保存方法对同一标本中耳力学的影响。
Effect of conservation method on ear mechanics for the same specimen.
机构信息
Department of ENT, University Basel Hospital, Hebelstrasse 10, 4031 Basel, Switzerland; Department of ENT, Kantonsspital Aarau, Switzerland.
Department of ENT, Spital Münsingen and University of Bern, Switzerland.
出版信息
Hear Res. 2021 Mar 1;401:108152. doi: 10.1016/j.heares.2020.108152. Epub 2020 Dec 16.
BACKGROUND AND AIMS
As an alternative to fresh temporal bones, Thiel conserved specimens can be used in the study of ear mechanics. Conserved temporal bones do not decay, permit long-term experiments and overcome problems with limited access to fresh (frozen) temporal bones. Air conduction motion of the tympanic membrane (TM), stapes (ST) and round window (RW) in Thiel specimens is similar to that of fresh specimens according to reports in the literature. Our study compares this motion directly before and after conservation for the same specimens.
METHODS
The magnitude of motion of TM, ST and RW elicited by acoustic stimulation via the external auditory canal was measured using single point laser Doppler vibrometry (LDV) accessed through a posterior tympanotomy. For the initial measurements (10 ears), fresh frozen whole heads were thawed for at least 24 h. Afterwards, the entire whole heads were embalmed according to the Thiel embalming method and measurements were repeated 3 and 12 months later.
RESULTS
The magnitudes of TM, ST and RW motion before and after Thiel conservation differed maximally 10 dB on average. A significant increase in TM motion was observed at low frequencies only after long term conservation (12 months). ST motions decreased significantly between 161 and 5300 Hz after 3 months of Thiel conservation. Over the same time period RW motions decreased significantly between 100 and 161 Hz and 489-788 Hz. The ST and RW motions across all measured frequencies were lower after 3 months by 5.7 dB and 7.1 dB, respectively, without further changes after 12 months of conservation. The mean phase shift between ST and RW motion was only 2.1° for frequencies below 450 Hz.
DISCUSSION AND CONCLUSION
Thiel embalming changes motion of TM after long term conservation. ST and RW motion changed mainly after short term conservation. The phase shifts close to 180° between ST and RW motion indicates that the cochlea was still filled with liquid without air bubbles. The results show that Thiel conserved specimens can be used as an alternative model to fresh frozen preparations with some limitations when studying mechanics of the normal human ear, for example, in implant design.
背景与目的
作为新鲜颞骨的替代物，Thiel 保存标本可用于研究耳力学。保存标本不会腐烂，允许进行长期实验，并克服了新鲜（冷冻）颞骨获取有限的问题。文献报道称，Thiel 标本中的鼓膜（TM）、镫骨（ST）和圆窗（RW）的空气传导运动与新鲜标本相似。我们的研究直接比较了同一标本在保存前后的运动情况。
方法
通过经外耳道进行声学刺激，使用单点激光多普勒测振仪（LDV）测量 TM、ST 和 RW 的运动幅度，LDV 通过后鼓室切开术进入。对于初始测量（10 耳），将新鲜冷冻的整个头部解冻至少 24 小时。之后，根据 Thiel 保存方法对整个头部进行防腐处理，并在 3 个月和 12 个月后重复测量。
结果
Thiel 保存前后 TM、ST 和 RW 运动的幅度差异最大为 10dB 左右。仅在长期保存（12 个月）后才观察到低频 TM 运动显著增加。在 3 个月的 Thiel 保存后，ST 运动在 161Hz 至 5300Hz 之间显著降低。在同一时间段内，RW 运动在 100Hz 至 161Hz 和 489Hz 至 788Hz 之间显著降低。在 3 个月后，ST 和 RW 运动在所有测量频率下的幅度分别降低了 5.7dB 和 7.1dB，在 12 个月的保存后没有进一步变化。在低于 450Hz 的频率下，ST 和 RW 运动之间的平均相位差仅为 2.1°。
讨论与结论
Thiel 保存长期保存后会改变 TM 的运动。ST 和 RW 运动主要在短期保存后发生变化。ST 和 RW 运动之间接近 180°的相位差表明，耳蜗内仍充满液体而没有气泡。结果表明，Thiel 保存标本可作为新鲜冷冻标本的替代模型，用于研究正常人类耳的力学，例如在植入物设计中，但存在一些限制。
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