Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland.
Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland.
Hear Res. 2021 Jun;405:108235. doi: 10.1016/j.heares.2021.108235. Epub 2021 Apr 14.
A limiting factor of cochlear implant technology is the spread of electrode-generated intracochlear electrical field (EF) leading to spread of neural excitation (SOE). In this study, we investigated the relation of the spread of the intracochlear EF, assessed via transimpedance matrix (TIM), and SOE. A total of 43 consecutive patients (ages 0.7-82 years; 31.0 ± 25.7 years, mean ± SD) implanted with a Cochlear Nucleus CI522 or CI622 cochlear implant with Slim Straight electrode array (altogether 51 ears) were included in the study. Cochlear nerve was visualized for all patients in preoperative imaging and there were no cochlear anomalies in the study sample. The stimulated electrodes were in the basal, middle, and apical parts of the electrode array (electrode numbers 6, 11, and 19, respectively). The stimulation level was 210 CL on average for the TIM measurement and always 230 CL for the SOE measurement. Approximately 90% of the individual TIM and SOE profiles correlated with each other (p < .05; r = 0.61-0.99). Also, the widths of the TIM and SOE peaks, computed at 50% of the maximum height, exhibited a weak correlation (r = 0.39, p = .007). The 50% widths of TIM and SOE were the same only in the apical part of the electrode array; in the basal part SOE was wider than TIM, and in the middle part TIM was wider than SOE (p < .01 and p = .048, respectively). Within each measurement, TIM 50% widths were different between all three parts of the electrode array, while for SOE, only the basal electrode differed from the middle electrode. Finally, the size of the cochlea and the 50% widths of TIM and SOE had the strongest correlation in the middle part of the electrode array (r = -0.63, and -0.37, respectively). Our results suggest that there is a correlation between the spread of intracochlear EF and neural SOE at least in the apical part of the electrode array used in this study, and that larger cochleae are associated with more focused TIM and SOE.
耳蜗植入技术的一个限制因素是电极产生的耳蜗内电场（EF）的扩散，导致神经兴奋的扩散（SOE）。在这项研究中，我们研究了通过跨阻矩阵（TIM）评估的耳蜗内 EF 扩散与 SOE 的关系。共纳入 43 例连续患者（年龄 0.7-82 岁；31.0±25.7 岁，均值±标准差），均植入 Cochlear Nucleus CI522 或 CI622 耳蜗植入物和 Slim Straight 电极阵列（共 51 只耳朵）。所有患者在术前影像学检查中均可见耳蜗神经，研究样本中无耳蜗异常。刺激电极分别位于电极阵列的基底、中间和顶部（电极编号分别为 6、11 和 19）。TIM 测量的平均刺激水平为 210 CL，SOE 测量的平均刺激水平始终为 230 CL。大约 90%的个体 TIM 和 SOE 谱彼此相关（p<0.05；r=0.61-0.99）。此外，在最大高度的 50%处计算的 TIM 和 SOE 峰的宽度也呈弱相关（r=0.39，p=0.007）。仅在电极阵列的顶部，TIM 和 SOE 的 50%宽度相同；在基底部分，SOE 比 TIM 宽，在中间部分 TIM 比 SOE 宽（p<0.01 和 p=0.048，分别）。在每个测量中，TIM 的 50%宽度在电极阵列的三个部分之间均不同，而对于 SOE，仅基底电极与中间电极不同。最后，在电极阵列的中间部分，耳蜗的大小以及 TIM 和 SOE 的 50%宽度之间的相关性最强（r=-0.63 和-0.37）。我们的结果表明，在这项研究中使用的电极阵列的顶部部分，至少存在耳蜗内 EF 扩散和神经 SOE 之间的相关性，并且较大的耳蜗与更集中的 TIM 和 SOE 相关。
