Intraoperative adjustments to optimize active middle ear implant performance
Source: Acta Oto-Laryngologica, Volume 131, Number 1, January 2011 , pp. 27-35(9)
Publisher: Informa Healthcare
Conclusion: After initial contact of the active middle ear implant (AMEI) on the incus, significant increases in device performance can be achieved intraoperatively without affecting residual hearing by additional static loading of the incus with 62 m (quarter turn) to 125 m (half turn) increments via an adjustment screw. Objectives: To assess the performance gains of driving the incus with an AMEI under increasing static loads in cadaveric temporal bones. Methods: Incus drive efficacy was assessed using laser Doppler velocimetry measurements of stapes velocities over a frequency range of 0.25 to 8 kHz. Results were compared to stapes velocities following acoustic stimulation via insert earphone. Maximum equivalent ear canal sound pressure level (LEmax) and residual hearing loss after initial loading of the AMEI (first contact) were compared in each temporal bone. Additional increases in incus load were induced by turning an adjustment screw in quarter turn steps, corresponding to 62 m increments per step. LEmaxand residual hearing loss were reassessed after each step. For each temporal bone, experiments were repeated for three different AMEIs. Results: On average across bones, incus stimulation upon initial contact produced an LEmaxof 125, 127, and 121 dB SPL and residual hearing losses of ––2, ––1, and ––1 dB with respect to unloaded, unaided conditions for the three AMEIs, respectively. Across bones and transducers, increasing static transducer load by incrementing the AMEI up to 125 m significantly improved performance without affecting residual hearing loss. Loading beyond 125 m (half turn) did not improve performance but significantly increased residual hearing loss.
Document Type: Research Article
Affiliations: 1: 1Department of Otolaryngology 2: 2Department of Physiology and Biophysics, University of Colorado Medical School, Aurora, USA 3: 5Department of Otolaryngology, University Hospital Nord, Assistance Publique Hôôpitaux de Marseille, Marseille
Publication date: January 1, 2011