Bone conduction hearing in the blockage of oval and/or round windows in cats

Abstract

Background: Simple or non-syndromic types of oval window (OW) or round window (RW) atresia are relatively rare in clinical. Few studies have assessed bone conduction (BC) hearing in OW or RW atresia patients, with some reporting that BC hearing lies within the normal range, whereas others observing impaired BC hearing.

Aims/Objectives: This study explored the effect of blocking the OW and RW during BC in cat models.

Material and Methods: Twenty-four cats were randomly divided into three immobilization groups (OW blockage, RW blockage, and OW + RW blockage) and control group. Each immobilization group also had the initial control state before blockage. Medical adhesive and ear mould glue were used to immobilise the stapes footplate and RW, respectively. Comparisons were made of the auditory brainstem response (ABR) thresholds before and after immobilization for the three immobilization groups during three different stimuli [air conduction (AC) click, BC click, and BC pure tones].

Results: The AC click thresholds increased after immobilisation in three experimental groups compared to the control group (p < .05). The AC click thresholds increased compared to their initial control state after all three immobilization groups (p < .05). With an increase in frequency from 2 to 8 kHz, there was a general decrease in the difference between pre- and post-immobilization BC hearing thresholds in all three immobilization groups. The BC click threshold and BC tone thresholds at 2–4 kHz in both OW blockage and OW + RW blockage groups exceeded those in RW blockage group (p < .05).

Conclusions and Significance: The use of medical adhesive and ear mould glue for the blockages of OW and RW, respectively in cats was feasible. The effect of blocking the OW and RW in BC hearing was larger at low frequencies than high frequencies between 2 and 8 kHz. OW blockage had a greater effect than RW blockage on BC hearing at 2–4 kHz range.

Chinese abstract

背景：单纯型或非综合征型的卵圆窗（OW）或圆窗（RW）闭锁在临床上比较少见。对OW或RW闭锁患者的骨传导（BC）听力进行评估的研究很少。其中一些研究报告BC听力在正常范围内, 而另一些则观察到BC听力受损。

目的：本研究探讨了猫模型中BC期间阻塞OW和RW的效应。

材料与方法：将24只猫随机分为三个固定组（OW阻塞组、RW阻塞组、OW和RW阻塞组）和对照组。各固定组在堵塞前均处于初始控制状态。分别用医用胶和耳模胶固定镫骨踏板和圆窗。比较三个固定组在三种不同刺激?空气传导（AC）点击、BC点击和BC纯音?中固定前后的听觉脑干反应（ABR）阈值。

结果：与对照组相比, 3个实验组在固定后的空气传导点击阈值有所增加（P <0.05）。在所有三个固定组之后, 空气传导点击阈值与初始控制状态相比有所增加（p <0.05）。随着频率从2 kHz增加到8 kHz, 这三个固定组的固定前后BC听力阈值之间的差异普遍降低。OW阻塞组和OW+RW阻塞组的BC点击阈值和BC音调阈值在2-4 kHz时都超过了RW阻塞组的阈值（p <0.05）。

结论和意义：医用胶和耳模胶分别用于猫的OW和RW阻塞是可行的。在2～8kHz之间, 低频率时阻塞OW和RW在骨传导听力方面的影响比高频率时要大。在2-4 kHz范围内, OW阻塞对BC听力的影响大于RW阻塞。

Keywords:

• Cats
• bone conduction
• oval window
• round window
• atresia

Acknowledgments

The authors thank The National Science and Technology Support Program (Grant No.2015BAK31B01) and the Shanghai Committee of Science and Technology (Grant No. 13dz1940902), China.

Disclosure statement

The authors declared no financial relationship with the organization which sponsored the research.