側頭部皮質焦点発作と発作後回復期に及ぼす脳梁正中離断の影響

EFFECTS OF CALLOSAL BI-SECTION ON TEMPORAL CORTICAL SEIZURE AND POSTICTAL REFRACTORY PERIOD IN KINDLED CATS

　抄録　1回の全身けいれん発作が，後続する同発作の再現を抑制する期間を発作後回復期（PRP）とよぶ。さきに，キンドリングモデルによるPRP研究の実験条件を明らかにし，それが単なる疲労現象によるものではなく，より積極的な発作抑制機序がが関与すると推論した。この点をさらに明確にするために，また脳正中離断が発作に及ぼす影響を発作後抑制現象の側から今回の研究を行つた。側頭部皮質キンドリングネコを用いて脳梁と海馬交連の正中離断を行い，全身けいれんとPRPの変化を検討した。その結果はつぎのようである。1）正中離断群のキンドリングでは，左右非対称の全身けいれんにとどまつた。2）同群の後発射，発作後平坦脳波期および律動性高振幅徐波期は、いずれも刺激側半球にに限局していた。発作後の行動抑制期は対照群に比べ短縮していた。3）発作後の脳波抑制期は対照群と同様であつたが，PRPは明らかに短縮した。以上の成積から，脳正中離断が発作前強度を軽滅するが，PRPが短縮して次回の発作が起こりやすくなること，PRP中，側頭部皮質焦点に対して，脳梁と海馬交連を介した反対側半球からの抑制が及んでいることを考察した。

Effects of midline be-section including corpus callosum and hippocampal commissure on the kindled generalized convulsion and postictal refractotory period (PRP) were examined in temporal cortical kindled cats. Time latency for re-appearance of generalized convulsion after the initial generalized convulsion was designated as a PRP arbitrarily in this experiment. Six repeated electrical stimulation at afterdischarge threshold intensity with one hour interval was performed, and EEG was recorded during PRP test session. Following results were obtained: 1) Kindled generalized convulsion in the split brain cats was characterized by asymmetrical or hemi-convulsion with lateralized afterdischarge in the stimulatedhemisphere, 2) EEG silence and monorhythmic 2.5-3 cps high voltage slow activity in the split brain cats did not differ, rather prolonged than the control group in duration, but such postictal EEG changes were lateralized only in the stimu-lated hemisphere. Behavioral suppression was reduced markedly by midline bi-section, as com-pared with intact control, 3) In the PRP session of the split brain cats, the initially induced hemi-convulsion appeared with lateralized active afterdischarge lasting for 76.8 sec in the stimu-lated hemisphere. It was followed by the postictal EEG change as mentioned above in the stimulated hemisphere. In spite of such full-blown ictal events in the stimulated hemisphere, PRP was shorter (within 2 hrs) in the split brain cats than the control cats (more than 4 hrs).

It is concluded that midline bi-section including corpus callosum and hippocampal commissure not only modify the pattern and duration of kindled generalized convulsion, but markedly reduce a sei-zure intensity reflected by shortening of postictal behavioral suppression and PRP.