思春期発症A1部動脈瘤破裂の1例：診断上の課題と長期経過

A ruptured A1 segment aneurysm in an adolescent patient：diagnostic challenges and long-term clinical course

前大脳動脈近位部（A1）動脈瘤は全脳動脈瘤の1～2％と報告され，まれな部位である^1）。多くは穿通枝分岐部に発生し，治療時には穿通枝温存が課題となる^2）。従来は直達術が主に行われてきたが，近年は血管内治療の報告もみられる^3）。また，A1には解離性動脈瘤の報告もあり^4），嚢状動脈瘤か解離性動脈瘤かの判別が治療方針に影響する。今回我々は，若年発症で長期にわたり再破裂を繰り返したA1動脈瘤を経験し，解離性病変であったことを確認したため報告する。

Aneurysms of the proximal anterior cerebral artery（A1）are rare and may present as either saccular or dissecting types. We report a young patient with recurrent rupture of an A1 aneurysm and describe the long-term clinical course. A 13-year-old boy presented with subarachnoid hemorrhage（SAH）, but no aneurysm was detected. At age 16, rerupture occurred, and coil embolization was performed for a left A1 saccular aneurysm. After nine years, SAH recurred at age 25. Intraoperative findings revealed a dissecting aneurysm, and trapping was performed. Differentiating between saccular and dissecting aneurysms is challenging, and direct surgery may be required to ensure long-term outcomes in selected young patients.