Perez Ronen, Adelman Cahtia, Sichel Jean Yves, Sohmer Haim
Department of Otolaryngology and Head & Neck Surgery, Shaare Zedek Medical Center, Jerusalem, Israel.
J Basic Clin Physiol Pharmacol. 2009;20(3):197-205. doi: 10.1515/jbcpp.2009.20.3.197.
To assess the effects of occluding the round window on the degree of hearing loss following exposure to broad band noise.
Following opening of the middle ear bulla in both ears of ten sand rats, auditory nerve-brainstem evoked response (ABR) thresholds were determined in each ear separately using an insert earphone. The round window of one ear was then occluded with super-glue. The opposite ear was sham-operated. ABR thresholds were again assessed immediately. The animals were then exposed to 113 dB SPL broad band noise for 12 hours. 24 hours after the round window was occluded, which was 8-10 hours after the end of the noise exposure, ABR thresholds were again determined in each ear. In four control animals, the round window was blocked, but they were not exposed to noise.
Following the noise exposure, the mean ABR threshold elevation in the round window blocked ears (54.5 +/- 5.5 dB) was significantly (p < 0.004) greater than that in the sham-operated ear (40.5 +/- 8.6 dB). In the four control ears, there was no change in ABR threshold 24 hours after the round window was occluded.
Occluding the round window was not accompanied by a threshold elevation, but following noise exposure, the noise induced hearing loss was increased, probably by reducing the efficacy of an inherent protective mechanical mechanism.
评估封闭圆窗对暴露于宽带噪声后听力损失程度的影响。
在十只沙鼠的双耳打开中耳鼓泡后，使用插入式耳机分别测定每只耳朵的听神经-脑干诱发电位（ABR）阈值。然后用强力胶封闭一只耳朵的圆窗。对侧耳朵进行假手术。立即再次评估ABR阈值。然后将动物暴露于113 dB SPL的宽带噪声中12小时。在封闭圆窗24小时后，即噪声暴露结束后8 - 10小时，再次测定每只耳朵的ABR阈值。在四只对照动物中，封闭圆窗，但不暴露于噪声。
噪声暴露后，封闭圆窗耳朵的平均ABR阈值升高（54.5 +/- 5.5 dB）显著（p < 0.004）高于假手术耳朵（40.5 +/- 8.6 dB）。在四只对照耳朵中，封闭圆窗24小时后ABR阈值没有变化。
封闭圆窗并未伴随阈值升高，但在噪声暴露后，噪声诱发的听力损失增加，可能是由于降低了一种内在保护机械机制的功效。
