Authors:
Wiebke Konerding (Hannover | DE)
Cornelia Batsoulis (Hannover | DE)
Peter Baumhoff (Hannover | DE)
Heval Benav (Innsbruck | AT)
Lutz Gärtner (Hannover | DE)
Annette Günther (Hannover | DE)
Onhintz de Olano Dietrich (Hannover | DE)
Daniel Schurzig (Hannover | DE)
Stefan Strahl (Innsbruck | AT)
Jochen Tillein (Innsbruck | AT)
Sarah Vormelcher (Hannover | DE)
Andreas Büchner (Hannover | DE)
Carolyn Garnham (Innsbruck | AT)
Andrej Kral (Hannover | DE)
Goals
Previously, we derived an electrophysiological marker for neural health profiles in the animal model (Konerding et al. 2025a). This electrically-evoked compound-action potential (eCAP)-derived Failure Index (FI) was indicating the presence of a mechanically induced, spatially restricted lesion of the spiral ganglion neurons. Thereby, a high FI indicated the failure to effectively transmit current into neural signals and the size of the elevation indicated the presence, site and size of a lesion. Here, we translated the FI to clinical recordings of MED-EL CI users.
Material and Methods
For the retrospective study (Konerding et al. 2025b), we selected patient data from the database of the German Hearing Center Hannover recorded 2017 to 2024. We included 199 post-lingually and 79 pre-lingually deafened ears. The eCAPs were recorded at the Deutsche Hörzentrum Hannover between August 2017 and August 2024. To accommodate for differences in stimulation-phase duration, we calculated the FI as the charge needed to reach saturation level, divided by the eCAP amplitude reached at this maximal charge level. Changes in FI were analysed with regard to factors expected to impact cochlear health, such as age, duration/cause of deafness, and stimulation position (apical to basal). As proxy of cochlear health, we used speech perception in quiet and noise and correlated with eCAP-derived measures.
Results
Averaged FIs over all contacts of a CI were stable within the analysis period (3rd month to 1st year postoperatively). The averaged FI increased with age and was elevated for etiologies associated with higher SGN loss. Utilizing 3D information from cone beam-computed tomography scans, we confirmed that the FI was independent of distance to the modiolus. The FI showed individual patterns along the array with maxima usually at basal contacts, corresponding to reduced cochlear health at high-frequency regions. In a selected group of post-lingually deaf ears, we confirmed significant correlation with speech perception, with higher goodness of fit than for other eCAP measures (i.e., threshold, slope and amplitude).
Conclusion
The results are in line with the hypothesis that the FI may serve as clinical tool to identify CI-implanted ears with reduced cochlear health and contacts close to areas of reduced SGN survival and/or integrity.