脳底部穿通動脈の側副路としての可能性およびその加齢的変化—脳血管"Moyamoya"病に関連して

THE STUDY ON THE AGING OF THE PERFORATING BRANCHES AND ITS POSSIBILITY OF COLLATERAL PATHWAY : CONCERNING WITH CEREBROVAS-CULAR "MOYAMOYA" DISEASE

緒言

　脳血管写上，脳底部に異常網状血管像を呈する疾患，すなわち脳血管"Moyamoya"病^{1）2）3）4）5）6）}は比較的最近発見された日本人特有の疾患である。すなわち本疾患を一つのentityとして意義あるものと考え鈴木ら^7）がこの6例について報告したのは1963年の第22回日本脳神経外科学会であり，以来本邦諸家の注目を集めるに至つたが，その病因および異常血管網　（以下Moyamoya血管と呼称）発生の根拠，なぜ日本人に多発するか等に関しては議論が多く，今なお多くの解決されない問題が残されている。先ずMoyamoya血管の本態に関してはこれを先天的な血管奇形とするものや血管腫瘍としてとり扱つていたもの，また脳主幹動脈の閉塞に伴う二次的側副血行路とするもの等種々様々の意見が出されてきた。鈴木らは当初よりこのMoyalnoya血管は先天的な奇形や胎生期遺残ではなく，頭蓋内々頸動脈分岐部の慢生進行性の狭窄性病変に伴つて生ずるその付近の脳底部穿通動脈群からなる側副血行路であると主張し，この患者の脳血管撮影に於ける追跡の結果から，これを実証し報告してきた。しかし一方脳底部穿通動脈が確実に脳に於ける重要な側副血行路の一つとなり得るかどうかに関しては記載が少なく不明の点の多い処であつた。また本疾患の臨床像の追究では，頭蓋内々頸動脈分岐部に同じような狭窄や閉塞がみられても小児例および成人例の間ではMoyamoya血管の様相に質量共に明らかな差がみられ，前者では顕著（第1図）であり後者では貧弱（第2図）であつた。またこのMoyamoya血管の経時的観察でも，その変化は前者ではダイナミックな変化を呈するのに対し，後者ではほとんど変化が認められず，その発症，症状に関しても両者間には著しい差が認められる事が判つてきた。そこで，年令によつてこのMoyamoya血管が質的，量的に差異を呈するに至る解剖学的な根拠はあるのであろうか，またMoyaInoya血管の発現を示すに至る脳底部穿通動脈の吻合は実際に存在するものなのか，如何なる形態学的特徴を有するものなのかという疑問が生じた。これらの疑問を解決すべく，先ず脳底部穿通動脈群中，最大枝である中線状体動脈の加令的変化，次にその末梢間に於ける吻合の有無を検討し，最後に急性頭蓋内主要血管結紮実験を剖検脳で行ない，脳血管"Moyamoya"病に於ける小児・成人間のMoyamaya血管様相の差異発現の根拠やその発生要因に関し考察を加えた。

In Cerebrovascular "Moyamoya" Disease, child-ren and adults commonly show different aspects of abnormal net-like vessels (called "Moyamoya" in the following) at the base of the brain. The reason for the difference did not have been clarified yet. In order to explain the reason, this study was done to investigate possibility and morphology of the amastomosis between the perforating branches as well as influence of their aging by means of micro-angiography and/or graphycal reconstruction of serial sections.

(1) Three groups of fetuses, children and adults were subjected to the study of the aging of Aa. corporis striati mediae. The number, course, and shape of vessels, that is, on such items as diverting angle at the middle cerebral artery, smoothness or irregular changing of its course or direction as well as diameter are carefully observed by microangio-graphy. Changes by aging were revealed remark-ably in all of these items. It must be noted that the younger had the more arteries, suggesting easiness of collateral formation.

(2) The existence of anastomosis between the perforating branches with each other, between these vessels and Aa. medullaris were clearly veri-fied by graphycal reconstruction of serial sections. It was also observed that pattern of the anastomosis and caliber of its each anastomosis were changed by aging. From this observation it might be well explained that the "Moyamoya" vessels appeared as collateral pathway based on the perforating branchels and also that in the younger, "Moya-moya" vessels are easily formed than the older.

(3) In acute experiments of occlusion of intra-cranial main arteries and immediate microangiogra-phy of the cadavor brain, "Moyamoya" vessels have never appeared both in fetuses and adults in spite of their morphological difference as mentioned above.

(4) It will be concluded that two factors are necessary for occurrence of "Moyamoya" Disease : One will be above mentioned morphological factor of the perforating branches and the other will be functional factor, that is, chronic and progressive stenotic changes at the carotid fork and acomp-anying post stenotic dilatation and so on.