Redesign of the Hannover Coupler: Optimized Vibration Transfer from Floating Mass Transducer to Round Window.

Mathias Müller,Thomas Lenarz,Rolf Salcher,Hannes Maier,Nils Prenzler

doi:10.1155/2018/3701954

Abstract

Introduction In order to reduce the large variations in clinical outcomes of patients with implanted MED-EL Floating Mass Transducer (FMT) at the round window (RW), several approaches were proposed to optimize FMT-RW coupling. Our previous study showed improved FMT-RW coupling by applying static RW loads utilizing the “Hannover Coupler” (HC) FMT-prosthesis but also demonstrated insufficient low frequency performance. Hence, a redesigned HC version (HCv2) was investigated in this study. Methods Experiments were performed in ASTM F2504-05 compliant fresh human temporal bones. The HCv2 is a FMT-prosthesis redesigned from a previous prototype to specifically improve low frequency performance. Stapes footplate (SFP) displacements in response to acoustic stimulation of the tympanic membrane and to FMT-RW stimulation at varying static force (0–100 mN) were measured by Laser-Doppler vibrometry. Results SFP displacements were highly dependent on the applied RW load and had a global maximum at 15 mN when averaged at speech relevant frequencies (0.5–4 kHz). SFP responses at frequencies ≤ 1 kHz were up to 25 dB higher than responses achieved with the previous HC version. Conclusion Optimizing the HC prosthesis design resulted in improved SFP responses to RW stimulation especially at lower frequencies (≤1 kHz).

Highlights

In order to reduce the large variations in clinical outcomes of patients with implanted MED-EL Floating Mass Transducer (FMT) at the round window (RW), several approaches were proposed to optimize FMT-RW coupling
The MED-EL Vibrant Soundbridge5 (VSB) is an active middle ear implant (AMEI) with a Floating Mass Transducer (FMT) that is typically attached to the long process of the incus of the ossicular chain
In this work we systematically investigated the performance of a redesigned and optimized version of the HC termed “Hannover Coupler v2” (HCv2) and its influence on RW stimulation by applying well defined static forces to the round window membrane (RWM) (0–100 Mean Force (mN))

Summary

Introduction

In order to reduce the large variations in clinical outcomes of patients with implanted MED-EL Floating Mass Transducer (FMT) at the round window (RW), several approaches were proposed to optimize FMT-RW coupling. Our previous study showed improved FMT-RW coupling by applying static RW loads utilizing the “Hannover Coupler” (HC) FMT-prosthesis and demonstrated insufficient low frequency performance. The HCv2 is a FMT-prosthesis redesigned from a previous prototype to improve low frequency performance. Optimizing the HC prosthesis design resulted in improved SFP responses to RW stimulation especially at lower frequencies (≤1 kHz). The MED-EL Vibrant Soundbridge (VSB) is an active middle ear implant (AMEI) with a Floating Mass Transducer (FMT) that is typically attached to the long process of the incus of the ossicular chain. Placement of the FMT at the round window membrane (RWM) remains surgically challenging [2] and RW stimulation is still subject to large variations in clinical outcomes [3, 4]

Methods

Results

Discussion

Conclusion