1993 Fiscal Year Final Research Report Summary
Clinical Study on Brain Death by the Nasopharyngeal Lead with the Aid of an Automatic EEG Analysis System
| Project/Area Number |
04670365
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Legal medicine
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| Research Institution | Kansai Medical University |
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Principal Investigator |
OKII Yutaka Kansai Medical University, Department of Legal Medicine, Assistant, 医学部, 助手 (20121915)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Electroencephalogram / Nasopharyngeal Lead / Automatic EEG Analysis System / Brain Death |
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| Research Abstract |
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.
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