听觉诱发电位在重症脑功能检测中的应用

Clinical applications of auditory evoked potentials in ICU

在重症患者中,诱发电位是实时检测神经功能状态、信号传导和感觉信息次级处理进程的重要工具.长潜伏期诱发电位对周围和中枢性感觉传导通路的信号传递进行检测,代表丘脑-皮层和皮层间的复杂信号处理过程.通过重症患者的诱发电位检测,可以了解脑功能状态并进行预后分析.脑干听觉诱发电位（短潜伏期）和听觉刺激的事件相关电位（长潜伏期听觉诱发电位）在重症患者中主要用于：缺氧缺血或创伤性昏迷患者的预后分析、监测神经系统功能好转或衰退、确认脑死亡的发生.短潜伏期脑干诱发电位中Ⅴ波的缺失或分化不良与不良预后相关,但Ⅴ波存在的患者预后不定.近来的研究发现,长潜伏期诱发电位,尤其是听觉刺激错误匹配模式中皮层电位存在及其波幅良好是患者良好预后的特异性指标.对于婴幼儿患者,短潜伏期诱发电位除用于脑损伤的监测外,还用来检测重症患者听觉受累的情况.

In critically ill patients,evoked potential（EP） testing is an important tool for measuring neurologic function,signal transmission,and secondary processing of sensory information in real time.EP potential measures conduction along the peripheral and central sensory pathways with longer-latency potentials representing more complex thalamocortical and intracortical processing.In critically ill patients with limited neurologic exams,EP provides a window into brain function and the potential for recovery of consciousness.Brainstem auditory EP and cortical event-related potentials are most commonly used in ICU.The primary indications for EP in critically ill patients are prognostication in anoxic-ischemic or traumatic coma,monitoring for neurologic improvement or decline,and confirmation of brain death.Historically,EP has been regarded as a negative prognostic test,that is,the absence of cortical potentials are associated with poor outcomes while the presence cortical potentials are prognostically indeterminate.In recent studies,the presence of middle-latency and long-latency potentials as well as the amplitude of cortical potentials is more specific for good outcomes.Event-related potentials,particularly mismatch negativity of complex auditory patterns,is emerging as an important positive prognostic test in patients under comatose.In infants,other than anoxic-ischemic or traumatic brain injury,brainstem auditory is also widely used in premature baby,bilirubin encephalopathy and detection of possible hearing loss.