急性脳症脳波の自己回帰過程における情報処理活動と臨床神経学的所見との相関

THE CORRELATION BETWEEN CLINICAL STAGING AND BIOINFORMATION AMOUNT ON THE AUTOREGRESSIVE PROCESSES OF EEGs IN ACUTE ENCEPHALOPATHY and REYE'S SYNDROME

I．はじめに

　急性脳症は小児特有の予後不良な疾患であるが，その本態は今日のところなお明らかでない。したがつて，その治療は早期に神経学的所見をチェックし，脳浮腫の早期治療に全力を注ぐことがその予後を支配するといつてよい。

　すでに著者（小川，1971）^5）は一定の神経学的諸徴候をもととして，本症における臨床像の病時期的分類を試み発表した。そのなかで，脳波所見は有力な情報を提供するが，視察的観察ではある程度の限度があり，より詳細な情報がのぞまれた。

The autoregressive powerspectrum and their com-ponent analyses of 36 electroencephalograms of 10 children suffering from acute encephalopathy were studied. The data were recorded on the analog tapes, and the 20 second artifact free segment of records was digitalized at 50 samples/sec. The aotoregressive powerspectrum and their component were calculated by the method of Sato and Ono (1975, 1976) with a using the minicomputer PDP 11/40. The component consisted of several second degree oscillatory activities of alpha, delta, theta, beta rhythms and the first degree monosillatory activity of delta wave. The second degree activity was an oscillatory process characterized by frequency of oscillation, the damping coefficient (ζ) to indicate decay of amplitude with respect time and the mutual information amount.

The results were as follows:

1. The various characteristics of component were analyzed in terms of prognosis, with resulting the correlation between information amount, damping coefficient and course of the disease.

2. The information amount of alpha rhythm increased during the course of disease, whereas that of delta rhythm decreased. The damping coefficient was apparently inversely related to the information amount.

3. Differential grades of severity could be dis-tinguisched from alpha/delta ratio (the percentage of information amount of alpha rhythm to that of delta). In mild forms of illness the ratio normalized rapidly; when the ratio showed a high value on the early hospital day and was reduced during the course of disease, a bad prognosis were considered.

4. To provide the necessary of early treatment, it would be important to conduct repeated alpha/ delta ratio of information amount during early phase of the disease.

5. According to Freeman's hypothesis "K-set of neural mass action" (1975), the first order auto-regressive activity of monoscillatory process may be given as KO, KI-sets and the second order activity of oscillatory process as a KII-set. The mechanism of bioinformation processing on the neurophy-siological disturbance caused by acute encephalo-pathy were discussed.