Stimulating the cochlear apex without longer electrodes

项目摘要 耳蜗植入物（CI）电极阵列仅部分插入耳蜗，在大多数情况下， 超过一半的耳蜗没有受到刺激在正常听力的耳朵中，耳蜗区域没有受到刺激， 大多数CI表示低于约800 Hz的频率。为更广泛的 具有CI的耳蜗区域具有增强性能的潜力。例如，增加顶点 覆盖范围已被证明可以改善语音感知并加速CI患者对其设备的适应。 这些益处可能是由于低频信息的表示更接近正常耳蜗位置。 此外，比一个耳蜗圈更深的刺激可以提供对时间信息的更好感知 和更好的音质。然而，使用较长的电极阵列进入深根尖区域具有若干缺点。 缺点首先，由于鼓阶直径随着耳蜗深度的增加而减小， 不完全插入的可能性随着电极阵列长度而增加。第二，如果更深的插入是 当耳蜗导管壁变得狭窄时， 离电极更近。第三，即使是最长的电极也只能刺激耳蜗长度的70%。 为了解决这些缺点，我们开发了一种新的方法来刺激耳蜗尖 而不增加电极阵列长度。此外，我们的方法使用现有的FDA批准的 CI、语音处理器和商业拟合软件，无需修改。在COMEDIAR CI设备中， 两个耳蜗外电极（ECE）用于接地：ECE 1（通常放置在颞肌下 肌肉）和ECE 2（位于植入物外壳上）。在这种新方法中，ECE 1被放置在耳蜗中 通过顶端耳蜗造口术插入螺旋孔，并从耳蜗的基底端插入电极阵列 通过传统的耳蜗造口术当来自阵列的电极接地到耳蜗中的ECE 1时 Helicotrema，电场被驱动向耳蜗尖，刺激该部位的残留神经组织 比电极阵列和接地电极的标准配置更深。使用ECE2 因为地面提供单极刺激，这是临床标准。到目前为止，我们已经成功地 使用这种新的手术方法植入了三名患者，并实施了新的信号处理 使用ECE1电极。当使用ECE1而不是ECE2作为接地时，所有人都报告了较低的音调。 这种新方法提供了一个独特的机会来回答重要的科学问题， 评估新的临床干预措施。它提供了第一次直接刺激耳蜗的机会 helicotrema（apex）在人类中。我们现在可以研究这种刺激是否改善了时间编码（目标1）， 扩展音调拓扑音高范围（目标2）。此外，我们可以研究干预是否改善了临床 （目标3）。我们建议用这种新方法植入15名患者，以实现这三个目标。

PROJECT SUMMARY Cochlear implant (CI) electrode arrays are only partially inserted into the cochlea, in most cases leaving more than half of the cochlea unstimulated. In the normal hearing ear, the cochlear region left unstimulated by most CIs represents frequencies below approximately 800Hz. Providing electrical stimulation to a broader region of the cochlea with a CI has the potential to enhance performance. For example, increasing apical coverage has been shown to improve speech perception and accelerate CI patients’ adaptation to their device. These benefits may be due to representation of low-frequency information closer to the normal cochlear place. Furthermore, stimulation deeper than one cochlear turn may provide better perception of temporal information and better sound quality. However, using longer electrode arrays to access deep apical regions has several disadvantages. First, because the scala tympani diameter decreases with increasing cochlear depth, the likelihood of an incomplete insertion increases with electrode array length. Second, if deeper insertion is achieved, the probability of damage to cochlear structures increases as the walls of the cochlear duct become closer to the electrode. Third, even the longest electrodes only stimulate ~70% of the cochlear length. To address these shortcomings, we developed a novel approach to stimulate the cochlear apex without increasing the electrode array length. Moreover, our approach uses existing FDA-approved CIs, speech processors, and commercial fitting software without modification. In Cochlear CI devices, two extra-cochlear electrodes (ECEs) are used for grounds: ECE1 (usually placed under the temporalis muscle) and ECE2 (located on the implant case). In the novel approach, ECE1 is placed into the cochlear helicotrema via an apical cochleostomy and the electrode array is inserted from the basal end of the cochlea through a traditional cochleostomy. When an electrode from the array is grounded to ECE1 in the cochlear helicotrema, the electric field is driven towards the cochlear apex, stimulating residual neural tissue at sites deeper than available with the standard configuration of electrode arrays and ground electrodes. Using ECE2 as the ground provides monopolar stimulation, which is the clinical standard. Thus far, we have successfully implanted three patients using this novel surgical approach and implemented novel signal processing using the ECE1 electrode. All reported a lower pitch when using ECE1 instead of ECE2 as a ground. This new approach provides a unique opportunity to answer important scientific questions and to evaluate a new clinical intervention. It provides the first opportunity to directly stimulate the cochlear helicotrema (apex) in humans. We can now study if such stimulation improves temporal coding (Aim 1) and extends the tonotopic pitch range (Aim 2). Additionally, we can study if the intervention improves clinical outcomes (Aim 3). We propose to implant 15 patients with this new approach to address the three aims.