The mechanism of direct stimulation of the cochlea by vibrating the round window

Ronen Perez; Cahtia Adelman; Shai Chordekar; Marrigje A. de Jong; Haim Sohmer

doi:10.1515/jbcpp-2014-0042

Article

The mechanism of direct stimulation of the cochlea by vibrating the round window

Ronen Perez , Cahtia Adelman , Shai Chordekar , Marrigje A. de Jong and Haim Sohmer

Published/Copyright: July 19, 2014

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From the journal Journal of Basic and Clinical Physiology and Pharmacology Volume 25 Issue 3

Abstract

Background: Active middle ear implants such as the vibrant sound bridge (VSB) have been placed on the round window (RW) in patients with conductive or mixed hearing loss, with satisfactory hearing results. Several observations show that the mechanism of RW stimulation is not completely understood. The purpose of the present study was to compare different coupling procedures between the transducer and the RW in order to contribute to an understanding of the mechanism of RW stimulation.

Methods: Five fat sand rats underwent ablation of the left ear and opening of the right bulla, followed by baseline measurements of thresholds of auditory nerve brainstem evoked responses (ABR) to air and bone conduction click stimuli. Subsequently the malleus and incus were removed from the right middle ear, modeling a conductive hearing loss in which the VSB on the RW is indicated. In the next stage of the experiment, a rod attached to the bone vibrator was placed gently on the RW membrane and then on saline fluid applied to the RW niche. ABR thresholds were recorded following both placements.

Results: Mean baseline ABR threshold in response to air conduction stimuli was 48±4 dB; mean ABR threshold when the rod was placed on the dry RW membrane was 99±12 dB; mean ABR threshold when the rod was in the saline on RW niche was 79±7 dB.

Conclusions: ABR thresholds were better (lower) with stimulation of fluid on the RW membrane compared to direct stimulation of the RW, providing further evidence of a direct fluid pathway.

Keywords: basilar membrane; bone conduction; fluid; round window; soft tissue conduction; vibration

Corresponding author: Ronen Perez, Department of Otolaryngology and Head and Neck Surgery, Shaare Zedek Medical Center, Center affiliated with the Hebrew University Medical School, POB 3235, Jeruslalem 91031 Israel, E-mail: perezro@zahav.net.il

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Received: 2014-4-4

Accepted: 2014-5-14

Published Online: 2014-7-19

Published in Print: 2014-9-1

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Articles in the same Issue

https://doi.org/10.1515/jbcpp-2014-0042

Keywords for this article

basilar membrane; bone conduction; fluid; round window; soft tissue conduction; vibration