Irregular Shape of Intracranial Aneurysm Indicates Rupture Risk Irrespective of Size in a Population-Based Cohort

Abstract

Larger size increased the risk of rupture also in the Japanese (Unruptured Cerebral Aneurysm Study [UCAS]) and Finnish natural history studies. 5,7 Observational studies, however, demonstrate that a significant portion of those sIAs that ruptured did so Background and Purpose-Size and shape of saccular intracranial aneurysms (sIA) reflect the condition of the sIA wall and were risk factors for rupture in previous follow-up studies. We investigated how well size or shape identify ruptureprone sIAs. Methods-In a population-based registry, we investigated the characteristics of ruptured sIAs treated in a single neurosurgical center . In addition to univariate analysis, logistic regression was used in multivariate analysis, and sensitivity and specificity of size or shape were calculated using receiver operating characteristic curves. Results-Ruptured sIAs were on average larger than unruptured sIAs (median, 7 versus 4 mm; P<0.000), but location and patient background affected the size at rupture. Of the ruptured sIAs, 38% were smaller than 7 mm and 18% were smaller than 4 mm. Of those sIAs that had ruptured at a small (<7 mm) size, 87% had an irregular shape. In multivariate analysis, irregular shape had the strongest association with presentation as ruptured sIA (odds ratio, 7.1; 95% confidence interval, 6.0-8.3), with better sensitivity (91%) and specificity (76%), in contrast to smoking (odds ratio, 0.7; 95% confidence interval, 0.6-0.9; sensitivity, 28%; specificity 57%) and Population, Hypertension, Age, Size of sIA, Earlier SAH from another sIA, Site of sIA score (odds ratio, 1.5; 95% confidence interval, 1.4-1.6). Conclusions-Irregular

Differences in Morphologic and Hemodynamic Characteristics for “PHASES-Based” Intracranial Aneurysm Locations

“…28 Recently, the radiological identification of aneurysm irregularities or the presence of daughter aneurysms was independently associated with aneurysm rupture in a Finnish cohort. 29 Our objective quantification of surface irregularities is supported by the findings of previous work by our group that found UI was a significant risk factor for rupture in our cross-sectional database. 5, 7 …”

Morphological and numerical assessment of intracranial aneurysms ruptures risk

“…This form of aneurysm was described by Weir in 1987 [28]. In recent years, more and more researchers [4,8,11,16,22,23] point to the fact that ruptured aneurysms have irregular shape. From the mechanical point of view, wall of an aneurysm with inhomogeneities can have an inhomogeneous stress field, and structure of the flow inside such aneurysms becomes unstable and inhomogeneous.…”

“…Moreover, it was noted that irregular shape of aneurysm dome indicates a high risk of rupture, regardless of its size [11,22]. The appearance of irregularities on the surface of aneurysm dome indicates degradation of its wall and a possible thrombosis of its lumen [22].…”

“…The appearance of irregularities on the surface of aneurysm dome indicates degradation of its wall and a possible thrombosis of its lumen [22].…”

“…Moreover, ruptured aneurysms, in contrast to unruptured ones, had more complex structure of blood flow and multiple vortices. This can be explained by the fact that as a rule ruptured aneurysms have inhomogeneous structure of the wall, which assumes the presence of aneurysms in aneurysm (so-called irregular shape) [8,11,22].…”