Round window and promontory movements during bone conduction with different middle ear conditions in Thiel embalmed specimens

Abstract

Background: Thiel conservation is mainly based on a watery solution of salts. We have shown that bone conduction (BC) evokes motion in normal middle ears of Thiel embalmed specimens that is comparable to the motion for other cadaveric models.

Aims/Objectives: We evaluated whether promontory and round window (RW) motion identifies differences in BC transmission for different middle ear conditions.

Methods: We investigated the conditions of mobile ossicle chain, cement-fixed stapes and stapedectomy in seven ears. A retroauricular bone anchored hearing system provided BC stimulation. The motions of the promontory and the RW were measured using single point laser Doppler vibrometer (LDV, HLV1000, Polytec).

Results: The averaged differences between the conditions were small for RW motion and for promontory motion. However, for RW motion we found differences of more than one standard deviation at some frequencies. These differences in RW motion were more apparent when we limited the analysis to three selected specimens.

Conclusions and Significance: Extracochlear measurement of the RW motion with LDV allowed differentiation between BC for different middle ear conditions. These changes could be detected best in a small frequency range in selected specimens. Promontory motion could not be used to differentiate between different conditions of the middle ear.

ABBREVIATIONS: LDV: laser Doppler vibrometry; Prom: cochlear promontory; RW: round window; ST: stapes; TM: tympanic membrane; VProm: velocity of the promontory; VRW: velocity of the round window

Chinese abstract

背景：泰尔（Thiel）防护主要基于盐的水溶液。我们已经证明骨传导（BC）会引起Thiel防腐标本的正常中耳的动态, 这与其它尸体模型的动态相当。

目的：我们评估了鼓岬和圆窗（RW）动态是否识别不同中耳条件下BC传导的差异。

方法：我们研究了7只耳朵的移动小骨链、水泥固定镫骨和镫骨切除术的情况。耳后骨锚定听力系统提供BC刺激。使用单点激光多普勒振动计（LDV, HLV1000, Polytec）测量鼓岬和圆窗的动态。

结果：圆窗运动和鼓岬运动的条件之间的平均差异很小。然而, 对于圆窗动态, 我们发现在某些频率上存在多于一个标准差的差异。当我们将分析局限于三个选定样本时, 圆窗动态的这些差异更为明显。

结论和意义：使用LDV进行圆窗动态的耳蜗外测量可以区分BC的不同中耳条件。在所选样本中, 可以在较小的频率范围内最佳地检测到这些变化。鼓岬动态不能用于区分中耳的不同条件。

Keywords:

• Bone conduction
• middle ear manipulation
• anatomic whole head specimens

Acknowledgment

We thank Professor John Allum for editing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by University of Bern & Swiss Commission for Technology and Innovation (CTI), No. 12593.