Riojas Katherine E, Bruns Trevor L, Granna Josephine, Webster Robert J, Labadie Robert F
Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, USA.
Department of Otolaryngology, Medical University of South Carolina, Charleston, SC, USA.
Int J Comput Assist Radiol Surg. 2023 Mar;18(3):413-421. doi: 10.1007/s11548-022-02772-3. Epub 2022 Nov 4.
During traditional insertion of cochlear implant (CI) electrode arrays (EAs), surgeons rely on limited tactile feedback and visualization of the EA entering the cochlea to control the insertion. One insertion approach for precurved EAs involves slightly overinserting the EA and then retracting it slightly to achieve closer hugging of the modiolus. In this work, we investigate whether electrical impedance sensing could be a valuable real-time feedback tool to advise this pullback technique.
Using a to-scale 3D-printed scala tympani model, a robotic insertion tool, and a custom impedance sensing system, we performed experiments to assess the bipolar insertion impedance profiles for a cochlear CI532/632 precurved EA. Four pairs of contacts from the 22 electrode contacts were chosen based on preliminary testing and monitored in real time to halt the robotic insertion once the closest modiolar position had been achieved but prior to when the angular insertion depth (AID) would be reduced.
In this setting, the open-loop robotic insertion impedance profiles were very consistent between trials. The exit of each contact from the external stylet of this EA was clearly discernible on the impedance profile. In closed-loop experiments using the pullback technique, the average distance from the electrode contacts to the modiolus was reduced without greatly affecting the AID by using impedance feedback in real time to determine when to stop EA retraction.
Impedance sensing, and specifically the access resistance component of impedance, could be a valuable real-time feedback tool in the operating room during CI EA insertion. Future work should more thoroughly analyze the effects of more realistic operating room conditions and inter-patient variability on this technique.
在传统的人工耳蜗（CI）电极阵列（EA）插入过程中，外科医生依靠有限的触觉反馈以及观察EA进入耳蜗的情况来控制插入操作。一种预弯曲EA的插入方法是先稍微过度插入EA，然后再稍微回撤，以实现与蜗轴更紧密的贴合。在本研究中，我们探讨电阻抗传感是否可以作为一种有价值的实时反馈工具，为这种回撤技术提供指导。
使用按比例3D打印的鼓阶模型、机器人插入工具和定制的阻抗传感系统，我们进行了实验，以评估耳蜗CI532/632预弯曲EA的双极插入阻抗曲线。根据初步测试，从22个电极触点中选择了四对触点，并进行实时监测，一旦达到最接近蜗轴的位置，但在角插入深度（AID）减小之前，就停止机器人插入。
在这种情况下，各次试验之间的开环机器人插入阻抗曲线非常一致。该EA的每个触点从外部探针退出的情况在阻抗曲线上清晰可见。在使用回撤技术的闭环实验中，通过实时使用阻抗反馈来确定何时停止EA回撤，电极触点到蜗轴的平均距离减小，而对AID没有太大影响。
阻抗传感，特别是阻抗的接入电阻分量，在CI EA插入手术过程中可能是一种有价值的实时反馈工具。未来的工作应该更全面地分析更现实的手术室条件和患者间变异性对该技术的影响。
