頭蓋内内頸動脈非分岐部動脈瘤

Unbranched-site Aneurysm of Intracranial Internal Carotid Artery

I．はじめに

　嚢状動脈瘤（sacdllar aneurysm，以下動脈瘤と略す）は，ほとんどの場合動脈分岐部に存在し，動脈分岐と関連なく存在する動脈瘤は，非常に稀である．われわれは，このような動脈瘤を非分岐部動脈瘤（unbranched—site aneurysm）と呼び，頭蓋内内頸動脈に存在した非分岐部動脈瘤8例を報告し，その成因，」三術等について，若干の文献的考察を加えて報告する．

Most intracranial saccular aneurysms arise from the angle between a parent vessel and an arterial branch. Saccular aneurysms without relation to any arterial branch are rare. During the last 24 years, 210 patients with intracranial internal carotid artery (ICA) aneu-rysms were directly operated on at our institution . We found eight saccular aneurysms arising from intracra-nial ICA without relation to any arterial branch. So we call them unbranched-site aneurysms of intracranial ICA, and describe their unique characteristics.

Of the eight cases with unbranched-site aneurysmof intracranial ICA, three were men and five were women. The age ranged from 31 to 61 years with an average age of 48. Seven cases suffered a suharachnoid hemorrhage clue to ruptured unbranched-site aneurysm, and the other case had been admitted to our depart-ment because of accompanying ruptured left internal carotid-posterior communicating aneurysm. All cases of unbranched-site aneurysm presented intraoperative and/ or angiograhic findings of arteriosclerosis, and five of the patients had a past history of hypertension. Of the four unbranched-site aneurysms at the C₂, portion of ICA, two arose from the lateral wall, one arose from the superior wall and the other arose from the infero-lateral wall of ICA. Of the four unbranched-site aneurysms at the C, portion of ICA, three arose from the superior wall and the other arose from the supero-medial wall of ICA. Radical operation was performed in all cases and intraoperative rupture occurred in two cases. It was suggested that arteriosclerotic change in the arterial wall, and local hemodynamic stress played important roles in the development of unbranched-site aneurysms of intracranial ICA.