脳波上のdiffuse α波パターンと局所脳血流量のhyperfrontal pattern

CORRELATION BETWEEN DIFFUSE ALPHA WAVE PATTERN OF EEG AND HYPERFRONTAL PATTERN OF REGIONAL CEREBRAL BLOOD FLOW

　抄録　局所脳血流量（rCBF）と脳波の相関があることはよく知られているが，本論文では脳半球全体としての両者のパターンの相関の有無について検討し，考察した。1）健常人20人，2）脳波上diffuseα波パターンI型を示した14例，3）第2群と年齢をマッチングさせた非diffuse　α波パターンの14例の3群に対して，¹³³Xe内頸動脈注入法によるrCBF測定を行い，rCBFパターンを検討した。健常人のmean CBFは59.2±7.9ml／100g／minで全例にhyperfrontal （HF）パターンを認めた。第2群のmean CBFは47.8±4.9ml／100／minで第1群より有意に（P＜O．OO1）減少していた。14例中9例はHFパターンが消失していた。HFパターンの消失していた9例中2例はmean CBFが正常域にあった。第3群のmean CBFは49.0±3.7ml／100g／minで，第2群とは有意差がなかったが，この群の全例にHFパターンが認められた。第2群のみでHFパターンの消失を認めたことは，diffuse　α波パターンが脳の全般性の軽い機能障害を示すものであり，rCBFのHFパターンの消失もまた脳の全般性の軽い機能障害を反映する所見であることを示唆している。

Reginal cerebral blood flow (rCBF) was mea-sured in three groups ; (1) 20 healhty subjects, (2) 14 patients with diffuse alpha wave pattern of EEG, (3) 14 patients without diffuse alpha wave pattern matching with ages of group 2. In the group 2, one patient with transient ischemic attack, 7 with reversible ischemic neurological deficit, 3 with vertebro-basilar insufficiency, 2 with minor stroke and one with posttraumatic sequelae were selected for rCBF measurements. In the group 3, 3 patients with transient ischemic attack, 7 with reversible ischemic neurological deficit, 2 with vertebro-basilar insufficiency and 2 with minor stroke were selected for rCBF measure-ments. Electroencephalographic analyses were per-formed by using a BERG-Fourier Analyzer, simul-taneously with rCBF measurements. All patients in the group 2 had diffuse alpha wave (generalized continuous simple rhythmic alpha wave-Hori et a1³⁾) pattern of EEG. Regional cerebral blood flow measurement was performed with intracarotid injection method of ¹³³Xe (10mCi) by using the scintillation camera and on-line computer system. ¹³³Xe clearance curve from the whole hemisphere were computed by height over area method. Re-gional value were obtained from brain areas of 6 mm × 6 mm.

Mean hemispheric values were 59.2±7.9 ml/100 g/min in the group 1, 47.8±4.9 ml/100 g/min in the group 2 and 49.0±3.7 ml/100 g/min in the group 3. Although difference between group 2 and 3 was not significant, difference between group 1 and 2 was significant (p<0.001). From analyses of hemispheric pattern of flow distribution (HPFD) , although hyperfrontal pattern was detected in all patients in the group 1 and 3, this pattern was lost in 9 patients in the group 2. Two patients with normal mean hemispheric value were showed "loss of hyperfrontal pattern". Correlation between diffuse alpha wave pattern of EEG and loss of hyperfrontal pattern of rCBF was thought to be significant, because hyperfrontal pattern had been lost only in the group 2. It is considered that diffuse alpha wave pattern represent mild diffuse cerebral dysfunction, and concluded that not only diffuse alpha wave pattern of EEG but also "loss of hyperfrontal pattern" of rCBF represent mild diffuse cerebral dysfunction.