2019 Conference on Implantable Auditory Prostheses

14-19 July 2019

Granlibakken, Lake Tahoe

Page 95

M4: THE CONCEPT OF INDIVIDUALIZED COCHLEAR IMPLANTATION

Thomas Lenarz, Rolf Benedikt Salcher, Nils Kristian Prenzler,

Daniel Kley, Anke Lesinski-Schiedat, Andreas Buechner

Medizinische Hochschule Hannover, Hannover, DEU

Background: Individualized Cochlear Implantation - meaning an individual selection of electrode

insertion depth and stimulation modality (electric-acoustic stimulation (EAS) or electric

stimulation (ES)) - aims for the best possible hearing outcome for every patient. Important

factors to take into account are hearing preservation and an optimal cochlear coverage.

Shorter electrodes show better hearing preservation results and very good speech perception

results in EAS. Longer electrodes show a higher cochlear coverage and better speech

perception results in ES, but show worse hearing preservation results.

The concept of partial insertion could overcome this trade-off. If a longer electrode is partially

inserted for EAS, it gives the option for a further adaption for ES in case of progressive hearing

loss.

Methods: N=20 patients were treated with a partial insertion and an individual selected insertion

depth. Using statistical models, the postoperative residual hearing and electrode location in the

cochlea were individually predicted and supported the surgeon to select best suitable electrode

insertion depth. In n=6 cases a 24 mm long electrode was partially inserted with an average

insertion depth of 20.2 mm and in n=14 cases a 28 mm long electrode was partially inserted

20.7 mm in average. To document the patient outcomes pre- and postoperative hearing

thresholds and speech perception in noise were determined.

Results: The median hearing loss at first activation was 21.5 dB (n=6) for a partially inserted

electrode of 24 mm length and 16 dB (n=13) for a partially inserted electrode of 28 mm length

and improved to 13 dB (24 mm long electrode; n=4) and to 11 dB (28 mm long electrode; n=10)

to 6 months. N=14 patients used their low-frequency hearing for EAS and achieved in median

74% with the HSM sentence test in noise at 10 dB SNR at 3 months and improved to 86% at 6

months. Two patients did not use an acoustic amplification and achieved 24% in noise in ES.

Conclusion: The concept of individualized cochlear implantation allows for a patient specific

choice of electrode insertion depth and modality. Taking cochlear geometry and the prediction of

postoperative residual hearing into account, an optimal cochlear coverage, optimal hearing

preservation results and the best individual outcomes can be achieved. Patients treated with

partial insertion can benefit from EAS. If hearing is progressive over time, partial insertion allows

for further, patient specific adaptation of the insertion depth.