Horner K C, Cazals Y
Inserm U229, Laboratoire d'Audiologie Expérimentale, Hôpital Pellegrin, Bordeaux, France.
Hear Res. 1990 Apr;45(1-2):145-50. doi: 10.1016/0378-5955(90)90190-z.
Most current theories regarding the inner ear pathology of Menières disease assume that there is an augmentation of the endolymphatic pressure due to the presence of hydrops. In this study normal hearing pigmented guinea pigs were employed to investigate the effect of increased endolymphatic pressure on the compound action potential (CAP) audiogram. All animals were implanted with an electrode on the round window and the CAP audiogram was determined prior to further surgery. The endolymphatic canal was then visualised by a posterior fossa intra-dural surgical approach. A hole was pierced in the canal and a cannula inserted. The CAP audiogram was again determined before, and at frequent intervals after, the application of hydrostatic pressure (0.5-1 cm Hg). A similar sequence of CAP sensitivity losses was observed within 2 h for 0.5 cm Hg or 15 min for 1 cm Hg. There was at first a very high frequency loss, followed by a very low frequency loss and finally a mid frequency sensitivity loss rendered the audiogram flat and lying around 50 dB sound pressure level. Given that the first characteristic index for experimental hydrops is a low frequency loss the present data suggest that an increase in endolymphatic pressure, as in these experiments, is likely to be a rather late pathological feature of hydrops. Indeed we have shown that a high frequency loss develops at a second phase during the evolution of hydrops.
目前大多数关于梅尼埃病内耳病理学的理论认为，由于存在积水，内淋巴压力会升高。在本研究中，使用听力正常的有色豚鼠来研究内淋巴压力升高对复合动作电位（CAP）听力图的影响。所有动物均在圆窗植入电极，并在进一步手术前测定CAP听力图。然后通过后颅窝硬膜内手术方法观察内淋巴管。在管上穿孔并插入套管。在施加静水压力（0.5 - 1厘米汞柱）之前和之后的频繁间隔时间测定CAP听力图。对于0.5厘米汞柱，在2小时内观察到类似的CAP敏感性损失序列；对于1厘米汞柱，在15分钟内观察到类似序列。起初是非常高频的损失，接着是非常低频的损失，最后中频敏感性损失使听力图变得平坦，且处于约50分贝声压级附近。鉴于实验性积水的第一个特征指标是低频损失，目前的数据表明，如在这些实验中一样，内淋巴压力升高可能是积水相当晚期的病理特征。事实上，我们已经表明，高频损失在积水演变的第二阶段出现。
