Normative data for TM electrocochleography measures

Objective: Establish normative data for tympanic electrocochleography(TM ECoch G) parameters in normal hearing adults without Meniere's disease's(MD) symptoms. Describe TM ECoch G 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 ECoch G 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.

Comparison of Transtympanic and Extratympanic Electrocochleography

Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere’s disease or endolymphatic hydrops. There are two methods employed, transtympanic and extratympanic. Many have regarded the results of these methods as being equally reliable. The purpose of this study is to determine any differences in sensitivity between the two methods. In this study patients with known endolymphatic hydrops or Meniere’s disease underwent ECoG testing with both the extratympanic method and the transtympanic method on the same day in the same ear. The results show a significant difference between the two methods, with the transtympanic wave values being smaller and therefore more sensitive than the extratympanic method. In addition, transtympanic ECoG resulted in better waveform morphology and better correlation with the audiometric findings in endolymphatic hydrops and Meniere’s disease. The results emphasize the superior role of transtympanic ECoG over extratympanic ECoG as a valuable component in the confirmation of Meniere’s disease or endolymphatic hydrops along with history and audiometric findings characteristic of the disease. Implications of the study promote the use of transtympanic ECoG rather than extratympanic ECoG in patients with symptoms suggestive of Meniere’s disease or endolymphatic hydrops.

Application of intraoperative round window electrocochleography for screening the patients with auditory neuropathy

Background Most patients with auditory neuropathy （AN） could receive good even the best effects after cochlear implantation. How to diagnose AN objectively and accurately is very important. In this study, we screened the patients with AN according to the presence or absence of compound action potential （CAP） of intraoperative round window electrocochleography （RW ECochG）. Methods Intraoperative RW ECochG was performed on 32 patients with profound sensorineural deafness, who had normal cochlea during cochlear implantation surgery under general anesthesia in the standard operating room. The cochlear microphonic （CM） and CAP of RW ECochG was observed and recorded. Results The presence of CM but the absence of CAP of RW ECochG occurred in 12 among the 32 patients. They were suspected to suffer from AN. The rest patients who had CM and CAP of RW ECochG were thought not to suffer from AN. Conclusion Application of intraoperative RW ECochG during the cochlear implantation surgery may objectively and accurately screen the patients with AN, and can give a meaningful clue for implanted device working.

Electrocochleographic recording in Asian adults: Preliminary normative data and demographic analyses

Objective: Electrocochleography(ECochG) is valuable to diagnose Meniere's disease objectively. The aim of the present study was to provide preliminary normative data for ECochG among Asian adults. The influences of ethnicity(Malay versus Chinese) and gender on ECoch G results were also studied.Methods: Twenty-two Malay adults(10 men and 12 women) and twenty Chinese participants(10 men and 10 women) aged between 20 and 49 years participated in this study. Extratympanic ECoch G(ET-ECochG) was recorded according to standard non-invasive procedure. Summating potential(SP) amplitude, action potential(AP) amplitude and SP/AP ratio were analyzed accordingly.Results: ET-ECoch G results were found to be comparable between left and right ears(p > 0.05). No notable differences in ET-ECochG results were found between Malay and Chinese groups(p > 0.05). No significant influence of gender on ET-ECochG outcomes was also noted(p > 0.05). The derived normative data for Asian adults(84 ears) are consistent with previous reports.Conclusion: The present study provides preliminary normative data for ET-ECochG among Asian adults. The ECoch G components do not appear to be influenced by either ethnicity or gender. The derived normative data can be used for clinical applications and as the reference for future studies involving Asian population.

Is Meniere Disease Caused by a Pathological Immune Response?

The etiology of Meniere disease (MD) is unknown. Among the several factors which can provoke the disease is a pathological immune response. Objective: To investigate whether MD is due to a pathological immune reaction. Materials and methods: Immunological assay (IA) was evaluated in a consecutive study on 159 patients with MD (mean age 47.8. years) and the results compared with those from 26 patients operated on because of vestibular schwannoma (VS, mean age 54.1 years), who served as a control group. In cases of MD, transtympanic electrocochleography (ECoG) and hearing threshold were measured. Results: The average hearing level (HL) in the affected ears of patients with MD was 30 dB. Evidence of abnormal plasma protein pattern was found in 127 MD patients (80%). Elevations were found in β1-globulin (54.5%), β2-globulin (26.5%), a2-globulin (34.3%), g-globulin (17.3%), complement (CH100, 36.4%) and antinuclear antibodies (ANA, 43.4%). The onset of the disease did not correlate with the level of the plasma protein neither with the level of IgG titers. Conclusion: Elevated certain plasma proteins in patients with Meniere’s disease could be a sign that Meniere’s disease is a consequence of pathological immune reaction.

Identification of early-stage Meniere’s disease as a cause of unilateral tinnitus

Introduction:Meniere’s disease(MD)is characterized by episodic symptoms,including vertigo,hearing loss,and tinnitus.Objectives:in this study,cases of unilateral tinnitus were investigated for MD.Method:Twenty-two patients who presented with chronic unilateral tinnitus on puretone audiograms showing an average threshold better than 25 dB HL and thresholds in the lower frequencies worse than those in the higher frequencies by more than 10 dB were suspected to have early-stage MD and underwent electrocochleography(ECochG).Patients showing ECochG findings conclusive for MD were compared to a control group of patients presenting with chronic unilateral tinnitus on pure-tone audiograms showing an average threshold better than 25 dB and thresholds in the higher frequencies worse than those in the lower frequencies by more than 10 dB.Results:Eighteen of the 22 patients included in this study showed elevated summating potential amplitude to action potential amplitude ratios in ECochG(suggestive of endolymphatic hydrops due to MD)and were followed up for 2 months;14 of them experienced at least two attacks of vertigo or unsteadiness.In contrast,only one patient in the control group reported two or more attacks of vertigo or unsteadiness in the 2 month observation period.The incidence of this finding in the two groups was significantly different.Conclusion:Patients with early-stage MD can present with only unilateral tinnitus.Thus,the addition of“pure-tone audiograms showing lower-frequency thresholds worse than higher-frequency thresholds”to the probable MD category in the globally.