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Neurological Surgery No Shinkei Geka Volume 29, Issue 10 （October 2001）

Neurological Surgery 脳神経外科 29巻10号（2001年10月発行）

Japanese English

研究

中大脳動脈瘤の流体力学的特徴 Rheological Characteristics of the Aneurysm at the Middle Cerebral Artery Bifurcation 玉野吉範 ¹ , 氏家弘 ¹ , 吉本成香 ² , 堀智勝 ¹ Yoshinori TAMANO ¹ , Hiroshi UJIIE ¹ , Shigeka YOSHIMOTO ² , Tomokatsu HORI ¹ ¹東京女子医科大学脳神経センター脳神経外科 ²東京理科大学機械工学科 ¹Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University ²Department of Mechanical Engineering, Tokyo Science University キーワード： middle cerebral artery aneurysm , bifurcation aneurysm , flow ratio , aspect ratio , area ratio Keyword: middle cerebral artery aneurysm , bifurcation aneurysm , flow ratio , aspect ratio , area ratio pp.921-930

発行日 2001年10月10日 Published Date 2001/10/10

DOI https://doi.org/10.11477/mf.1436902107

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Abstract 文献概要
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I．はじめに

　脳内に発生し，くも膜下出血の原因となる嚢状脳動脈瘤の発生，成長，破裂を促進する因子の1つとして，血行力学的負荷の関与が深く関わっていると考えられる^{2,4,6-9,15,26）}．動脈瘤内の流れに関する研究は数多くあるが^{2,4,10,11,14,15,18-20,22,25，26）}，動脈瘤のgeometryの特徴と流れの相関を定量的に検討したものはない．

　今回われわれは，動脈瘤を有する中大脳動脈分岐部の血管撮影における形態学的特徴について，1）親血管の血管径（M1血管径），2）分岐後血管の血管径（M2血管径），3）neck size，4）動脈瘤の長径等を測定し，これらの測定値からarearatio（M2断面積比），aspect ratio（depth／neckwidth）を求め，脳動脈瘤を有する血管系のgeo-metryの特徴を調べた．このgeometryの検討は中大脳動脈分岐部に，動脈瘤を有さないもの，未破裂動脈瘤を有するもの，破裂動脈瘤を有するものの3グループで行った．

We performed a retrospective clinical study to estimate the morphological index such as aspect ratio(aneurysm depth/neck) and area ratio (ratio of the cross-sectional area of bifurcated arteries) of 64 caseswith saccular aneurysms (ruptured aneurysms: 41, unruptured aneurysms: 23) at the bifurcation of themiddle cerebral artery (MCA) and made a flow visualization study using a flat three dimensional acrylicaneurysm model to define the flow characteristics in conditions similar to those obtained from the clinicalstudy. The mean aspect ratio and area ratio of the ruptured and unruptured aneurysm cases were 2.81±1.45, 2.52±0.91 and 1.56±0.59, 1.73±0.38. These respective values differ statistically. The area ratio of theMCA bifurcation with no aneurysm was 1.25±0.35. This value was also statistically different from the rup-tured aneurysm case. The visualization study was performed changing the neck size and flow ratio into theperipheries to simulate various aspect ratio and flow ratio into peripheries. The results showed that in-treanerysmal flow was definitely influenced by aspect ratio and area ratio. The aspect ratio over 2.0 andarea ratio below 2.0 failed to drive the inflow inside the aneurysms and developed as a stagnant area in thedome side. The morphological index of aspect ratio and area ratio reflected the flow characteristics in theaneurysm and was statistically different in ruptured and unruptured aneurysm cases. The unrupturedaneurysms with an aspect ratio of more than 1.6 and an area ratio of more than 2.0 must be followed up,because of the risk that they might rupture in the near future.