|Beitragstitel||Towards a Better Understanding of Electrocochleography: Analysis of Real-time Recordings|
Objectives. Real-time electrocochleography (ECochG) has been used as a monitoring tool during cochlear implantation (CI), whereby, amplitude drops have been correlated with postoperative acoustic hearing results. However, no consensus has been reached as to how a single event of an amplitude drop should be characterized. The aim of this study was to determine the effects of ECochG events that predict a 25% relative loss of hearing 1 month after surgery.
Design. Fifty-five patients were included in this prospective cohort study. Real-time ECochG measurements were performed during CI electrode insertion. Single ECochG events were characterized according to their amplitude loss and slope steepness. The most efficient cut-off criterion of the ROC analysis defined the threshold of an ECochG event. Applying this definition, the number of events, the extent of amplitude loss, and the recovery rate were collected and correlated to surgical experience and acoustic hearing outcomes.
Results. The most efficient cut-off criterion was an amplitude loss of 61% of the instantaneous signal. Three-quarters of our population had at least one such event during implantation. Most drops occurred shortly before full insertion. With increasing number of drops, median residual hearing thresholds deteriorated for all frequencies. Larger amplitude drops trended towards worse hearing preservation. Signal recovery after an ECochG event could not be correlated to acoustic hearing outcomes.
Conclusions. Our data suggests that amplitude drops exceeding 61% of the ongoing signal are correlated with worse acoustic hearing preservation. Clearly defined ECochG events have the potential to guide surgeons during CI in the future. This is essential if a fully automated data analysis is to be employed, or benchmarking undertaken.