Experimental Study on Hearing Impairment in Acoustic Neuromas

研究耳蜗血流量（CBF）与耳蜗电活动之间的关系，以更好地了解耳蜗循环功能不全，耳蜗循环功能不全被认为是听力损失的一个原因。人工耳蜗循环功能不全实验动物模型人工耳蜗循环功能不全实验动物模型采用窒息、NO2缺氧、AICA梗阻模型。窒息和NO2缺氧期间的全身血压（BP）变化与CBF的变化明显相关。然而，在窒息初期，尽管血压下降，但CBF没有变化。这些差异似乎与脑血流的自动调节有关。窒息与NO2缺氧对第八神经复合动作电位的影响无显著差异。使用AICA阻塞的实验数据不足以提供CBF减少时AP变化的信息。然而，数据表明CBF减少率越高，AP.2的消失率越高。类固醇激素和低温对耳蜗循环功能不全的影响虽然未观察到全身类固醇激素后脑血流的变化，但全身类固醇激素后N1 （AP）潜伏期的恢复时间缩短。低温实验也得到了类似的结果。基于这些结果的分析，我们得出结论，耳蜗循环功能不全时耳蜗活动的可逆性可以通过类固醇和低温治疗得到改善。

The relationship between cochlear blood flow (CBF) and cochlear electrical activity was investigated to better understand cochlear circulatory insufficiency, which is considered to be a cause of hearing loss acoustic neuroma.1. Experimental animal models for cochlear circulatory insufficiencyExperimental animal models for cochlear circulatory insufficiency were made by asphyxia, NO2 anoxia and obstruction of AICA.Changes in systemic blood pressure (BP) during asphyxia and NO2 anoxia were clearly associated with changes in CBF. At the initial stage of asphyxia, however, CBF did not change in spite of the decrease in BP. These discrepancies appeared to be related to autoregulation of CBF. There was no difference in the change in compound action potential of the eighth nerve (AP) between asphyxia and NO2 anoxia.Data from the experiment using AICA obstruction were insufficient to provide information on changes in AP as CBF decreased. However, the data indicated that the higher the CBF reduction rate, the higher the disappearing rate of AP.2. Effects of steroid hormone and hypothermia on cochlear circulatory insufficiencyAlthough changes in CBF following systemic administration of steroid hormone were not clearly observed, the recovery time of N1 (AP) latency became shorter with systemic administration of steroid hormone. Similar results were obtained with hypothermia. Based on the analysis of these results, we concluded that the reversibility of the cochlear activity in cochlear circulatory insufficiency could be improved by the administration of steroid and hypothermia.