Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
Emmeline Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Clin Otolaryngol. 2022 Nov;47(6):641-649. doi: 10.1111/coa.13963. Epub 2022 Aug 1.
To investigate the value of scalp surface potentials to identify and manage partial short circuits to ground in cochlear implant electrodes.
A retrospective review of patients with suspected partial short circuits.
Electrical output of individual electrodes was measured using scalp surface potentials for patients reporting a change in hearing function. Electrical output was compared to functional performance and impedance measurements to determine if devices with suspected partial short circuits were experiencing a decrease in performance as a result of reduced electrical output. Electrical output was checked in an artificial cochlea for two implants following explant surgery to confirm scalp surface potential results.
All patients with suspected partial short circuits (n = 49) had reduced electrical output, a drop in impedances to approximately ½ of previously stable measurements or to below 2 kΩ, an atypical electrical field measurement (EFI) and a decline in hearing function. Only devices with an atypical EFI showed reduced electrical output. Results of scalp based surface potentials could be replicated in an artificial cochlea following explantation of the device. All explant reports received to date (n = 42) have confirmed partial short circuits, with an additional four devices failing integrity tests.
Surface potential measurements can detect partial shorts and had 100% correlation with atypical EFI measurements, which are characteristic of a partial short to ground in this device. Surface potentials can help determine the degree to which the electrode array is affected, particularly when behavioural testing is limited or not possible.
探讨头皮表面电位在识别和处理人工耳蜗电极部分对地短路中的作用。
回顾性分析疑似部分对地短路患者的资料。
报告听力功能改变的患者采用头皮表面电位测量个别电极的电输出。将电输出与功能表现和阻抗测量进行比较，以确定疑似部分对地短路的设备是否因电输出降低而导致性能下降。在 2 例经手术取出植入体后的人工耳蜗中检查电输出，以确认头皮表面电位结果。
所有疑似部分对地短路的患者（n=49）均出现电输出降低，阻抗降至之前稳定测量值的约 1/2 或降至 2 kΩ以下，出现异常电场指数（EFI），听力功能下降。只有出现异常 EFI 的设备显示电输出降低。在取出设备后，在人工耳蜗中可以复制基于头皮的表面电位的结果。迄今为止收到的所有植入物取出报告（n=42）均证实存在部分短路，另有 4 个设备未通过完整性测试。
表面电位测量可检测部分短路，与异常 EFI 测量具有 100%相关性，这是该设备中部分对地短路的特征。表面电位有助于确定电极阵列受影响的程度，特别是在行为测试受限或不可能进行时。
