痙攣発作の生理学的機構における先端樹状突起の関与に関する実験的検討

DESTRUCTION OF APICAL DENDRITIC LAYERS IN PENICILLIN-INDUCED CORTICAL EPILEPTIC FOCUS

　抄録　難治性皮質焦点性てんかんにたいしては，今日においても皮質焦点切除術が有効な治療法の1つとされているが，その焦点が重要な皮質中枢領域に存在するとき，かかる手術の適応はない。われわれは，外傷性難治性皮質焦点性てんかんで，運動領野を含む脳表浅層凝固術を行ったところ，運動機能は全く損われず，7年間にわたり完全に痙攣発作が抑制できている1例を経験している。そこで，犬の運動領野に限局性ペニシリン焦点を作成し，先端樹状突起の破壊を行い，棘波抑制効果について実験的検討を行った。内包を刺激し脳表で得られる逆向性皮質反応は3つの陰性波（I,II,III波）がみられ，このうちIII波は先端樹状突起に由来すると考えられ，これが焦点の作成部位の決定と脳表破壊深度の判定に有用であった。ペニシリン焦点が形成された部では，皮質脳波で棘波が認められ，前述のIII波は陽性波となり，次に皮質浅層（I，II層）の破壊でIII波は消失した。III波の消失と同時に棘波も消褪することが確かめられた。これは，Hocher—manら（1980）の実験結果と一致し，難治性皮質焦点性てんかんの新しい手術法として臨床応用できる可能性が示唆されたが，今後なお多くの検討すべき問題を残している。

It has been generally accepted that topectomy is a choice of treatment for patients who have an intractable cortical epileptic focus. However, the surgery is not indicated in the cases whose focus is functionally involved in the vital cortical re-gions. We have experienced a case of intractable traumatic cortical epilepsy, in which the patient underwent cortical surface coagulation on his mo-tor cortex during the dissection of his wide-spread durocortical adhesion. Subsequently, his epileptic attacks have been abolished completely for over 7 years without motor deficit. It is the purpose of this work to confirm experimentally that destruction of apical dendrites on the epileptic focus may prevent occurrence of abnormal spike epileptic discharges without vital neuronal deficit.

Fifty dogs were used in this study. In normal dogs, the antidromic cortical response, after stimu-lation of the internal capsule, showed three pre-dominant negative waves axonal (the first), cortical neuronal (the second) and apical dendritic poten-tials (the third) by surface recordings.

Upon creation of the penicillin-induced cortical epileptic focus, spike discharges appeared on the corticogram, and the third wave of the antidromic cortical response shifted from negative to positive.

Selected destruction of the dendrites, in the first and the second cortical layers, in the area of the epileptic focus brought about disappearance of the third wave, to isopotentially, and a marked inhibition or complete disappearance of spikes on the corticograms.

The possibility exists, as been suggested by our experiment, to clinically apply this method as a treatment for intractable cortical epilepsy with foci in the functionally vital regions, although there are yet many problems to be solved.