University Department of ENT, Head and Neck Surgery, Inselspital, University of Bern, Switzerland.
Hear Res. 2010 May;263(1-2):120-7. doi: 10.1016/j.heares.2009.12.019. Epub 2009 Dec 22.
The round window placement of a floating mass transducer (FMT) is a new approach for coupling an implantable hearing system to the cochlea. We evaluated the vibration transfer to the cochlear fluids of an FMT placed at the round window (rwFMT) with special attention to the role of bone conduction. A posterior tympanotomy was performed on eleven ears of seven human whole head specimens. Several rwFMT setups were examined using laser Doppler vibrometry measurements at the stapes and the promontory. In three ears, the vibrations of a bone anchored hearing aid (BAHA) and an FMT fixed to the promontory (pFMT) were compared to explore the role of bone conduction. Vibration transmission to the measuring point at the stapes was best when the rwFMT was perpendicularly placed in the round window and underlayed with connective tissue. Fixation of the rwFMT to the round window exhibited significantly lower vibration transmission. Although measurable, bone conduction from the pFMT was much lower than that of the BAHA. Our results suggest that the rwFMT does not act as a small bone anchored hearing aid, but instead, acts as a direct vibratory stimulator of the round window membrane.
圆形窗内置式浮动质量换能器（FMT）是将植入式听觉系统与耳蜗耦合的一种新方法。我们评估了置于圆形窗（rwFMT）处的 FMT 向耳蜗液传递振动的情况，特别关注骨导的作用。对 7 个人类全头颅标本的 11 只耳朵进行了后鼓室切开术。使用激光多普勒测振仪在镫骨和前庭测量了几种 rwFMT 设置的振动。在 3 只耳朵中，比较了固定于前庭的骨锚式助听器（BAHA）和 FMT（pFMT）的振动，以探讨骨导的作用。当 rwFMT 垂直置于圆形窗并用结缔组织覆盖时，向镫骨测量点传递的振动最佳。rwFMT 固定于圆形窗时，振动传递明显降低。尽管可测量，但 pFMT 的骨导远低于 BAHA。我们的结果表明，rwFMT 不作为小型骨锚式助听器起作用，而是作为圆窗膜的直接振动刺激器。
