Effect of pressure changes on middle ear actuator coupling efficiency

Introduction An option to treat moderate to severe sensorineural (SNHL) and mixed hearing loss (MHL) is the implantation of an active middle ear implant like the Cochlear™ Carina^® System. Clinicians and recipients need assurance that the coupling will be stable over time, even with movements of the ossicular chain caused by slow or sudden changes in ambient barometric pressure. Therefore we designed a temporal bone study to test whether pressure fluctuations to the middle ear expected from daily life events could potentially impact the connection to the ossicular chain to change coupling efficiency of the actuator.

Methods Experiments were performed on fresh frozen human temporal bones. Two daily-life pressure events were tested; Valsalva’s maneuvers (simulated with 500 cycles of -40 hPa - +60 hPa) and jumping into a swimming pool and diving 3 meters deep (simulated with a steep change of 300 hPa). Actuator coupling efficiency was measured before and after the pressure events through laser Doppler vibrometric measurements of stapes motion. Three different coupling configurations were tested; coupling to the incus body, coupling to a small hole to the incus body made by a surgical laser (standard procedure at Hannover Medical School) and coupling to the long process of the incus with an áWengen clip.

Results and conclusion All 3 coupling configurations connected the actuator securely to the ossicular chain and coupling efficiency changed by less than dB for both pressure events. Only at individual frequencies above 1 kHz larger changes were seen in 1 temporal bone.

Conclusion Coupling of the Carina^® system was stable in most experiments simulating Valsalva’s maneuver and single pressure events.

Poster-PDF A-1303.PDF

U. A. Gamm ist Angestellte von Cochlear Ltd.

Publication History

Article published online:
10 June 2020