12．Posterior circulation：血流再建術および脳動脈瘤

（12）Revascularisation and Aneurysms of the Posterior Circulation

Ⅰ．はじめに

　2006年にこの連載を始めてから7年，今回で12回目になる．思えばZürich大学にProf. Krayenbühl, Prof. Yaşargilの後任として赴任し，脳神経外科職員の応援，協力を得て，無事2007年5月に任を終え定年退官したが，さらに長い年月が経った．〈Personal view and historical backgrounds〉との副題にあるように，本連載は主に経験した症例について文献と照らし合わせての記述考察である．始めがあれば終わりがあるという常に従って，最近の第9～11回ではもやもや病，PET scan⁴³⁾，グリオーマなどについてをテーマに選んだ．第1回がEC-IC bypassであったが，今回はposterior circulation EC-IC bypassを主題として，それに第3回で論じたanterior circulation動脈瘤のテーマを補足するためにposterior circulationの動脈瘤を付加して，「posterior circulationの血管障害」をテーマにして区切りをつけることを思い立った．私の在任時，座位での後頭蓋窩の手術がTh5より上方の脊髄脊椎手術を含めると1/3以上を占めていた^38,42)事実を考え合わせると，連載を締めくくるテーマとしては適材であると考える．

This is the last article, namely, the twelfth topic, in the series “personal view and historical backgrounds of operative neurosurgery.” In this article, revascularisation and aneurysms of the posterior circulation are thematized. As an example for classic posterior circulation EC-IC bypass, a case of basilar stenosis is presented. The stenosis turned out to occlusion by good patency of the STA-SCA bypass, and although it initially showed clinical improvement, it manifested as severe pontine infarction several months later. Considerations on such malignant conversion are discussed together with probable prevention methods.

　Other revascularisation methods involving the supracerebellar transtentorial approach（SCTTA), namely, OA-SCA or OA-PCA bypass in the sitting position, are presented and their advantages and disadvantages are discussed.

　As for posterior circulation aneurysms, the role of SEAC and its advantages for treating basilar bifurcation aneurysms are presented and discussed. SCTTA and SAHE approach are presented as special approaches for other PCA aneurysms, and their advantages of getting the parent artery P2 for P2-P3 junction aneurysm in the latter was emphasized.

　The advantage of a sitting position for revascularisation or aneurysm surgeries, cleanliness of the operative field in cases of premature rupture or clipping procedure, and through the bush of lower cranial nerves are also discussed.

　

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