A Correlation Study Between Rupture Of Aneurysm And The Morphous Of Intracranial Aneurysm, The Structure Change Of Intracranial Aneurysm Wall

Background and Purpose:Despite technical advances in endovascular and microsurgical treatment, patients with aneurysmal still have a high mortality and morbidity rate. To improve the treatment results in patients with aneurysms, we must better understand the pathophysiology of cerebral aneurysms and the mechanisms leading to their rupture. And to make clear the indication of surgical treatment, we had better know the relevance of rupture of aneurysm and the morphous of aneurysm. Therefore, we studied the pathological and morphological differences between unruptured and ruptured aneurysms.Objective and methods:Ruptured (n=66) and unruptured (n=32) aneurysms were obtained at surgery. The morphous of aneurysm was measured in 3D-CTA. The size of aneurysm was scored from 1 (tiny) to 4 (giantism). We could also get the other length of the aneurysm to describe the morphous of aneurysm. The aneurysmal endothelium was scored from 0 (normal) to 5 (complete disruption) by using a electron microscope. The aneurysmal wall was evaluated by immunohistochemical methods. The wall structure was scored from 1 (dense collagen and rich, smooth muscle cells) to 5 (hyaline-like structure). The degree of inflammatory cell invasion into the wall was also scored from 0 (very few cells) to 3 (many cells).Results:There was no difference between the size of ruptured aneurysms and unruptured aneurysms (Mann-Whitney U test,P=0.993). Ruptured aneurysms manifested significant globular morphous (1.5483±0.3101 versus 0.8900±0.3722, T test, P=0.000), significant endothelial damage (Mann-Whitney U test, P=0.000), significant structural changes of the wall (Mann-Whitney U test, P=0.000), and significant inflammatory cell invasion(Mann-Whitney U test, P=0.000) compared with unruptured aneurysms. There was a significant correlation between the score for wall structure and the score for inflammatory cell invasion (r=0.790;Spearman rank correlation test, P<0.01). So did the globular morphous and the score for endothelial damage (r=0.939;Spearman rank correlation test, P<0.01), the globular morphous and the score for wall structure (r=0.891;Spearman rank correlation test, P<0.01),the globular morphous and the score for inflammatory cell invasion (r=0.813;Spearman rank correlation test, P<0.01),the score for endothelial damage and the score for wall structure (r=0.897;Spearman rank correlation test, P<0.01),the score for endothelial damage and the score for inflammatory cell invasion (r=0.822;Spearman rank correlation test, P<0.01).The pathophysiology of several symptomatic unruptured aneurysms was similar to that of ruptured aneurysms.Conclusions:There was no difference between the size of ruptured aneurysms and unruptured aneurysms but we conclude that the morphous and pathophysiology of unruptured and ruptured aneurysms are different. The wall of ruptured aneurysms was found to be fragile, possibly because macrophage infiltration into the aneurismal wall resulted in loss of smooth muscle cells and in degradation of matrix proteins.