Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland.
National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, Maryland.
Otol Neurotol. 2022 Jul 1;43(6):666-675. doi: 10.1097/MAO.0000000000003538.
Bilateral cochlear-implant (BI-CI) users will have a range of interaural insertion-depth mismatch because of different array placement or characteristics. Mismatch will be larger for electrodes located near the apex or outside scala tympani, or for arrays that are a mix of precurved and straight types.
Brainstem superior olivary-complex neurons are exquisitely sensitive to interaural-difference cues for sound localization. Because these neurons rely on interaurally place-of-stimulation-matched inputs, interaural insertion-depth or scalar-location differences for BI-CI users could cause interaural place-of-stimulation mismatch that impairs binaural abilities.
Insertion depths and scalar locations were calculated from temporal-bone computed-tomography scans for 107 BI-CI users (27 Advanced Bionics, 62 Cochlear, 18 MED-EL).
Median interaural insertion-depth mismatch was 23.4 degrees or 1.3 mm. Mismatch in the estimated clinically relevant range expected to impair binaural processing (>75 degrees or 3 mm) occurred for 13 to 19% of electrode pairs overall, and for at least three electrode pairs for 23 to 37% of subjects. There was a significant three-way interaction between insertion depth, scalar location, and array type. Interaural insertion-depth mismatch was largest for apical electrodes, for electrode pairs in two different scala, and for arrays that were both-precurved.
Average BI-CI interaural insertion-depth mismatch was small; however, large interaural insertion-depth mismatch-with the potential to degrade spatial hearing-occurred frequently enough to warrant attention. For new BICI users, improved surgical techniques to avoid interaural insertion-depth and scalar mismatch are recommended. For existing BI-CI users with interaural insertion-depth mismatch, interaural alignment of clinical frequency tables might reduce negative spatial-hearing consequences.
由于不同的数组放置或特性，双侧人工耳蜗植入（BI-CI）使用者将存在一系列的耳间插入深度不匹配。对于位于顶点或外鼓室的电极，或者对于混合了预弯曲和直型的数组，不匹配程度将更大。
脑干上橄榄复合体神经元对声音定位的耳间差异线索非常敏感。由于这些神经元依赖于耳间刺激匹配的输入，BI-CI 用户的耳间插入深度或标度位置差异可能导致耳间刺激不匹配，从而损害双耳能力。
从 107 名 BI-CI 用户（27 名 Advanced Bionics，62 名 Cochlear，18 名 MED-EL）的颞骨计算机断层扫描中计算插入深度和标度位置。
中位数耳间插入深度不匹配为 23.4 度或 1.3 毫米。在预计会损害双耳处理的临床相关范围内（>75 度或 3 毫米），总体上有 13%至 19%的电极对存在不匹配，而对于 23%至 37%的受试者，至少有三个电极对存在不匹配。插入深度、标度位置和数组类型之间存在显著的三向相互作用。顶点电极的耳间插入深度不匹配最大，对于处于两个不同标度的电极对，以及同时具有预弯曲的数组，不匹配程度最大。
平均 BI-CI 耳间插入深度不匹配较小；然而，足够频繁地出现了大的耳间插入深度不匹配，有可能降低空间听力。对于新的 BICI 用户，建议采用改进的手术技术来避免耳间插入深度和标度不匹配。对于存在耳间插入深度不匹配的现有 BI-CI 用户，临床频率表的耳间对准可能会降低空间听力的负面影响。
