Ye Qing, Tillein Jochen, Hartmann Rainer, Gstoettner Wolfgang, Kiefer Jan
Clinic for Otorhinolaryngology, Head and Neck Surgery, Department of Sensory Physiology, Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
Ear Hear. 2007 Jun;28(3):361-9. doi: 10.1097/01.aud.0000261655.30652.62.
Opening of the inner ear during stapes surgery or cochlear implantation may result in trauma to inner ear structures and possible hearing loss. The dual aim of the present study was to evaluate the effectiveness of locally applied Triamcinolon* to protect the inner ear against surgically induced trauma and to exclude possible ototoxic effects.
In an animal model (guinea pig), a corticosteroid (Triamcinolon) was topically applied to the inner ear, either by extracochlear application and diffusion through the round window membrane or by direct intracochlear application via a cochleostomy. Physiological effects of the steroid were investigated by monitoring the hearing of steroid treated animals in comparison to control animals treated with Ringer solution instead of Triamcinolon. Thresholds as well as input/output functions (I/O function) of compound action potentials (CAPs) in response to auditory stimuli were determined before the cochleostomy and at specific intervals up to 4 weeks after application of Triamcinolon.
Extracochlear application of Triamcinolon induced only minor shifts of mean CAP thresholds but significantly increased mean maximal amplitudes of I/O function 14 d after application. No detrimental effects on cochlear function were noted; thus, indicating absence of ototoxicity for extracochlear application in the concentrations used. After the surgical trauma of cochleostomy, CAP thresholds increased by 12.5 dB directly after surgery and by 15.8 dB at day 3. Amplitudes of CAPs diminished. Intracochlear application of Triamcinolon resulted in significantly enhanced recovery of CAP thresholds and amplitudes of I/O function from initial loss over a period of 4 weeks.
From these results, we conclude that extracochlear topical application of Triamcinolon has no ototoxic effect in the concentrations that were used and that intracochlear application supports an increased recovery of cochlear functions after surgical trauma. Furthermore, the results indicate a protective effect of corticosteroids, partially preventing progressive loss of hearing after cochleostomy over a period of 4 weeks. Intracochlear application of Triamcinolon may be useful to prevent hearing loss after surgical intervention on the inner ear; however, clinical safety and efficacy remain to be proven in clinical studies.
镫骨手术或人工耳蜗植入过程中内耳开放可能导致内耳结构损伤及听力损失。本研究的双重目的是评估局部应用曲安奈德*对内耳手术创伤的保护作用，并排除可能的耳毒性作用。
在动物模型（豚鼠）中，通过圆窗膜外耳应用并扩散或经蜗孔直接向耳蜗内应用皮质类固醇（曲安奈德）。通过监测接受类固醇治疗的动物与接受林格液而非曲安奈德治疗的对照动物的听力，研究类固醇的生理效应。在蜗孔切开术前以及应用曲安奈德后特定时间间隔直至4周，测定复合动作电位（CAP）对听觉刺激的阈值以及输入/输出函数（I/O函数）。
耳外应用曲安奈德仅引起平均CAP阈值轻微变化，但在应用后14天显著增加了I/O函数的平均最大振幅。未观察到对耳蜗功能的有害影响；因此，表明在所使用的浓度下耳外应用无耳毒性。蜗孔切开术的手术创伤后，CAP阈值在手术后直接升高12.5 dB，在第3天升高15.8 dB。CAP振幅减小。耳蜗内应用曲安奈德导致CAP阈值和I/O函数振幅在4周内从初始损失显著增强恢复。
从这些结果我们得出结论，在所使用的浓度下耳外局部应用曲安奈德无耳毒性作用，耳蜗内应用支持手术创伤后耳蜗功能的恢复增加。此外，结果表明皮质类固醇具有保护作用，部分预防了蜗孔切开术后4周内听力的逐渐丧失。耳蜗内应用曲安奈德可能有助于预防内耳手术干预后的听力损失；然而，临床安全性和有效性仍有待临床研究证实。
