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人工耳蜗是一种植入式电子设备,是目前为重度、极度听力损失患者重建听力的最行之有效的临床治疗方法。人工耳蜗术后患者残余听力的水平取决于多种复杂因素,尚未被完全了解。本研究聚焦在人工耳蜗植入后对于耳蜗动力学特性产生的影响。通过建立的生物力学模型对比人工耳蜗植入前后基底膜响应,进而得到可能的听力损失情况。所采用的耳蜗模型为被动式,不存在对低声压级信号的放大过程,这是由于大部分人工耳蜗患者的听力阈值较高,耳蜗在高声压级信号激励时其响应具有线性、无主动增益特性。计算结果显示,由于人工耳蜗植入带来的淋巴液体积变化对基底膜振动速度影响不大,在低频范围内最多造成3 dB听力损失。还假设了两种极端情况,即部分或者全部植入的电极与基底膜相接触并阻止其产生响应。在全部电极与基底膜接触情况下,虽然接触部分的基底膜无法运动,但是镫骨位置的激励还是可以通过耳蜗内的不可压缩流体传递至基底膜剩余完好位置。在这些极端假设情况下,低频激励下的基底膜响应并未受到太大影响,仅是电极末端位置对应的听觉特征频率受影响较大。虽然研究不能解释造成人工耳蜗植入后残余听力损失的全部原因,但研究结果表明人工耳蜗植入带来的耳蜗动力学特性改变对残余听力的影响不大。
Cochlear implants are implanted electronic devices and are currently the most effective clinical treatment for rebuilding hearing in patients with severe and profound hearing loss. The level of residual hearing in cochlear implants depends on a variety of complications and is not fully understood. This study focused on the effects of cochlear implants on cochlear kinetic characteristics. The established biomechanical model was used to compare basement membrane responses before and after cochlear implantation to obtain possible hearing loss. The adopted cochlear model is passive and there is no amplification of the low SPL signal due to the high hearing threshold of most cochlear implants and the cochlear response to the loud SPL signal is linear and inactive Gain characteristics. The calculated results show that due to the change of lymph volume caused by cochlear implants, the vibration velocity of the basement membrane is not greatly affected, and at most 3 dB of hearing loss is caused in the low frequency range. Also assumed are two extreme cases where some or all of the implanted electrodes are in contact with the basement membrane and prevent their response. In the case where all the electrodes are in contact with the basement membrane, although the basement membrane at the contact portion can not move, the excitation of the stapes site can still be transmitted to the remaining intact basement membrane through the incompressible fluid in the cochlea. Under these extreme hypotheses, the basement membrane response at low frequency stimulation is not significantly affected, except that the frequency of the auditory features corresponding to the electrode tip location is more affected. Although the study can not explain all the causes of residual hearing loss after cochlear implantation, the results show that cochlear implants caused by cochlear implants have little effect on residual hearing.