Effects of round window dexamethasone on residual hearing in a guinea pig model of cochlear implantation
Effects of round window dexamethasone on residual hearing in a guinea pig model of cochlear implantation
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DOI：
10.1159/000111780
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发表时间：
2008-01-01
影响因子：
1.6
通讯作者：
O'Leary, Stephen J.
中科院分区：
文献类型：
--
作者：
James, David P.;Eastwood, Hayden;O'Leary, Stephen J.
为了研究电声刺激，我们开发了一种通过耳蜗造口术进行豚鼠耳蜗植入的模型。植入前三十分钟，将载有地塞米松或生理盐水的透明质酸/羧甲基纤维素珠放置在圆窗膜上。未接受珠子的动物作为对照。在电极插入之前和之后以及 1 周和 4 周后估计纯音听觉脑干反应阈值。进行了选定的耳蜗组织学检查。结果：人工耳蜗植入后24 h耳蜗内可检测到地塞米松。所有动物在手术后立即出现频率阈值升高。植入后 1 周，这些阈值在 2 kHz 及以下完全恢复，并在更高频率下部分恢复。在 32 kHz 频率下，地塞米松的存在对听力具有显着的保护作用，但在较低频率下则不然，这种作用的强度随着时间的推移而增强。在遇到电极插入难以克服的困难植入时，保护效果最好。经过盐水处理的植入耳的植入部位存在持续的异物反应，但经过地塞米松处理的植入耳则没有。结论：术前通过圆窗短期注射地塞米松可以保护人工耳蜗植入过程中的残余听力，尤其是在技术难度较大的手术中。版权所有 (c) 2007 S. Karger AG，巴塞尔。
To study electric acoustic stimulation, we have developed a model of guinea pig cochlear implantation via a cochleostomy. Thirty minutes prior to implantation, a hyaluronic acid/carboxymethylcellulose bead, loaded with either dexamethasone or normal saline, was placed upon the round window membrane. Animals that did not receive beads acted as controls. Pure-tone auditory brainstem response thresholds were estimated before and after electrode insertion, and 1 and 4 weeks later. Selected cochlear histology was performed. Results: Dexamethasone could be detected in the cochlea for 24 h after cochlear implantation. Thresholds were elevated across frequencies in all animals immediately after surgery. These thresholds recovered completely at and below 2 kHz, and partially at higher frequencies by 1 week after implantation. At 32 kHz, but not the lower frequencies, the presence of dexamethasone had a significant protective effect upon hearing, which increased in magnitude over time. The protection was greatest in difficult implantations where an intractable resistance to electrode insertion was met. There was a persistent foreign body reaction at the site of implantation of saline-treated implanted ears but not in the dexamethasone-treated implanted ears. Conclusion: Short-term preoperative delivery of dexamethasone through the round window can protect residual hearing during cochlear implantation, especially during technically difficult surgery. Copyright (c) 2007 S. Karger AG, Basel.