Kha H N, Chen B K, Clark G M
Department of Mechanical Engineering, Monash University, Wellington Road, Clayton Victoria 3800 Melbourne, Australia.
J Biomech. 2007;40(12):2796-805. doi: 10.1016/j.jbiomech.2007.01.013. Epub 2007 Apr 3.
Previous experimental studies of insertion of the Nucleus standard straight and the Contour arrays into the scala tympani have reported that the electrode arrays cause damage to various cochlear structures. However, the level of insertion-induced damage by these electrode arrays to cochlear structures (the spiral ligament, the basilar membrane and the osseous spiral lamina) has not been quantified. Although it has been suggested that rotation can overcome this resistance and prevent the basilar membrane from being pierced by the tip of the Nucleus standard straight array, there has not been any attempt to study the relationship between the rotation and the reduction of damage to the basilar membrane. In this study, 3D finite element analyses of insertions of the Nucleus standard straight array and the Contour array into the scala tympani have been undertaken. The perforation of the basilar membrane by the tip of the Nucleus standard straight array at the region of 11-14 mm from the round window appears to be compounded by the geometry of the spiral passage of the scala tympani. Anti-clockwise rotations between 25 degrees and 90 degrees applied at the basal end of the electrode array (for the right cochlea) were shown to significantly reduce the contact stresses exerted by the tip on the basilar membrane which support the practice of applying small rotation partway through insertion of electrode array to minimize damage to the basilar membrane. Although the Contour array (with its stylet intact) is stiffer than the Nucleus standard straight array, a slight withdrawal of the stylet from the Contour array before insertion was found to significantly reduce damage by the electrode array to the spiral ligament and the basilar membrane.
先前关于将Nucleus标准直电极阵列和Contour电极阵列插入鼓阶的实验研究报告称，电极阵列会对各种耳蜗结构造成损伤。然而，这些电极阵列对耳蜗结构（螺旋韧带、基底膜和骨螺旋板）的插入诱导损伤程度尚未得到量化。尽管有人提出旋转可以克服这种阻力并防止基底膜被Nucleus标准直电极阵列的尖端刺穿，但尚未有人尝试研究旋转与基底膜损伤减少之间的关系。在本研究中，对Nucleus标准直电极阵列和Contour电极阵列插入鼓阶进行了三维有限元分析。在距圆窗11 - 14毫米区域，Nucleus标准直电极阵列的尖端对基底膜的穿孔似乎因鼓阶螺旋通道的几何形状而加剧。在电极阵列的基端（针对右耳蜗）施加25度至90度的逆时针旋转被证明可显著降低尖端对基底膜施加的接触应力，这支持了在电极阵列插入过程中进行小角度旋转以尽量减少对基底膜损伤的做法。尽管Contour电极阵列（探针完整）比Nucleus标准直电极阵列更硬，但发现在插入前将Contour电极阵列的探针稍微抽出可显著减少电极阵列对螺旋韧带和基底膜的损伤。
