Department of Otolaryngology, Istanbul Bahcelievler State Hospital, Istanbul, Turkey.
Department of Otolaryngology, Faculty of Medicine, Beykent University, Istanbul, Turkey.
ORL J Otorhinolaryngol Relat Spec. 2021;83(4):272-279. doi: 10.1159/000513871. Epub 2021 Mar 30.
The aim of the study was to evaluate the association of conductive hearing loss (CHL) with the structural changes in the organ of Corti.
Twenty ears of 10 healthy adult Wistar albino rats were included in the study. The right ears (n = 10) of the animals served as controls (group 1), and no surgical intervention was performed in these ears. A tympanic membrane perforation without annulus removal was performed under operative microscope on the left ears (n = 5) in 5 of 10 animals (group 2). A tympanic membrane perforation with annulus removal was performed under operative microscope on the left ears (n = 5) of the remaining 5 animals (group 3). Auditory brainstem response testing was performed in the animals before the interventions. After 3 months, the animals were sacrificed, their temporal bones were removed, and inner ears were investigated using scanning electron microscopy (SEM). The organ of Corti was evaluated from the cochlear base to apex in the modiolar axis, and the parameters were scored semiquantitatively.
In group 1, the pre- and post-intervention hearing thresholds were similar (p > 0.05). In group 2, a hearing decrease of at least 5 dB was encountered in all test frequencies (p > 0.05). In group 3, at the frequency range of 2-32 kHz, there was a significant hearing loss after 3 months (p < 0.01). After 3 months, the hearing thresholds in group 2 and 3 were higher than group 1 (p < 0.01). The hearing threshold in group 3 was higher than group 2 (p < 0.01). On SEM evaluation, the general cell morphology and stereocilia of the outer hair cells were preserved in all segments of the cochlea in group 1 with a mean SEM score of 0.2. There was segmental degeneration in the general cell morphology and outer hair cells in group 2 with a mean SEM score of 2.2. There was widespread degeneration in the general cell morphology and outer hair cells in group 3 with a mean SEM score of 3.2. The SEM scores of group 2 and 3 were significantly higher than group 1 (p < 0.05). The SEM scores of group 3 were significantly higher than group 2 (p < 0.05).
CHL may be associated with an inner ear damage. The severity of damage appears to be associated with severity and duration of CHL. Early correction of CHL is advocated in order to reverse or prevent progression of the inner ear damage, which will enhance the success rates of hearing restoration surgeries. Subjective differences and compliance of the hearing aid users may be due to the impact of CHL on inner ear structures.
本研究旨在评估传导性听力损失（CHL）与耳蜗结构变化之间的关系。
将 10 只健康成年 Wistar 白化大鼠的 20 只耳朵纳入研究。动物的右耳（n = 10）作为对照组（第 1 组），这些耳朵不进行任何手术干预。在手术显微镜下对 10 只动物中的 5 只（n = 5）的左耳进行鼓膜穿孔但不切除环（第 2 组）。在手术显微镜下对其余 5 只动物（n = 5）的左耳进行鼓膜穿孔伴环切除（第 3 组）。在干预前对动物进行听觉脑干反应测试。3 个月后，处死动物，取出颞骨，使用扫描电子显微镜（SEM）对内耳进行研究。在耳蜗的蜗轴上，从耳蜗基底到顶点对耳蜗进行评估，并对参数进行半定量评分。
第 1 组中，干预前后的听力阈值相似（p > 0.05）。第 2 组中，所有测试频率的听力下降至少 5 dB（p > 0.05）。第 3 组中，在 2-32 kHz 的频率范围内，3 个月后听力明显下降（p < 0.01）。3 个月后，第 2 组和第 3 组的听力阈值高于第 1 组（p < 0.01）。第 3 组的听力阈值高于第 2 组（p < 0.01）。在 SEM 评估中，第 1 组所有耳蜗节段的外毛细胞的一般细胞形态和静纤毛均保持完整，SEM 评分均值为 0.2。第 2 组的一般细胞形态和外毛细胞出现节段性退化，SEM 评分均值为 2.2。第 3 组的一般细胞形态和外毛细胞广泛退化，SEM 评分均值为 3.2。第 2 组和第 3 组的 SEM 评分显著高于第 1 组（p < 0.05）。第 3 组的 SEM 评分显著高于第 2 组（p < 0.05）。
CHL 可能与内耳损伤有关。损伤的严重程度似乎与 CHL 的严重程度和持续时间有关。提倡早期纠正 CHL，以逆转或预防内耳损伤的进展，这将提高听力修复手术的成功率。助听使用者的主观差异和顺应性可能是由于 CHL 对内耳结构的影响。
