Prerupture Intracranial Aneurysm Morphology in Predicting Risk of Rupture: A Matched Case-Control Study

Abstract

BACKGROUND Maximal size and other morphological parameters of intracranial aneurysms (IAs) are used when deciding if an IA should be treated prophylactically. These parameters are derived from postrupture morphology. As time and rupture may alter the aneurysm geometry, possible morphological predictors of a rupture should be established in prerupture aneurysms. OBJECTIVE To identify morphological parameters of unruptured IAs associated with later rupture. METHODS Nationwide matched case-control study. Twelve IAs that later ruptured were matched 1:2 with 24 control IAs that remained unruptured during a median follow-up time of 4.5 (interquartile range, 3.7-8.2) yr. Morphological parameters were automatically measured on 3-dimensional models constructed from angiograms obtained at time of diagnosis. Cases and controls were matched by aneurysm location and size, patient age and sex, and the PHASES (population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from another aneurysm, and site of aneurysm) score did not differ between the 2 groups. RESULTS Only inflow angle was significantly different in cases vs controls in univariate analysis (P = .045), and remained significant in multivariable analysis. Maximal size correlated with size ratio in both cases and controls (P = .015 and <.001, respectively). However, maximal size and inflow angle were correlated in cases but not in controls (P = .004. and .87, respectively). CONCLUSION A straighter inflow angle may predispose an aneurysm to changes that further increase risk of rupture. Traditional parameters of aneurysm morphology may be of limited value in predicting IA rupture.

Volumes, outcomes, and complications after surgical versus endovascular treatment of aneurysms in the United States (1993–2015): continued evolution versus steady-state after more than 2 decades of practice

“…A recent Norwegian nationwide case-control study simi- larly found traditional aneurysm morphology parameters could not predict rupture risk. 37 Ruptured and unruptured aneurysms may therefore represent different populations and/or have different pathogeneses, 15 with SAH resulting from aneurysms that rupture a short time after formation, leaving little time for detection and treatment while unruptured. 20,46 This may explain the discrepancy between the observation that most aneurysms presenting with rupture are small (< 7 mm), whereas similarly sized unruptured aneurysms appear to have a low risk of rupture.…”

Survey of European neurosurgeons’ management of unruptured intracranial aneurysms: inconsistent practice and organization

“…Relying too much on aneurysm size may thus cause overtreatment of large but benign aneurysms, and undertreatment of small but dangerous ones. In addition to patient factors, treatment decisions can be supported by aneurysm factors such as morphology and hemodynamics [2,[16][17][18], and magnetic resonance vessel wall imaging [19,20].…”

Weighted gene co-expression network analysis identified six hub genes associated with rupture of intracranial aneurysms

“…This life-threatening clinical condition has an acute mortality rate of approximately 50% [5,6]. Despite considerable advances in therapy for IAs, SAH remains a highly lethal condition which is associated with a high socioeconomic burden [7][8][9]. Thus, an ability to identify IAs which have a high risk of rupture and provide timely preventive treatment may be key to the successful management of IAs.…”

“…To predict IA rupture, researchers have studied aneurysmal hemodynamics [10,11], aneurysmal morphology and location [8], genetics [12], and other factors (e.g., cigarette smoking, hypertension, and positive family history for SAH) [13]. Only inflow angle was identified as a significant predictor of rupture according to morphological parameters [8]. However, aneurysm wall inflammation has also been shown to play a pivotal role in aneurysm growth and rupture [2,3,14].…”

“…Two scoring systems have been established to evaluate the risk of rupture and to guide treatment. These include the PHASES (population, hypertension, age, size of aneurysm, earlier SAH from another aneurysm, and site of aneurysm) system and the UIATS (unruptured IA treatment score) system [8,15,16]. However, standardized management of unruptured IAs remains controversial, as risks of prophylactic treatment must be weighed against possible risk of rupture for individual aneurysms [17].…”