Intrasubject test‐retest variability in clinical electrocochleography

Abstract

Seventeen healthy volunteers without a history of auditory or vestibular difficulty and with normal screening audiometry had bilateral (34 ears) electrocochleography performed repeatedly at 1-week intervals. Each subject had from four to seven electrocochleograms performed on each ear. Measurements were made in the external auditory canal using a gold-foil "TIPtrode." Amplitude and latency for the summating potential (SP) and action potential (AP) were measured and SP/AP ratios were calculated. Averages and standard deviations for amplitude, latency, and SP/AP ratios were computed. The average SP/AP ratio was 0.22 with a standard deviation of 0.06. The range was 0.04 to 0.50. The average difference between the highest and lowest SP/AP ratio for a given individual was 0.155 (i.e., the range 0.03 to 0.31) with a standard deviation of 0.07. These normative data are useful in assessing the results of dehydration electrocochleography and in establishing how much test-retest variation is required to suggest pathology.

The Effect of Test, Electrode, and Rate on Electrocochleography Measures

“…SP amplitude, AP latency, AP amplitude, SP/AP amplitude ratio, and SP/AP area ratio are generally similar to those reported in the literature for extratympanic (Coats, 1981;Oh et al, 2014) and tympanic (Margolis et al, 1992;Ferraro and Tibbils, 1999;Grasel et al, 2017) electrode placements. Variability across measures was also similar for extratympanic (Roland et al, 1993) and tympanic (Park and Ferraro, 1999) electrode placements. Our findings with regard to rate are similar to Wilson and Bowker (2002) in that a slow rate allowed for easily identified ECochG components.…”

“…Park and Ferraro (1999) used a tympanic electrode placement with a custom made tymptrode. There has been only one study evaluating the reliability of the TIPtrodeä electrode (Roland et al, 1993). They evaluated 17 normal hearing adults tested repeatedly over 1-week periods averaging 5.3 weeks.…”

“…Averages and standard deviation (SD) of SP and AP amplitudes were measured and SP/AP amplitude ratios calculated. Roland et al (1993) reported an average SP/AP amplitude ratio of 0.22 with an SD of 0.06. To the best of our knowledge, there are no studies examining the repeatability of the ECochG measures with any commercially available tympanic electrode.…”

Da eletrococleografia transtimpânica em pacientes com e sem hydrops endolinfático e limiares auditivos iguais ou maiores que 50 decibéis

“…8 A eletrococleografia transtimpânica foi o método de exame utilizado nesta pesquisa, por ser consagrada pela literatura como a que permite a obtenção das melhores respostas, com pouca variabilidade intrateste e interteste. 20,21 A escolha da relação SP/AP como principal parâmetro na avaliação dos resultados foi fundamentada na afirmação de Coats que propôs a avaliação desta relação para diminuir a grande variabilidade interindividual das amplitudes de SP e AP 22 . A avaliação das amplitudes dos dois picos que delimitam o N 2 (I/BSL e II/BSL) se baseou na hipótese de que a associação destes parâmetros com a relação SP/AP poderia ajudar na diferenciação entre os grupos, seguindo o conceito de associação de parâmetros bastante utilizado no estabelecimento do diagnóstico clínico da doença 23 .…”

Electrocochleography and Intranasal Allergen Challenge as Investigational Tools in Patients With Inhalant Allergy and Ménière's Disease

“…At our institution, intrasubject test–retest variability studies have demonstrated that this variation must exceed 15% to be significant. 4 In addition, the 15% change is the measure that Arenberg et al 5 chose as an indicator of sufficient shift in the SP/AP ratio to be meaningful for their study on endolymphatic duct surgery.…”