To confirm the usefulness of N18 and other SEP components of medullary origin for the diagnosis of brain death

1.在接受资助的三年中，我们收集了大约100名脑死亡或昏迷患者的约140份SEP和ABR记录以及临床体征。结果，在所有脑死亡的记录中，中位数SEP中的N18被丢失，而在昏迷但不是脑死亡的记录中，它被保留了近90%。也就是说，N18对于检测剩余的脑干功能具有完美的特异性和非常高的敏感性(高于保存了约80%昏迷记录的ABR)。我们成功地跟踪了8例脑突出症患者从昏迷到脑死亡的过程。反映中脑功能的体征，如光反射和眼头反射首先消失，其次是反映脑桥功能的体征，如角膜反射和ABR中的波III。最后，在短时间内出现咳嗽反射和咽反射消失、自主呼吸停止、血压骤降和N18丢失，判定为脑死亡。N18的消失与这些反映延髓功能的信号一起消失的事实进一步支持了我们的观点，即N18是由位于延髓的楔状核产生的。延髓对维持生命功能起着最重要的作用，目前尚无神经生理学或其他方法能客观评价延髓的功能。ABR只能评估脑桥和中脑功能。本研究建立了N18作为髓功能的第一个客观指标。N18的广泛临床应用必将提高脑死亡诊断的可靠性。其他相关研究包括：脑死亡后残留的类P13电位的起源(Sonoo)，P9的起源(Mochizuki和Sonoo)，以及确定中位SEP刺激强度的最佳方法(Fukuda和Sonoo)。

1. We collected around 140 recordings of SEP and ABR together with clinical signs from around 100 brain-dead or comatous patients during the 3 years we accepted the grants. As a result, N18 in median SEPs was lost in all the brain-dead recordings whereas it was preserved in nearly 90% of comatous but not brain-dead recordings. Namely, N18 had perfect specificity and very high sensitivity (higher than ABR which was preserved for about 80% of comatous recordings) for detecting the remaining brainstem function.2. We managed to follow the course progressing from coma to brain-death in 8 patients having brain herniation. Signs reflecting midbrain function such as light reflex and oculocephalic reflex were first lost, those reflecting pontine function such as corneal reflex and wave III in ABR followed. Lastly, loss of cough reflex and pharyngeal reflex, cease of spontaneous respiration, sudden fall of blood pressure and loss of N18 occurred within a short time and brain-death was judged to be established. The fact that N18 disappeared concomitantly with these signs reflecting medullary functions further supported our opinion that N18 is generated by the cuneate nucleus located in the medulla oblongata.3. There has been no neurophysiological or other method which can objectively evaluate the function of medulla oblongata which plays the most important role for maintaining the vital functions. ABR can evaluate only pontine and midbrain functions. The present investigation established N18 as the first objective indicator for the medullary function. Wide clinical application of N18 must increase the reliablity of the diagnose is of brain death.4. Other related researches performed include: the origin of the P13-like potential which remains after brain death (by Sonoo), the origin of P9 (by Mochizuki and Sonoo) and the best method to determine the stimulus intensity in median SEPs (by Fukuda and Sonoo).