Department Otolaryngology, University of Melbourne, Victoria, Australia.
Royal Victorian Eye and Ear Hospital, Victoria, Australia.
Ear Hear. 2023;44(5):1088-1106. doi: 10.1097/AUD.0000000000001347. Epub 2023 Mar 20.
The underlying state of cochlear and neural tissue function is known to affect postoperative speech perception following cochlear implantation. The ability to assess these tissues in patients can be performed using intracochlear electrocochleography (IC ECochG). One component of ECochG is the summating potential (SP) that appears to be generated by multiple cochlear tissues. Its qualities may be able to detect the presence of functional inner hair cells, but evidence for this is limited in human cochleae. This study aimed to examine the IC SP characteristics in cochlear implantation recipients, its relationship to preoperative speech perception and audiometric thresholds, and to other IC ECochG components.
This is a retrospective analysis of 113 patients' IC ECochG recordings across the array in response to a 500 Hz tone burst stimulus. Responses to condensation and rarefaction stimuli were then subtracted from one another to emphasize the cochlear microphonic and added to one another to emphasize the SP, auditory nerve neurophonic, and compound action potential. Patients were grouped based on their maximum SP deflection being large and positive (+SP), large and negative (-SP), or minimal (0 SP) to further investigate these relationships.
Patients in the +SP group had better preoperative speech perception (mean consonant-vowel-consonant phoneme score 46%) compared to the -SP and 0 SP groups (consonant-vowel-consonant phoneme scores 34% and 36%, respectively, difference to +SP: p < 0.05). Audiometric thresholds were lowest for +SP (mean pure-tone average 50 dB HL), then -SP (65 dB HL), and highest for 0 SP patients (70 dB HL), but there was not a statistical significance between +SP and -SP groups ( p > 0.1). There were also distinct differences between SP groups in the qualities of their other ECochG components. These included the +SP patients having larger cochlear microphonic maximum amplitude, more apical SP peak electrode locations, and a more spatially specific SP magnitude growth pattern across the array.
Patients with large positive SP deflection in IC ECochG have preoperatively better speech perception and lower audiometric thresholds than those without. Patterns in other ECochG components suggest its positive deflection may be an indicator of cochlear function.
已知耳蜗和神经组织功能的基础状态会影响耳蜗植入后的术后言语感知。可以使用耳蜗内电 CochG（IC ECochG）来评估患者的这些组织。ECochG 的一个组成部分是总和电位（SP），它似乎是由多个耳蜗组织产生的。其特性可能能够检测到功能性内毛细胞的存在，但在人类耳蜗中，这方面的证据有限。本研究旨在检查耳蜗植入接受者的 IC SP 特征，及其与术前言语感知和听力阈值的关系，以及与其他 IC ECochG 成分的关系。
这是对 113 名患者的 IC ECochG 记录在响应 500Hz 声爆发刺激时在整个数组上的回顾性分析。然后将压缩和稀疏刺激的响应相互减去以强调耳蜗微音，将它们相加以强调总和电位、听神经神经音和复合动作电位。根据最大 SP 偏转的大小和正负（+SP、-SP 或 0 SP）将患者分组，以进一步研究这些关系。
+SP 组的患者术前言语感知更好（平均辅音-元音-辅音音位得分 46%），与-SP 和 0 SP 组相比（辅音-元音-辅音音位得分分别为 34%和 36%，与+SP 组的差异：p < 0.05）。+SP 组的听力阈值最低（平均纯音平均 50dB HL），然后是-SP 组（65dB HL），0 SP 患者的听力阈值最高（70dB HL），但+SP 和-SP 组之间没有统计学意义（p > 0.1）。SP 组之间的其他 ECochG 成分的质量也有明显差异。这包括+SP 患者的耳蜗微音最大振幅更大，SP 峰电极位置更接近顶端，以及在整个数组上的 SP 幅度增长模式更具空间特异性。
在 IC ECochG 中具有大的正 SP 偏转的患者术前言语感知更好，听力阈值更低。其他 ECochG 成分的模式表明，其正偏转可能是耳蜗功能的指标。
