ABSTRACT
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.