Clinical Study on Brain Death by the Nasopharyngeal Lead with the Aid of an Automatic EEG Analysis System

对于脑死亡的判断，脑干脑电(EEG)是否呈平坦线是非常重要的。因此，我尝试用鼻咽导联的方法，不仅从头皮表面，而且从非常接近脑干基底面的鼻咽壁记录脑电。头皮脑电电极按国际联合会10/20电极系统分别放置于仰卧位受试者的左侧、右侧顶区、颞区和枕区。鼻咽脑电AgCl-电极针头也插入外鼻腔上壁。在耳垂放置参比电极，用参比蒙太奇记录脑电。采用全自动脑电分析系统对头皮和鼻咽部脑电进行分析。(1)研究健康受试者头皮和鼻咽部脑电的差异。结果发现，在鼻咽部脑电中观察到的慢波成分较多，但α成分较少。在光刺激(频率：5赫兹，光强：0.6J)作用下，头皮脑电的α波减少，而角波成分增加，而鼻咽部脑电则无明显变化。对因头皮脑电平坦化和听性脑干反应丧失而被临床推定为脑死亡的患者，探讨头皮和鼻咽脑电之间的关系。所有患者头皮脑电的等效电位均小于健康志愿者，而鼻咽脑电的等效电压均在正常人的分布范围内。

For the judgment of brain death, it is important to determine whether the brain-stem electroencephalogram (EEG) shows flat line or not. I have thus attempted to record EEG not only from the scalp surface but also from the nasopharyngeal wall quite close to the basal surface of brain stem by the nasopharyngeal lead method. The electrodes for the scalp EEG were placed on the right and left sides each of parietal, temporal and occipital regions of the subjects at supine position according to the 10/20 Electorode System of International Federation. AgCl-electorode needle for the nasopharyngeal EEG was also inserted into upper wall of the external nasal cavity. Reference electrodes were placed on the ear lobes and the EEG was recorded by reference montage. Both the scalp and nasopharyngeal EEGs were analyzed using Automatic EEG Analysis System.(1)The difference between the scalp and nasopharyngeal EEGs of the healthy subjects was investigated. It was found that the components of slow waves like delta and theta were observed more but the alpha component was less in the nasopharyngeal EEG than in the scalp EEG.By the photic stimulus (frequency : 5 Hz, strength of light : 0.6J), a decrease of alpha and an increase of theta occurred in the scalp EEG while there no specific changes of them in tha nasopharyngeal EEG.Consequently, the nasopharyngeal EEG was quite different from tha scalp EEG, and was thus expected to reflect the brain stem EEG.(2)The relationship between the scalp and nasopharyngeal EEGs was investigated from the patients who were clinically presumed brain death because of bothe flat-line scalp EEG and loss of auditory brain-stem response. The equivalent electric potentials in the scalp EEG from these patients were smaller than those of the healthy volunteers, but those in the nasopharyngeal EEG from all the patients showed low voltage within the range of distribution in normal subjects.