ESRT as a Predictor in Fine Structure Audio Coding Strategy and Variable Pulse Duration in CI Fitting

Objectives

The introduction of new charge-based coding strategies, like FSP, requires correlations for the change in charge in order to assess the clinical relevance of the eSR threshold measurements.

The aims of the study was to compare the eSR thresholds recorded using charge units in experienced adults fitted with Med-El cochlear implants with the MCLs obtained for the apical, medial and basal electrodes.

Material and Method

30 experienced patients participated in the preliminary part of the study. All of them used Med-El implants and were fitted using Maestro 7 or earlier.

The MCLs were set on all active electrodes. Then eSR measurements were obtained on basal, medial and apical electrodes (electrodes 2, 6 and 11). After successfully finished preliminary stage, we enlarge study group to more than 500 CI users, fulfilled the same criteria.

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Results

The eSR thresholds and MCLs were obtained successfully in every participant in preliminary group, and in majority of patients in enlarged group.

In the preliminary group the mean eSR threshold was 92.7% of the mean MCL for all electrodes combined. The mean eSR thresholds for the electrodes tested varied from 88.2% (electrode 6) to 95.1% (electrode 2) of the MCL. The correlations between the eSR threshold and MCL measured for each electrode varied from 0.8 to 0.83.

Further study in bigger group confirmed described values.

Conclusions

ESR thresholds, recorded in units of charge on experienced patients implanted with Med-El cochlear implants, have been correlated with MCL values obtained using apical, medial and basal electrodes.