側副血行路の発達により良好な経過を呈した前大脳動脈解離性動脈瘤の1例

Dissecting Aneurysm of the Anterior Cerebral Artery with Later Development of Collateral Circulation : A Case Report

I．はじめに

　頭蓋内の解離性動脈瘤は椎骨脳底動脈系（以下，VB系）に多く^18），前大脳動脈解離性動脈瘤（以下，ACA-DA）は報告例が23例と稀な疾患である^4-17,22）．このACA-DAは虚血症状で発症することが多く，この場合保存的治療で良好な経過を得ている報告が多い^{1,9,10,13,14,16）}．そのため治療方針として一般的に保存的治療が第1選択となる．しかしながら，保存的治療で進行性あるいは再発性の虚血症状を呈するもの，また進行性解離が認められるものは外科的治療の適応があると考えられており^{15,17，22）}，特に経時的な脳血管撮影による血管動態の確認が必要となる．今回われわれは，脳梗塞で発症したACA-DA症例において，経時的脳血管撮影を行うことにより側副循環の発達を認め良好な経過を呈した症例を経験したので文献的考察を加え報告する．

Intracranial dissecting aneurysm (DA) is much less frequent than berry aneurysm. Such dissection in-volves mostly the vertebral and basilar arteries, followed by the internal carotid and middle cerebral arter-ies. DA of the anterior cerebral artery (ACA) is relatively rare and little is known about its natural De-velopment. Only 23 cases have been reported previously. Our present patient, a 44-year-old man, suddenlydeveloped paresis of the left leg while bathing. Diffusion magnetic resonance imaging indicated an area ofhigh signal intensity in the territory of the ACA. Angiography on clay 3 following onset showed a DA in-volving the left A2 segment. Antiplatelet therapy was administered. Further luminal narrowing in the le-sion was demonstrated by repeat angiography on day 17. Occlusion of the distal A2 segment was demons-trated together with sufficient collateral supply on clay 41. Symptoms resolved completely. DA of the ACA usually presents with ischemic attacks. Its etiology remains uncertain, and its naturalcourse is unclear. Surgical intervention is recommended for patients with intracranial hemorrhage, whilenon surgical therapies have achieved good outcomes in ischemic cases.