Intraoperative Test/Retest-Variabilität der eCAP-Schwellen in verschiedenen Cochlea-Implantat-Trägern

Introduction: Although the eCAP threshold is a commonly used measure, its test/retest variability has not been documented for various cochlear implant systems. The objective of our study is to evaluate the telemetry of the different systems as an objective method and to determine its variance.

Methods: 55 subjects received a cochlear implant. 21 patients were implanted with a device from ADVANCE BIONICS, 19 participants received a device from MEDEL and 15 individuals obtained an implant from COCHLEAR. The eCAP-thresholds were measured three times for each electrode contact. The coefficient of variation (CV) was calculated first with the three measures of each electrode contact, then for the whole array and at last for all of the implanted electrodes from each manufacturer.

Results: The coefficient of variation for the AB-group was 14,89% (SD 16,22%). For the MEDEL-cohort, the CV was 14,20% (SD 10%), and for the COCHLEAR-set, it was 4,23% (SD 9,46%).

Discussion:This is the first study that has evaluated the test-retest reliability of the neural response using the different programs provided by the companies. The CV can be interpreted as follows: low CV (0% - 10%), moderate CV (10% - 20%), and high CV (greater than 20%). 13 patients out of the 55 (7,15%) were documented as outliers, as the coefficient of variation of them was greater than 20%. Since each company has its own software and algorithms, a direct comparison between the different electrodes was not possible.

Conclusion:This study helps assess the consistency and reliability of the eCAPs. All the manufacturers had a certain degree of variance, but further investigation into factors affecting its variance may be necessary.

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