Intertest Reliability in Non-invasive Electrocochleography

Abstract

Intertest reliability of action potential (AP) and summating potential (SP) parameters in non-invasive electrocochleography (ECochG) was studied in 4 normal ears and 7 hearing-impaired ears with stable audiograms. The interval between test and retest was 10 days to 2 years and 5 months. Intertest differences in AP response threshold and -SP detection threshold were within 10 dB. N₁ amplitude, N₁ latency, -SP amplitude, and -SP/AP ratio had excellent correlations between test and retest. N₁ latency had a better intertest reliability than N₁ amplitude. Waveform had almost the same shape in retest as in test. The intertest differences in AP and SP parameters were examined. On the basis of these data values for the criteria of significant change in test and retest in non-invasive ECochG are presented. The non-invasive ECochG is particularly suitable for monitoring both progressive and fluctuant hearing loss.

Nous avons cherché quelle pouvait ětre la valeur test-retest de l'ECochG extra-tympanique (paramètres du PA et du PS) sur 4 oreilles normales et 7 oreilles atteintes de surdité avec audiogramme stable, l'intervalle entre les tests allant de 10 jours à 29 mois. Nous avons pu observer éntre les tests: un ecart inférieur a 10 dB concernant les seuils, une excellente corrélation entre les amplitudes de N₁; surtout entre les latences de N₁, aussi entre les amplitudes de -PS, ainsi qu'une très bonne similitude des formes des réponses. Devant ces observations nous pensons que l'ECochG extra-tympanique est une technique tout à fait valable pour surveiller une surditd progressive ou fluctuante.

Key Words:

• Non-Invasive electrocochleography
• Intertest reliability
• Action potential
• Summating potential
• Waveform