Newbold Carrie, Mergen Silvana, Richardson Rachael, Seligman Peter, Millard Rodney, Cowan Robert, Shepherd Robert
Cochlear Implants Int. 2014 Jul;15(4):191-9. doi: 10.1179/1754762813Y.0000000050. Epub 2013 Nov 25.
Electrode impedance increases following implantation and undergoes transitory reduction with onset of electrical stimulation. The studies in this paper measured the changes in access resistance and polarization impedance in vivo before and following electrical stimulation, and recorded the time course of these changes.
Impedance measures recorded in (a) four cats following 6 months of cochlear implant use, and (b) three cochlear implant recipients with 1.5-5 years cochlear implant experience.
Both the experimental and clinical data exhibited a reduction in electrode impedance, 20 and 5% respectively, within 15-30 minutes of stimulation onset. The majority of these changes occurred through reduction in polarization impedance. Cessation of stimulation was followed by an equivalent rise in impedance measures within 6-12 hours.
Stimulus-induced reductions in impedance exhibit a rapid onset and are evident in both chronic in vivo models tested, even several years after implantation. Given the impedance changes were dominated by the polarization component, these findings suggest that the electrical stimulation altered the electrode surface rather than the bulk tissue and fluid in the cochlea.
电极阻抗在植入后会增加，并在电刺激开始时经历短暂降低。本文的研究测量了电刺激前后体内接入电阻和极化阻抗的变化，并记录了这些变化的时间进程。
（a）对4只使用人工耳蜗6个月的猫和（b）3名有1.5至5年人工耳蜗使用经验的人工耳蜗接受者记录阻抗测量值。
在刺激开始后的15至30分钟内，实验数据和临床数据均显示电极阻抗分别降低了20%和5%。这些变化大部分是通过极化阻抗的降低发生的。停止刺激后，在6至12小时内阻抗测量值会有同等程度的升高。
刺激引起的阻抗降低起效迅速，在测试的两种慢性体内模型中均很明显，即使在植入数年之后也是如此。鉴于阻抗变化主要由极化成分主导，这些发现表明电刺激改变的是电极表面而非耳蜗中的大块组织和液体。
