Ethanol infiltration into the stapedio-vestibular joint reduces low-frequency vibration of the ossicular chain and round window membrane in the guinea pig

Abstract

Background: The synovial stapedio-vestibular joint (SVJ), which serves as a bridge between the stape and oval window, can be found in guinea pigs and most human adults. Unlike the fibrous SVJs in other animals, the contribution of the synovial SVJ to middle ear sound transmission remains unknown.

Aims/objectives: In this study, we investigate whether sclerosis of the synovial SVJ contributes to frequency-dependent vibration of the ossicular chain and round window membrane (RWM).

Materials and methods: A model of SVJ sclerosis model was established in the guinea pig using 75% ethanol. A laser Doppler vibrometer was then used to measure vibrations of the RWM and the long process of the incus (LPI) under pure tone sound stimulations of 0.25–16 kHz. The influence of SVJ sclerosis was analysed by comparing structural vibration displacement between the normal and sclerosis groups.

Results: Both LPI and RWM vibrations significantly decreased at low frequencies after infiltration of ethanol, which caused SVJ sclerosis.

Conclusions: SVJ sclerosis reduces low-frequency vibration of the ossicular chain and RWM in the guinea pig, which indicates that the synovial SVJ is vital to low-frequency sound transmission in the middle ear.

Significance: Providing useful data for further research regarding middle ear biomechanics.

Chinese abstract

背景：滑膜镫骨前庭关节（SVJ）是连接镫骨和卵圆窗的桥梁, 发现于豚鼠和大多数成人。与其他动物的纤维状SVJ不同, 滑膜SVJ对中耳声音传播的作用尚不清楚。

目的：在本研究中, 我们研究滑膜SVJ硬化是否导致听骨链和圆窗膜（RWM）的频率依赖性振动。

材料与方法：用75%乙醇建立豚鼠SVJ硬化模型。然后使用激光多普勒振动计测量RWM的振动和在0.25-16kHz纯音声刺激下砧骨长突（LPI）的振动。通过比较正常组和硬化组的结构振动位移, 分析了SVJ硬化的影响。

结果：乙醇浸润后, LPI和RWM低频振动均明显降低, 导致SVJ硬化。

结论：SVJ硬化可降低豚鼠听骨链和RWM的低频振动, 说明滑膜SVJ对中耳低频传声至关重要。

意义：为中耳生物力学的进一步研究提供有用的资料。

Keywords:

• ethanol
• guinea pigs
• incus
• middle ear
• round window membrane
• sclerosis
• stapedio-vestibular joint
• stapes
• vibration

Disclosure statement

None of the authors have potential conflicts of interest to disclose.

Additional information

Funding

This study was funded by the Shanghai Committee of Science and Technology, China (No. 10ZR1405800) and the National Natural Science Foundation of China [NSFC, No. 81570934 and 81771014].