Experimental Study on Hearing Impairment in Acoustic Neuromas

为了更好地了解耳蜗血流量(CBF)与耳蜗电活动之间的关系，以更好地了解耳蜗血循环障碍，该疾病被认为是听力损失的一个原因听神经瘤。以窒息、NO2缺氧、AICA梗阻等方法制作耳蜗性循环障碍动物模型。窒息、NO2缺氧期全身血压变化与脑血流量变化明显相关。然而，在窒息初期，尽管血压下降，但脑血流量并没有改变。这些差异似乎与CBF的自动调节有关。窒息和NO2缺氧组第八神经复合动作电位变化无差异，AICA阻断实验数据不足以提供脑血流量下降时第八神经复合动作电位变化的信息。然而，数据表明，CBF减少率越高，AP2的消失率越高。类固醇激素和亚低温对耳蜗血循环障碍的影响全身应用类固醇激素后，脑血流量变化不明显，但N1(AP)潜伏期恢复时间随全身应用类固醇激素而缩短。低温治疗也得到了类似的结果。通过对上述结果的分析，我们得出结论：应用激素和低温可以改善耳蜗性循环功能不全的耳蜗电活动的可逆性。

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.