3D-rotation angiography上5mm未満の破裂脳動脈瘤の検討

Evaluation of Ruptured Cerebral Aneurysms under 5mm in Size on 3D-rotation Angiography

Ⅰ．はじめに

　EBM（evidence based medicine）に基づく診療行為が重要視されている中，未破裂脳動脈瘤に関しても日本脳ドック学会より無症候性未破裂脳動脈瘤に対するガイドラインが示されている．その中で手術適応としての大きさは5mm前後より大きいものとされているが⁸⁾，実際の臨床の場ではそれよりも小さな破裂脳動脈瘤に遭遇することは決して稀ではない．一方，近年導入されたrotation angiography（RA）によって得られる3D画像により，動脈瘤や周囲血管の三次元情報が提示できるだけでなく，血管径のサイズも容易に測定しうるようになった^3,4,13)．今回，3D-RAにて最大径が5mm未満と計測された破裂脳動脈瘤について，疫学的要素から診断，治療，転帰に至るまで，5mm以上の破裂動脈瘤と比較検討した．

　According to the recent guideline of the Japanese Society for Detection of Asymptomatic Brain Diseases, it should be considered that the operative indication for unruptured cerebral aneurysms is larger than 5 mm, but we have often encountered patients with subarachnoid hemorrhage (SAH) caused by small ruptured cerebral aneurysms. The aim of our study was to evaluate retrospectively the characteristics of ruptured cerebral aneurysms under 5mm in size on 3-dimensional digital rotation angiography (3D-RA). Eighty patients who presented with acute SAH caused by ruptured aneurysms were admitted in our hospital between January 2003 and September 2007. All patients were examined with 3D-RA and divided into two groups by aneurysmal size; group A was under 5mm (N＝18), group B was larger than 5mm (N＝62). Of aneurysms under 5mm, 45% were located in the anterior communicating artery or anterior cerebral artery, 78% were female and 78% were treated with clipping. Clips of mini and/or the slim type were often applied for aneurysmal clipping. 3D-RA images were useful not only in identification of smaller aneurysms, but also in assessing aneurysmal morphology and relationships to neighboring vessels. However, in the cases of small aneurysms, it is necessary to remember that aneurysms become blood blister-shaped or thrombosed. The clipping for the aneurysm should be performed with consideration of choice for clips consisting of various types according to aneurysmal morphology.