Frijns J H, de Snoo S L, Schoonhoven R
E.N.T. Department, Leiden University Hospital, The Netherlands.
Hear Res. 1995 Jul;87(1-2):170-86. doi: 10.1016/0378-5955(95)00090-q.
In spite of many satisfactory results, the clinical outcome of cochlear implantation is poorly predictable and further insight into the fundamentals of electrical nerve stimulation in this complex geometry is necessary. For this purpose we developed a rotationally symmetric volume conductor model of the implanted cochlea, using the Boundary Element Method (BEM). This configuration mimics the cochlear anatomy more closely than previous, unrolled models. The calculated potential distribution in the cochlea due to stimulating electrodes is combined with a multiple non-linear node model of auditory nerve fibres, which we recently developed. The combined model is used to compute excitation profiles of the auditory nerve for a variety of stimulus levels and electrode positions. The model predicts that the excitation threshold, the spatial selectivity and the dynamic range depend on the exact position of the electrode in the scala tympani. These results are in good agreement with recently published electrical ABR data. It is shown that the use of actively modelled nerve fibres is essential to obtain correct predictions for the biphasic stimuli typically used in cochlear implants and that unrolling the cochlear duct as done in previous models leads to erroneous predictions regarding modiolar stimulation.
尽管人工耳蜗植入取得了许多令人满意的结果，但其临床效果仍难以预测，因此有必要进一步深入了解在这种复杂结构中电刺激神经的基本原理。为此，我们使用边界元法（BEM）开发了植入式耳蜗的旋转对称体积导体模型。这种结构比以前的展开模型更接近耳蜗解剖结构。将刺激电极在耳蜗中产生的计算电位分布与我们最近开发的听觉神经纤维多非线性节点模型相结合。该组合模型用于计算各种刺激水平和电极位置下听觉神经的兴奋分布。该模型预测，兴奋阈值、空间选择性和动态范围取决于电极在鼓阶中的精确位置。这些结果与最近发表的电诱发听性脑干反应（ABR）数据高度一致。结果表明，使用主动建模的神经纤维对于获得人工耳蜗通常使用的双相刺激的正确预测至关重要，并且像以前模型那样展开耳蜗管会导致关于蜗轴刺激的错误预测。
