Analysis of Morphological Parameters to Differentiate Rupture Status in Anterior Communicating Artery Aneurysms

In contrast to size, the association of morphological characteristics of intracranial aneurysms with rupture has not been established in a systematic manner. We present an analysis of the morphological variables that are associated with rupture in anterior communicating artery aneurysms to determine site-specific risk variables. One hundred and twenty-four anterior communicating artery aneurysms were treated in a single institution from 2005 to 2010, and CT angiograms (CTAs) or rotational angiography from 79 patients (42 ruptured, 37 unruptured) were analyzed. Vascular imaging was evaluated with 3D Slicer© to generate models of the aneurysms and surrounding vasculature. Morphological parameters were examined using univariate and multivariate analysis and included aneurysm volume, aspect ratio, size ratio, distance to bifurcation, aneurysm angle, vessel angle, flow angle, and parent-daughter angle. Multivariate logistic regression revealed that size ratio, flow angle, and parent-daughter angle were associated with aneurysm rupture after adjustment for age, sex, smoking history, and other clinical risk factors. Simple morphological parameters such as size ratio, flow angle, and parent-daughter angle may thus aid in the evaluation of rupture risk of anterior communicating artery aneurysms

Morphological Parameters Associated with Ruptured Posterior Communicating Aneurysms

The rupture risk of unruptured intracranial aneurysms is known to be dependent on the size of the aneurysm. However, the association of morphological characteristics with ruptured aneurysms has not been established in a systematic and location specific manner for the most common aneurysm locations. We evaluated posterior communicating artery (PCoA) aneurysms for morphological parameters associated with aneurysm rupture in that location. CT angiograms were evaluated to generate 3-D models of the aneurysms and surrounding vasculature. Univariate and multivariate analyses were performed to evaluate morphological parameters including aneurysm volume, aspect ratio, size ratio, distance to ICA bifurcation, aneurysm angle, vessel angles, flow angles, and vessel-to-vessel angles. From 2005–2012, 148 PCoA aneurysms were treated in a single institution. Preoperative CTAs from 63 patients (40 ruptured, 23 unruptured) were available and analyzed. Multivariate logistic regression revealed that smaller volume (p = 0.011), larger aneurysm neck diameter (0.048), and shorter ICA bifurcation to aneurysm distance (p = 0.005) were the most strongly associated with aneurysm rupture after adjusting for all other clinical and morphological variables. Multivariate subgroup analysis for patients with visualized PCoA demonstrated that larger neck diameter (p = 0.018) and shorter ICA bifurcation to aneurysm distance (p = 0.011) were significantly associated with rupture. Intracerebral hemorrhage was associated with smaller volume, larger maximum height, and smaller aneurysm angle, in addition to lateral projection, male sex, and lack of hypertension. We found that shorter ICA bifurcation to aneurysm distance is significantly associated with PCoA aneurysm rupture. This is a new physically intuitive parameter that can be measured easily and therefore be readily applied in clinical practice to aid in the evaluation of patients with PCoA aneurysms

Somatic Variants in SVIL in Cerebral Aneurysms

Publisher Copyright: © American Academy of Neurology.Background and ObjectivesWhile somatic mutations have been well-studied in cancer, their roles in other complex traits are much less understood. Our goal is to identify somatic variants that may contribute to the formation of saccular cerebral aneurysms.MethodsWe performed whole-exome sequencing on aneurysm tissues and paired peripheral blood. RNA sequencing and the CRISPR/Cas9 system were then used to perform functional validation of our results.ResultsSomatic variants involved in supervillin (SVIL) or its regulation were found in 17% of aneurysm tissues. In the presence of a mutation in the SVIL gene, the expression level of SVIL was downregulated in the aneurysm tissue compared with normal control vessels. Downstream signaling pathways that were induced by knockdown of SVIL via the CRISPR/Cas9 system in vascular smooth muscle cells (vSMCs) were determined by evaluating changes in gene expression and protein kinase phosphorylation. We found that SVIL regulated the phenotypic modulation of vSMCs to the synthetic phenotype via Krüppel-like factor 4 and platelet-derived growth factor and affected cell migration of vSMCs via the RhoA/ROCK pathway.DiscussionWe propose that somatic variants form a novel mechanism for the development of cerebral aneurysms. Specifically, somatic variants in SVIL result in the phenotypic modulation of vSMCs, which increases the susceptibility to aneurysm formation. This finding suggests a new avenue for the therapeutic intervention and prevention of cerebral aneurysms.Peer reviewe

Hemodynamic Impact of a Spontaneous Cervical Dissection on an Ipsilateral Saccular Aneurysm

The dynamic, hemodynamic impact of a cervical dissection on an ipsilateral, intracranial saccular aneurysm has not been well illustrated. This 45-year-old female was found to have a small, supraclinoid aneurysm ipsilateral to a spontaneous cervical internal carotid artery dissection. With healing of the dissection, the aneurysm appeared to have significantly enlarged. Retrospective review of the magnetic resonance imaging (MRI) at the time of the initial dissection demonstrated thrombus, similar in overall morphology to the angiographic appearance of the "enlarged" aneurysm. As the dissection healed far proximal to the intradural portion of the internal carotid artery, this suggested that the aneurysm was likely a typical, saccular posterior communicating artery aneurysm that had thrombosed and then recanalized secondary to flow changes from the dissection. The aneurysm was coiled uneventfully, in distinction from more complex treatment approaches such as flow diversion or proximal occlusion to treat an enlarging, dissecting pseudoaneurysm. This case illustrates that flow changes from cervical dissections may result in thrombosis of downstream saccular aneurysms. With healing, these aneurysms may recanalize and be misidentified as enlarging dissecting pseudoaneurysms. Review of an MRI from the time of the dissection facilitated the conclusion that the aneurysm was a saccular posterior communicating artery aneurysm, influencing treatment approach

Endovascular coiling of a ruptured basilar apex aneurysm with associated pseudoaneurysm

Acute intracranial pseudoaneurysms secondary to aneurysmal rupture are a rare entity with no clear evidence-based guidelines for treatment to our knowledge. There are numerous examples of successful treatment of pseudoaneurysms both surgically and endovascularly, the latter mainly within the anterior circulation. Risk of pseudoaneurysm rupture in the acute state during endovascular procedures with subsequent difficulty in controlling the bleeding without sacrificing the feeder artery has led to some reservation in using endovascular treatments more broadly. We report a rare case of a 52-year-old-woman who presented with acute subarachnoid hemorrhage and was found to have a ruptured 5 mm x 8 mm bi-lobulated basilar apex aneurysm on CT angiography. Digital subtraction angiography demonstrated an associated anterior pseudoaneurysm that was formed secondary to the aneurysm rupture. The true aneurysm was successfully coiled with careful avoidance of the pseudoaneurysmal sac. Pseudoaneurysms are frequently identified for the first time during digital subtraction angiography. Recognizing their presence is essential for treatment planning. Acute pseudoaneurysms associated with true aneurysmal rupture can be safely and successfully treated by endovascular coiling of the true aneurysm. Care must be taken to avoid manipulation of the pseudoaneurysmal sac during the embolization

Univariate analyses for the morphological parameters measured for ruptured and unruptured ACoA aneurysms.

<p>P value and odds ratios indicate the level of statistical significance that the value of certain variable differs between the ruptured group and unruptured group (p<0.05 is considered statistically significant).</p

Multivariate analysis after adjustment for clinical and morphological risk factors.

<p>A multivariate logistic regression model was constructed to ascertain morphological parameters that were significant predictors of aneurysm rupture, after adjusting for demographic and clinical risk factors. P value and odds ratios indicate the level of statistical significance for certain parameter in the multivariable regression model (p<0.05 is considered statistically significant).</p

Scatter plots depicting the interaction between size ratio and other morphological parameters.

<p>Linear regression analysis for scatter plot of size ratio and aspect ratio yielded an R² value of 0.75 for the ruptured group and 0.74 for the unruptured group (A), suggesting inter-dependency of the two variables. No clear dependency was observed between size ratio and aneurysm angle (B), flow angle (C), or parent-daughter angle (D).</p