2012 Volume 40 Issue 4 Pages 223-228
Background: Rupture of cerebral aneurysms results in subarachnoid hemorrhage. We previously reported that bleeding from cerebral aneurysms can arrest from outside, but bleeding from some aneurysms arrests in different ways.
Methods: Between 2007 and 2011, we prospectively investigated mechanisms of spontaneous hemostasis in ruptured aneurysms by histopathological examination on the specimens of the aneurysm wall, including their rupture points harvested after surgical clipping.
Results: Hemostatic mechanisms were investigated in 77 patients with ruptured aneurysms (21 men, 56 women; age range, 34–87 years). Hemostatic patterns were divided into three different patterns depending on the location of clot formation. In 26 aneurysms (34%), the surface of the aneurysm rupture point was sealed from the outside by clot (outside pattern). In 35 aneurysms (45%), thrombus was attached to the rupture point from inside the aneurysm (inside pattern). In 12 (16%) cases, thrombus extended from inside to outside of the rupture point (inside-outside pattern). In a small number of aneurysms (5%), the rupture point was changed to a fibrin wall like a membrane without a distinct thrombus formation (membrane pattern). These hemostatic patterns demonstrated no correlation with clinical profile of the patients, bleb formation, or aneurysm size. Thinning and fragmentation of aneurysm wall were seen predominantly in the inside and inside-outside pattern (p<0.01) as compared to the outside pattern.
Conclusion: Intra-aneurysm thrombus formation was seen in approximately 61% of ruptured aneurysms. This must be kept in mind when ruptured aneurysms are treated surgically.
