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

1.我们收集了大约140记录SEP和ABR连同临床症状，从大约100脑死亡或昏迷的患者在3年期间，我们接受的赠款。结果，在所有脑死亡记录中，中位数SEP中的N18丢失，而在近90%的昏迷但非脑死亡记录中保留。即N18对脑干剩余功能检测具有良好的特异性和极高的敏感性（高于ABR，后者能保留约80%的昏迷记录）.我们追踪了8例脑疝患者从昏迷到脑死亡的过程。ABR中反映中脑功能的体征如光反射、眼头反射等最先消失，反映桥脑功能的体征如角膜反射、波III等次之。最后，咳嗽反射和咽反射消失、自主呼吸停止、血压突然下降和N18丢失在短时间内发生，判定为脑死亡。N18的消失与这些反映延髓功能的体征同时出现，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。延髓是维持生命功能最重要的部位，目前尚无神经生理学或其他方法能客观评价其功能。ABR仅能评价脑桥和中脑功能。本研究确定N18为延髓功能的第一个客观指标。N18在临床上的广泛应用必将提高脑死亡诊断的可靠性.其他相关研究包括：脑死亡后保留的P13样电位的起源（由Sonoo），P9的起源（由Mochizuki和Sonoo）以及确定中位SEP刺激强度的最佳方法（由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).