Dhanasingh Anandhan, Jolly Claude
MED-EL Medical Electronics GmbH, Innsbruck, Austria.
MED-EL Medical Electronics GmbH, Innsbruck, Austria.
Hear Res. 2017 Dec;356:93-103. doi: 10.1016/j.heares.2017.10.005. Epub 2017 Oct 18.
Cochlear implant electrode arrays are designed with specific characteristics that allow for the preservation of intra-cochlear structures during the insertion process, as well as during explantation. Straight lateral wall (LW) electrode arrays and pre-curved modiolar hugging (MH) electrode arrays are the two types that are commercially available. Although there is a third type of electrode array called the mid-scala (MS), which is positioned in the middle of the scala tympani (ST), and is usually considered as an MH type of electrode. Different lengths of straight LW electrode arrays are currently available which allow for insertion across a range of different sized cochleae; however, due to manufacturing limitations, pre-curved MH electrodes are generally only available to cover the basal turn of the cochlea, while the spiral ganglion cells are distributed in the Rosenthal's canal that extends into 1.75 turns of the cochlea. Both straight LW and pre-curved MH electrodes can cause a certain degree of intra-cochlear trauma, but pre-curved MH electrodes tend to deviate into the scala vestibuli from the scala tympani more often than the straight LW electrodes, resulting in damage to the osseous spiral lamina/spiral ligament which could initiate new bone formation and eventually affect the cochlear implant users' hearing performance. Structural damage to the cochlea could also affect the vestibular function. With pre-curved MH electrodes, higher degrees of trauma are related to the fixed curling geometry of the electrode in relation to the variable coiling pattern of individual cochleae, the orientation of the electrode contacts in relation to the modiolus wall, and how effectively the stylet was handled by the surgeon during the procedure. Wire management, metal density, and the shore hardness of the silicone elastomer all contribute to the stiffness/flexibility of the electrode. It is important to acknowledge the impact of bringing the stimulating contacts closer to the modiolus wall with an MH electrode type in terms of the resultant damage to intra-cochlear structures. The presence of malformed cochleae should be identified and appropriate electrodes should be chosen for each specific cochlea, irrespective of the cochlear implant brand. In order to utilize drug therapy, the cochlea should be free from any trauma.
人工耳蜗电极阵列的设计具有特定特性，以便在插入过程以及取出过程中保护耳蜗内结构。直侧壁（LW）电极阵列和预弯曲蜗轴环抱（MH）电极阵列是两种市面上可买到的类型。虽然还有第三种电极阵列称为中阶（MS），它位于鼓阶（ST）中部，通常被视为MH型电极。目前有不同长度的直LW电极阵列，可用于插入不同大小的一系列耳蜗；然而，由于制造限制，预弯曲MH电极一般仅可用于覆盖耳蜗的基部蜗旋，而螺旋神经节细胞分布在延伸至耳蜗1.75个蜗旋的罗斯纳管中。直LW电极和预弯曲MH电极都会造成一定程度的耳蜗内创伤，但预弯曲MH电极比直LW电极更常从鼓阶偏向前庭阶，导致骨螺旋板/螺旋韧带受损，这可能引发新骨形成并最终影响人工耳蜗使用者的听力表现。耳蜗的结构损伤也可能影响前庭功能。对于预弯曲MH电极，更高程度的创伤与电极相对于个体耳蜗可变蜗旋模式的固定卷曲几何形状、电极触点相对于蜗轴壁的方向以及手术过程中外科医生操作探针的有效性有关。导线管理、金属密度和硅酮弹性体的邵氏硬度都会影响电极的刚度/柔韧性。必须认识到，就对耳蜗内结构造成的损伤而言，使用MH型电极使刺激触点更靠近蜗轴壁所产生的影响。应识别出畸形耳蜗的存在，并为每个特定耳蜗选择合适的电极，而不考虑人工耳蜗品牌。为了利用药物治疗，耳蜗应无任何创伤。
