Tringali Stéphane, Koka Kanthaiah, Deveze Arnaud, Holland N Julian, Jenkins Herman A, Tollin Daniel J
Department of Physiology and Biophysics, University of Colorado Medical School, Aurora, Colo., USA.
Audiol Neurootol. 2010;15(5):291-302. doi: 10.1159/000283006. Epub 2010 Feb 11.
To assess the importance of 2 variables, transducer tip diameter and resection of the round window (RW) niche, affecting the optimization of the mechanical stimulation of the RW membrane with an active middle ear implant (AMEI).
Ten temporal bones were prepared with combined atticotomy and facial recess approach to expose the RW. An AMEI stimulated the RW with 2 ball tip diameters (0.5 and 1.0 mm) before and after the resection of the bony rim of the RW niche. The RW drive performance, assessed by stapes velocities using laser Doppler velocimetry, was analyzed in 3 frequency ranges: low (0.25-1 kHz), medium (1-3 kHz) and high (3-8 kHz).
Driving the RW produced mean peak stapes velocities (H(EV)) of 0.305 and 0.255 mm/s/V at 3.03 kHz, respectively, for the 1- and 0.5-mm tips, with the RW niche intact. Niche drilling increased the H(EV) to 0.73 and 0.832 mm/s/V for the 1- and 0.5-mm tips, respectively. The tip diameter produced no difference in output at low and medium frequencies; however, the 0.5-mm tip was 5 and 6 dB better than the 1-mm tip at high frequencies before and after niche drilling, respectively. Drilling the niche significantly improved the output by 4 dB at high frequencies for the 1-mm tip, and by 6 and 10 dB in the medium- and high-frequency ranges for the 0.5-mm tip.
The AMEI was able to successfully drive the RW membrane in cadaveric temporal bones using a classical facial recess approach. Stimulation of the RW membrane with an AMEI without drilling the niche is sufficient for successful hearing outputs. However, the resection of the bony rim of the RW niche significantly improved the RW stimulation at medium and higher frequencies. Drilling the niche enhances the exposure of the RW membrane and facilitates positioning the implant tip.
评估两个变量，即换能器尖端直径和圆窗龛切除术，对使用有源中耳植入物（AMEI）优化圆窗膜机械刺激的重要性。
采用上鼓室切开术和面隐窝联合入路制备10个颞骨，以暴露圆窗。在切除圆窗龛的骨边缘之前和之后，使用AMEI以两种球头直径（0.5和1.0毫米）刺激圆窗。使用激光多普勒测速仪通过镫骨速度评估圆窗驱动性能，在三个频率范围进行分析：低频（0.25 - 1千赫）、中频（1 - 3千赫）和高频（3 - 8千赫）。
对于1毫米和0.5毫米的尖端，在圆窗龛完整时，在3.03千赫驱动圆窗产生的平均镫骨峰值速度（H(EV)）分别为0.305和0.255毫米/秒/伏。圆窗龛钻孔后，1毫米和0.5毫米尖端的H(EV)分别增加到0.73和0.832毫米/秒/伏。尖端直径在低频和中频时输出无差异；然而，在圆窗龛钻孔前后，0.5毫米尖端在高频时分别比1毫米尖端好5分贝和6分贝。对于1毫米尖端，钻孔在高频时显著提高输出4分贝，对于0.5毫米尖端，在中频和高频范围分别提高6分贝和10分贝。
AMEI能够使用经典的面隐窝入路在尸体颞骨中成功驱动圆窗膜。不钻孔刺激圆窗膜的AMEI足以获得成功的听力输出。然而，切除圆窗龛的骨边缘在中高频时显著改善了圆窗刺激。钻孔圆窗龛可增强圆窗膜的暴露并便于植入物尖端的定位。
