植入地塞米松洗脱型耳蜗内电极阵列后电极阻抗的长期稳定化

文献信息

中文摘要

背景： 通过植入药物洗脱型耳蜗内电极阵列进行局部类固醇递送，是改善人工耳蜗植入者术后结局的一种新兴策略。已证明地塞米松（DEX）等皮质类固醇可有效减少纤维化组织的形成并最小化电极阻抗。然而，该方法在临床前植入模型中的获益因所施加电刺激的程度和所测量阻抗的类型而异。在使用每日电刺激以模拟人类临床情景的情况下，类固醇洗脱型阵列已被证明有助于在5周内维持稳定的四点电极阻抗。在此，我们检查了在延长至15周的时间内植入药物洗脱型耳蜗内阵列并进行每日电刺激后的纤维化和阻抗。方法：成年豚鼠双侧植入完全可植入的DEX洗脱型阵列（右耳）和标准非洗脱型阵列（左耳），并在每日电刺激前后评估电极阻抗。结果：在存在DEX洗脱型阵列的情况下，四点阻抗在研究期间保持稳定，而在存在标准阵列的情况下则显著增加。对跨阻抗矩阵的评估还显示，DEX洗脱型阵列中的阻抗测量值始终较低。与此同时，植入类固醇洗脱型阵列的耳蜗中纤维化组织（尤其是疏松纤维组织）水平较低，并且四点阻抗与纤维化程度之间存在相关性。结论：这项延长研究的结果支持将四点阻抗作为局部纤维化的指标，并支持地塞米松在耳蜗内持续释放对组织-电极界面有益的重要性。

英文摘要

Local steroid delivery via implantation of drug-eluting intracochlear electrode arrays is an emergent strategy for improving postoperative outcomes in cochlear implant recipients. Corticosteroids like dexamethasone (DEX) have been shown effective in reducing formation of fibrotic tissue and minimising electrode impedance. However, the benefits of this approach differ in preclinical implant models with the extent of electrical stimulation applied and the type of impedance measured. Where daily electrical stimulation is used to model human clinical scenarios, steroid-eluting arrays have been shown beneficial in maintaining stable four-point electrode impedance over the course of 5 weeks. Here we examine fibrosis and impedance after implantation of a drug-eluting intracochlear array and daily electrical stimulation over an extended period of 15 weeks. Adult guinea pigs were bilaterally implanted with a fully implantable DEX-eluting array (right ear) and a standard non-eluting array (left ear), with electrode impedance assessed before and after daily electrical stimulation. Four-point impedance remained stable for the duration of the study in the presence of a DEX-eluting array, whilst significantly increasing in the presence of a standard array. Assessment of a trans-impedance matrix also revealed consistently lower impedance measures in the DEX-eluting array. This was accompanied by lower levels of fibrotic tissue (particularly loose fibrous tissue) in cochleae implanted with a steroid-eluting array, and correlation between four-point impedance and the extent of fibrosis. The outcome of this extended study supports four-point impedance as an indicator of local fibrosis, and the importance of sustained intracochlear release of dexamethasone to benefit the tissue-electrode interface.