Superior-semicircular-canal dehiscence: Effects of location, shape, and size on sound conduction
Superior-semicircular-canal dehiscence: Effects of location, shape, and size on sound conduction
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DOI：
10.1016/j.heares.2013.03.008
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发表时间：
2013-07-01
期刊：
影响因子：
2.8
通讯作者：
Puria, Sunil
中科院分区：
文献类型：
--
作者：
Kim, Namkeun;Steele, Charles R.;Puria, Sunil
采用人中耳与内耳耦合的三维有限元模型，研究上半规管裂开(SSCD)通过气导(AC)和骨传导(BC)通路对听力的影响。通过移除SSC外骨壁的一部分并对暴露的流体表面施加零压力条件来模拟开裂。在每个频率下，分别计算裂开前和裂开后AC和BC刺激时的基底膜速度v(Bm)。听力损失计算为裂开前和裂开后代表听力阈值变化的v(BM)最大幅值的差值。在这项研究中，通过沿模型(任意定义)x、y和z轴的方向对模型施加刚体振动来模拟BC激励。模拟结果与先前对SSCD患者的临床测量和早期集总元件电路模型研究的结果一致，对于低频BC激励，开裂降低了听力阈值(即，增加v(BM)约35分贝)，而对于交流激励，开裂使听力阈值(即，降低V(BM))增加了约15分贝。这项研究的一个新发现是，裂口前庭一侧的初始宽度(定义为来自椭圆形窗口的流体运动波第一次与之相遇的裂口边缘的宽度)对v(BM)的影响大于裂口面积。利用有限元模型对开裂效应的分析进一步预测，改变BC激发的方向将对v(Bm)产生影响，由于BC激发平行于钩区BM的纵向(x方向)，与其他方向(y和z)的激发相比，v(Bm)降低约20d B。与BC激励的其他方向相比，x方向的BC激励和沿SSC长度中途的“中心”裂开导致BM上流体压力的反对称分量减少，从而导致高频时v(BM)的减小。本文是题为“Memro 2012”的特刊的一部分。(C)Elsevier B.V.出版的2013年
The effects of a superior-semicircular-canal (SSC) dehiscence (SSCD) on hearing sensitivity via the air-conduction (AC) and bone-conduction (BC) pathways were investigated using a three-dimensional finite-element (FE) model of a human middle ear coupled to the inner ear. Dehiscences were modeled by removing a section of the outer bony wall of the SSC and applying a zero-pressure condition to the fluid surface thus exposed. At each frequency, the basilar-membrane velocity, v(BM), was separately calculated for AC and BC stimulation, under both pre- and post-dehiscence conditions. Hearing loss was calculated as the difference in the maximum magnitudes of v(BM) between the pre- and post-dehiscence conditions representing a change in hearing threshold. In this study, BC excitations were simulated by applying rigid-body vibrations to the model along the directions of the (arbitrarily defined) x, y, and z axes of the model.Simulation results are consistent with previous clinical measurements on patients with an SSCD and with results from earlier lumped-element electrical-circuit modeling studies, with the dehiscence decreasing the hearing threshold (i.e., increasing v(BM)) by about 35 dB for BC excitation at low frequencies, while for AC excitation the dehiscence increases the hearing threshold (i.e., decreases v(BM)) by about 15 dB. A new finding from this study is that the initial width (defined as the width of the edge of the dehiscence where the flow of the fluid-motion wave from the oval window meets it for the first time) on the vestibular side of the dehiscence has more of an effect on v(BM) than the area of the dehiscence. Analyses of dehiscence effects using the FE model further predict that changing the direction of the BC excitation should have an effect on v(BM), with v(BM) being about 20 dB lower due to BC excitation parallel to the longitudinal direction of the BM in the hook region (the x direction) as compared to excitations in other directions (y and z). BC excitation in the x direction and with a 'center' dehiscence located midway along the length of the SSC causes a reduction in the anti-symmetric component of the fluid pressure across the BM, as compared to the other directions of BC excitation, which results in a decrease in v(BM) at high frequencies. This article is part of a Special Issue entitled "MEMRO 2012". (C) 2013 Published by Elsevier B.V.