature.

Extra-tympanic electrocochleography in a normal population. A descriptive study

INTRODUCTION AND OBJECTIVES

Extra-tympanic electrocochleography is an electrophysiological register obtained after stimulating the cochlea with an audible stimulus. This stimulus is applied using an earphone over the external auditory canal, while the electrical activity is registered by surface electrodes. There are few studies that analyse normal electrocochleography in our environment. Thus, the main objective of our study was to regularize the values obtained with electrocochleography in ears without any otoneurological diseases. We explain in detail the process of obtaining the register.

METHODS

Sixty healthy ears were studied by extratympanic electrocochleography. Statistical results were analysed. While 30 ears were studied with a stimulus at 90dB, another 30 ears were studied with a stimulus at 80dB.

RESULTS

Summating potential and action potential latencies and amplitudes were measured. Summating potential/action potential ratios were calculated. Wave I and wave II latencies were also determined. These results were analysed in function of stimulus intensity, patient gender, patient age group and ear side studied.

CONCLUSIONS

This study collected extra-tympanic electrocochleography data in a normal population and the results were in the range of other international studies obtained in other countries. These data can be used as a reference to evaluate illnesses that affect cochlear structure or functions.