兔脑温升高时听觉诱发电位的变化

CHANGES OF AUDITORY EVOKED POTENTIALS IN RABBITS DURING HIGH BRAIN TEMPERATURE

兔单侧颈总动脉血体外加温灌流可选择性地升高脑温。在脑温升高3℃过程中,听觉脑干诱发电位成分Ⅰ的峰潜伏期无明显改变,成分Ⅱ～Ⅵ及听觉中潜伏期诱发电位成分Pa的峰潜伏期则逐渐缩短,其中Pa变化最早和最显著;Ⅰ～Ⅲ,Ⅲ～Ⅵ和Ⅵ～Pa峰间期的缩短,以Ⅵ～Pa变化最早、最显著。经脑复温而仍存活的兔,缩短的峰潜伏期可逐渐恢复,当脑复温至加温前水平时,Ⅱ、Ⅴ和Ⅵ峰潜伏期及Ⅲ～Ⅵ峰间期较加温前延长。结果表明,兔脑温升高可使听觉中枢传导径路上各级神经元的传导功能增强,而脑复温时,增强的传导功能逐渐降低,随后,部分神经元的传导功能低于加温前水平。

Brainstem auditory evoked potentials (BAEPs) and middle latency auditory evoked potentials (MAEPs) were recorded in adult rabbits subjected to right carotid artery bypass through which the brain temperature was gradually changed. Durhig increase in brain temperature by 3℃ , with the exception of wave Ⅰ , the latencies of all components of BAEPs and MAEPs decreased. The latencies of earlier waves decreased less significantly than those of the later waves. The change of latency of wave Pa was most significant. The peak-to-peak latencies of Ⅰ -Ⅲ, Ⅲ-Ⅵ decreased, and Ⅵ -Pa decreased most significantly. When the temperature of the brain returned to its initial level, the latencies of waves Ⅱ , Ⅴ, Ⅵ and peak-to-peak latencies of Ⅲ-Ⅵ increased. The results indicated that during increase in brain temperature in rabbits by 3℃, the central conduction velocity of auditory neurons increased. With restoring the brain temperature to its initial level, the increased conduction velocity also returned to the initial level and decreased to lower than the initial level in certain neurons.