Characterization and Modelling of the Electrode-Nerve Interface for Electro-Acoustic Stimulation in Cochlear Implant Users

每天都有更多的具有残余听力的人接受人工耳蜗植入物（CI）以获得电声刺激（EAS），即从CI电极以电方式和通过助听器（HA）以声学方式递送的组合听觉刺激。对于EAS用户，低频声学听觉几乎不产生对噪声中的语音的识别，但是当与CI提供的电听觉相结合时，性能显著增强。然而，声刺激和电刺激模态如何相互作用仍然是未知的。临床经验发现，一些EAS用户根本不使用HA，仅依赖于电刺激。此外，已经观察到，EAS用户需要更多的时间来实现他们的最大性能与CI单独比常规CI用户。这些局限性可能会影响EAS植入标准的确定。这些限制的可能解释是声刺激和电刺激之间的相互作用。这些相互作用对于具有大残余听力的人变得越来越重要，因为电刺激和声刺激之间的重叠更大。 例如，已经表明，EAS设备所规定的听力损失的范围越来越接近与年龄相关的听力损失的范围。年龄相关性听力损失（EAS）的特征是高频听力损失。鉴于欧洲人口正在老龄化，听力损失相关问题增加，需要新的治疗方法来康复与年龄相关的听力损失患者。认知能力下降和听力损失似乎是相关的，EAS等新的治疗方法非常有希望改善老年人的生活质量。 这项工作是关于表征声刺激和电刺激之间的相互作用。表征将包括EAS用户的心理物理、电生理、成像和反向遥测测量。在精神病学上，声电相互作用将通过同时或前掩蔽实验来测量。 将使用每名研究参与者的锥形束计算机断层扫描（CBCT）评估插入深度和电极位置。植入体后向遥测的电场成像（EEG）将用于表征电极神经元界面，最后，耳蜗电描记术（eChochG）测量将用于评估神经水平上声刺激和电刺激之间的重叠。 该项目的成果是数据集，拟合程序和模型表征每个EAS用户的声电刺激之间的相互作用。这些结果可用于优化EAS设备的配置，并评估EAS植入的适应症是否可能扩展到与年龄相关的听力损失患者。

Everyday more people with residual hearing receive cochlear implants (CIs) to obtain electroacoustic stimulation (EAS), i.e. combined auditory stimulation delivered electrically from CI electrodes and acoustically through a hearing aid (HA). For EAS users low frequency acoustic hearing produces almost no recognition for speech in noise, but the performance is significantly enhanced when combined with the electric hearing delivered by the CI. However, it is still unknown how the acoustic and electric stimulation modalities interact with each other. Clinical experience has found that some EAS users do not use the HA at all and rely solely on electric stimulation. Moreover, it has been observed that EAS users require more time to achieve their maximum performance with the CI alone than regular CI users. These limitations may have influence in defining the implantation criteria of EAS. Possible explanations for these limitations are interactions between acoustic and electric stimulation. These interactions become more and more important for people with large residual hearing because the overlap between electric and acoustic stimulation is larger. For example, it has been shown that the range of hearing loss for which EAS devices are prescribed is getting closer to the range of age related hearing loss. Age related hearing loss, as EAS, is characterized by lost of audibility in the high frequencies. Given that the population in Europe is becoming older with increased hearing loss related problems new treatments are required to rehabilitate people with age related hearing loss. Cognitive decline and hearing loss seem to be related and new treatments such as EAS are very promising to improve quality of life of the elderly population. This work is about characterizing the interaction between acoustic and electric stimulation. The characterization will consist of psychophysical, electrophysiological, imaging and backward telemetry measures in EAS users. Psychophysically, the acoustic and electric interaction will be measured by means of simultaneous or forward masking experiments. Cone beam computer tomography (CBCT) for each study participant will be used to assess the insertion depth and electrode positions. Electrical field imaging (EFI) from the backward telemetry of the implant will be used to characterize the electrode neuron interface, and finally electrocochleography (eChochG) measures will be used to assess the overlap between acoustic and electric stimulation at the neural level. The outcomes of this project are datasets, fitting procedures and a model characterizing the interaction between acoustic and electric stimulation of each EAS user. These outcomes have application to optimize the configuration of EAS devices and to assess whether the indication for EAS implantation can be potentially extended to people with age related hearing loss.