豚鼠耳蜗电图变化与体温影响的关系

背景体温对脑干听觉诱发电位有显著影响,其波潜伏期是反映体温影响突触传递和神经纤维传导的客观灵敏指标.耳蜗电图波的起源有待明确,体温对耳蜗电图的影响有待探讨.目的观察体温对耳蜗电图的影响效应,为明确耳蜗电图波的起源及指导其临床应用提供重要实验依据.设计随机区组设计.材料实验于2002-07/09在暨南大学医学院生理学教研室进行.取成年豚鼠40只,随机分为体温降低组和体温升高组两组,每组20只.干预采用体表物理降温或升温法逐步降低或升高豚鼠体温,体温变化率控制在每5～10min降低或升高1℃.体温每变化1℃测试1次脑干听觉诱发电位和耳蜗电图.主要观察指标脑干听觉诱发电位和耳蜗电图的波峰潜伏期与波峰间潜伏期.结果37只豚鼠进入结果分析.①随体温逐步降低(36～25℃)或逐步升高(36～42℃),脑干听觉诱发电位的Ⅰ,Ⅱ,Ⅲ,Ⅳ波波峰潜伏期和Ⅰ～Ⅳ波波峰间潜伏期逐渐延长或缩短,体温越低或越高,延长或缩短越显著;耳蜗电图的N1,N2,N3波波峰潜伏期和N1～N3波波峰间潜伏期同样也随体温降低或升高而逐渐延长或缩短,体温越低或越高,延长或缩短越显著.②随体温变化,代表脑干中枢传递时间的脑干听觉诱发电位的Ⅰ～Ⅳ波波峰间潜伏期的延长总值和缩短总值明显大于代表外周传导时间的Ⅰ波波峰潜伏期的变化值,且源自脑干中枢的Ⅱ,Ⅲ,Ⅳ波的波峰潜伏期的延长总值和缩短总值明显大于源自听神经的Ⅰ波波峰潜伏期的变化值,耳蜗电图的N1～N3波波峰间潜伏期的延长总值和缩短总值也明显大于代表外周传导时间的N1波波峰潜伏期的变化值,N2,N3波波峰潜伏期的延长总值和缩短总值也明显大于源自听神经的N1波波峰潜伏期的变化值.结论体温对耳蜗电图的显著影响与脑干听觉诱发电位相似,耳蜗电图的N2,N3波较源自听神经的N1波有更高位的神经起源.

Association between the changes of electrocochleogram and the effects of body temperature in guinea pigs

BACKGROUND: Body temperature has significant effects on brainstem auditory evoked potentials (BAEP). The wave latency of BAEP is the sensitive and objective index for reflecting the effects of body temperature on the synaptic transmission and nerve fiber conduction. The wave origin of electrocochleogram (ECochG) and the effects of body temperature on it need to be probed into to further define its wave origin so as to guide its clinical application.OBJECTIVE: To observe the effects of body temperature on ECochG and provide important basis for further defining its wave origin and guiding its clinical application.DESIGN: A randomized block design.MATERIALS: This study was performed in the Department of Physiology, Medical College of Jinan University between July and September 2002. Forty adult guinea pigs were randomly divided into hypothermia group (n=20) and hyperthermia group (n=20).INTERVENTIONS: The body temperature of the guinea pigs was decreased or increased step by step with their body contacted with physical method. and the changed rate of body temperature was kept as decreased or increased by 1 ℃ every 5-10 minutes. BAEP and ECochG were detected when the body temperature was changed by 1 ℃.MAIN OUTCOME MEASURES: The PL and IPL of BAEP and ECochG were observed.RESULTS: Finally, 37 guinea pigs were involved in the analysis of relonged as the body temperature was decreased step by step from 36 ℃ to 25 ℃, and shortened as the body temperature was increased gradually from 36 ℃ to 42 ℃. The PL and Ⅰ-Ⅳ IPL prolonged or shortened more significantly with the temperature changed. The PL of wave N1, N2 and N3 and N1-N3 IPL of ECochG also prolonged or shortened as the body temperature perature,the total prolonged and shortened values of Ⅰ -Ⅳ IPL representing the central transmission time of brainstem were much greater than that of wave Ⅰ PL representing the peripheral conduction time, .and the total prolonged and shortened values of thePL of wave Ⅱ , Ⅲ and Ⅳ originating from the brainstem centers were much greater than that of wave Ⅰ originating fromthe auditory nerve. The total prolonged and shortened values of N1-N3 IPL were greater than that of wave N1 PL representing the peripheral conduction time, and the total prolonged and shortened values of the PL of wave N2 and N3 were much greater than that of wave N1 originating from the auditorynerve.CONCLUSION: The significant effects of body temperature on ECochG are similar to those of BAEP, and the origin of wave N2 and N3 of ECochG is higher than that of wave N1 that originates from the auditory nerve.