Introduction: Widespread use of neuroimaging has led to increased detection of incidental, unruptured cerebral aneursyms. The management of unruptured aneurysms remains controversial. Currently, the need for treatment of an aneurysm is based on morphometric features and the location of lesion, which serve as a crude surrogate for rupture risk. Aspect and size ratios are widely used in clinical practice but tends to have high inter-observer variability. Aneurysm ostium (OA), measured at the level of aneurysm origin from the parent vessel, is a reproducible and easily obtainable metric. Owing to the paucity of existing literature on OA parameters, we investigated the association between these parameters and aneurysmal rupture.
Methods: A retrospective morphometric analysis of saccular intracranial aneurysms(IA) was conducted on 99 subjects. Using Vascular Modeling Toolkit, 3D reconstruction of aneurysm was rendered and morphological calculations made with the aid of MATLAB coding and AView, an image-based clinical computational tool. The aneurysm size, maximum length of aneurysm(MLA), IA neck, circumference of aneurysm ostia(OAC) and maximum length of aneurysm ostium(MLOA) was obtained. Patient-specific factors like hypertension, diabetes, hyperlipidemia, smoking, h/o SAH was noted along with rupture status at presentation.
Results: 99 IAs (anterior= 80, posterior= 19) were analyzed in the study, including 28 ruptured aneursyms. The mean subject age was 60.4±12.4 years. Using Spearman correlation, MLA was strongly correlated with OAC (r=0.72) and MLOA (r=0.70). On non-parametric analyses, lower OAC was observed in ruptured aneurysms versus unruptured aneurysm (11.5 mm2 v/s 15.0 mm2; p=0.004). Additionally, MLOA and perpendicular to MLOA calculated in ostial plane was significantly lower in ruptured aneurysms (p=0.008; p=0.002, respectively). Size or maximum length of IA did not differ between these two groups.
Conclusions: Aneurysm ostial parameters are easily reproducible measures that correlate with the rupture status in saccular aneurysms and maybe superior surrogates to IA neck measurements.
Patient Care: Finding the balance between the risk of therapeutic intervention and protection against spontaneous aneurysm rupture continues to be a challenge for neurosurgeons. The alteration of surface morphometry in ruptured aneurysms adds to the complexity of retrospective analysis of these parameters. To understand the natural history of a given aneurysm and predict its rupture risk, we need to identify a reproducible measure which can be implemented with relative ease in surgical practice. The aneurysm ostia (OA) measured at the origin of aneurysm from the parent vessel, can be valuable in this context. Our study demonstrates a high degree of correlation of OA measurements with the aneurysm size and with the rupture status of aneurysms retrospectively. This may be a superior surrogate measure than neck measurements, which are subject to high inter-rater variability.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) understand the risk factors associated with cerebral aneurysm rupture 2) Understand the role of aneurysmal ostia as a surrogate measure of analyzing rupture status.