Risk factors for the formation of multiple intracranial aneurysms

Hormonal influences on cerebral aneurysms: unraveling the complex connections

INTRODUCTION

Intracranial aneurysms (IAs) occur in 3-5% of the general population and are characterized by localized structural deterioration of the arterial wall with loss of internal elastic lamina and disruption of the media. The risk of incidence and rupture of aneurysms depends on age, sex, ethnicity, and other different factors, indicating the influence of genetic and environmental factors. When an aneurysm ruptures, there is an estimated 20% mortality rate, along with an added 30-40% morbidity in survivors. The alterations in hormonal levels can influence IAs, while the rupture of an aneurysm can have various impacts on endocrine pathways and affect their outcome.

AREA COVERED

This review explores the reciprocal relationship between endocrinological changes (estrogen, growth hormone, and thyroid hormones) and IAs, as well as the effects of aneurysm ruptures on endocrine fluctuations.

EXPERT OPINION

Based on the data presented in this paper, we recommend further exploration into the influence of hormones on aneurysm formation and rupture. Additionally, we propose conducting endocrine assessments for patients who have experienced a rupture of IAs. Monitoring hormonal changes in patients with IAs could serve as a potential risk factor for rupture, leading to interventions in the approach to managing IAs.

Cavernous carotid aneurysms do not influence the occurrence of upstream ipsilateral aneurysm

OBJECTIVE

Cavernous carotid aneurysms (CCA) comprehend around 5% of all intracranial aneurysms. The main risk factors for an intracranial aneurysm seem not to influence the incidence of CCAs. The aim of this study was to investigate the association of CCAs and the presence of upstream aneurysms.

METHODS

1403 patients, admitted in Hospital das Clinicas de São Paulo, Brazil, from September 2009 to August 2018, enrolled this study. Diagnosis was performed with Digital Subtraction Angiography (DSA). Upstream aneurysm was defined as an intracranial aneurysm on anterior cerebral circulation, ipsilateral to the CCA (if present) or crossing the midline (e.g. anterior communicating artery).

RESULTS

177 individuals were diagnosed with CCA (12.6% of the population), totalizing 225 aneurysms (10% of the total number of aneurysms, 2253). No association was found between CCA and UA (p= .090, OR: 1.323, 95% CI: 0.957-1.828). Studying only patients with CCA, multivariable analysis showed smoking as the only factor associated with UA (p= .010, OR: 0.436, 95% CI: 0.232-0.821).

CONCLUSIONS

Cavernous carotid aneurysms were present in 12% of our population, mostly in female. They seem to be independent of the modifiable risk factors already associated with intracranial aneurysms. A higher frequency of mirror aneurysms was seen in this location. CCA did not influence the presence of ipsilateral and anterior circulation aneurysms.

Unilateral approach for bilateral clipping of posterior communicating artery aneurysms in a hybrid operating room: A technical note

Bilateral posterior communicating (pComm) artery aneurysms represent only 2% of mirror intracranial aneurysms. Usually, these are surgically approached through bilateral craniotomies for clipping. We present the case of a 50-year-old female presenting with headache and horizontal diplopia. Neurological examination revealed a left oculomotor palsy, with no other neurological deficits. Imaging studies revealed bilateral aneurysmatic lesions in both internal carotid arteries (ICA). A conventional left pterional approach was planned in order to treat the symptomatic aneurysm, and, if deemed feasible, a contralateral clipping through the same approach. The procedure was performed in a hybrid operating room (HOR), performing an intraoperative digital subtraction angiography (DSA) and roadmapping assistance during dissection and clipping. Transoperatively, a post-fixed optic chiasm was identified, with a wide interoptic space, which allowed us to perform the contralateral clipping through a unilateral approach. This technique for clipping bilateral pComm aneurysms can be performed when the proper anatomical features are met.

Hyperhomocysteinemia increases the risk of vertebrobasilar dissecting aneurysm among the male Han Chinese population: a retrospective case-control study

OBJECT

Vertebrobasilar dissecting aneurysms (VBDAs) are known to have a poor natural history with high rates of re-bleeding and mortality. There is a strong relation between hyperhomocysteinemia (HHcy) and cerebrovascular disease; we perform a retrospective study within the male of Chinese Han population to explore the association between HHcy and VBDAs.

METHODS

Eighty-eight male patients with VBDA and Eighty-one male control subjects were evaluated for their serum total homocysteine levels. With multiple logistic regression analysis, the association between HHcy and the risk of VBDAs was estimated. Interaction and stratified analyses were conducted according to age, BMI, smoking status, drinking status, and chronic disease histories. The two-piecewise linear regression model examined the threshold effect.

RESULTS

The multivariate logistic regression analyses revealed a significant association between HHcy and VBDAs (odds ratio (OR) = 2.62; 95% confidence interval (CI), 1.02-6.71) after adjusting for classical vascular risk factors. The relationship was stable in all subgroup analysis. The interactive role was not found in the association between HHcy and VBDAs for the potential risk factor.

CONCLUSIONS

In summary, our study provides evidence that HHcy can increases the risk of VBDAs in the male Han Chinese population. Further researches with appropriate study designs including sex differences and aneurysm types are needed to verify this association.

Hemodynamic indicators of the formation of tandem intracranial aneurysm based on a vascular restoration algorithm

Background

Hemodynamic factors are believed to be closely related to IA growth. However, the underlying pathophysiological mechanism that induces the growth sequence in tandem intracranial aneurysms (IAs) remains unclear.

Methods and results

This study involved five patients with tandem IAs. Aneurysm models were reconstructed based on image datasets. A novel vascular restoration algorithm was proposed to generate the hypothetical geometry of the healthy parent vessel before each IA formation in the concatenated structure. Detailed hemodynamic patterns and morphological features were revealed under various growth sequences of tandem IAs to investigate the flow-driven mechanism of IA growth. Potential hemodynamic indicators of IA formation were proposed.

Results

The patient cases were divided into two groups based on the size difference of tandem IAs. In the group with a similar size of tandem IAs, the position of the vortex core was associated with the site of the secondary aneurysm, while in the group with a significant size difference of the IAs, the position with the maximum curvature of the parent vessel plays a significant role in aneurysm formation.

Conclusions

This study preliminarily revealed key hemodynamic and morphological indicators that determine the formation of tandem IAs. The proposed vascular restoration algorithm that provided the pre-aneurysm vasculature might be useful in investigating the flow-driven mechanism of IA growth, thus contributing to the risk evaluation of secondary aneurysm formation.

Clinical Characteristics and Outcome of Patients with Multiple Intracranial Aneurysms from a University Hospital in Nepal

Objective  The risk factors, management strategies, and outcomes of patients with multiple intracranial aneurysms (MIAs) are different compared with that of patients with a single aneurysm. Data are scarce regarding patients with MIAs from developing countries. The objective of this study was to describe the clinical characteristics, management strategies, and outcomes of patients treated microsurgically from Nepal.

Methods  The clinical records of patients confirmed to have MIAs and microsurgically clipped between July 2014 and December 2019 were retrospectively reviewed. Data on demographic and clinical characteristics, computed tomography findings, multiplicity and location of aneurysms, management strategies, and the 1-year outcome were abstracted and analyzed.

Results  Two hundred cerebral aneurysms were microsurgically clipped in 170 consecutive patients during the study period. Twenty-six (13.0%) patients harbored 60 aneurysms. The mean age of the patients was 58.5 (43–73) years. Smoking and hypertension were found in 20 (76.9%) and 16 (61.5%) patients, respectively. The majority of patients [17 (65.4%)] were in good grades at presentation. Twenty-one patients had two aneurysms, four had three aneurysms, and one patient had five aneurysms. The middle cerebral artery was the commonest (20) followed by distal anterior cerebral artery (14) and anterior communicating artery (13) involved in multiplicity. A single-stage surgery was performed on 17 patients. Serial clipping was performed in six patients. In three patients, a single aneurysm on the contralateral side was left untreated for various reasons. The favorable outcome was achieved in 23 (88.5%) patients whereas three (11.5%) patients had an unfavorable outcome. One patient died.

Conclusion  The demographic and clinical characteristics of patients in our series are comparable with those described in the published literature from other countries. With an individualized treatment strategy, an acceptable outcome can be achieved in the majority of the patients.

Why Are Women Predisposed to Intracranial Aneurysm?

Intracranial aneurysm (IA) is a frequent and generally asymptomatic cerebrovascular abnormality characterized as a localized dilation and wall thinning of intracranial arteries that preferentially arises at the arterial bifurcations of the circle of Willis. The devastating complication of IA is its rupture, which results in subarachnoid hemorrhage that can lead to severe disability and death. IA affects about 3% of the general population with an average age for detection of rupture around 50 years. IAs, whether ruptured or unruptured, are more common in women than in men by about 60% overall, and more especially after the menopause where the risk is double-compared to men. Although these data support a protective role of estrogen, differences in the location and number of IAs observed in women and men under the age of 50 suggest that other underlying mechanisms participate to the greater IA prevalence in women. The aim of this review is to provide a comprehensive overview of the current data from both clinical and basic research and a synthesis of the proposed mechanisms that may explain why women are more prone to develop IA.

Neurovascular disease, diagnosis, and therapy: Subarachnoid hemorrhage and cerebral vasospasm

The worldwide incidence of spontaneous subarachnoid hemorrhage is about 6.1 per 100,000 cases per year (Etminan et al., 2019). Eighty-five percent of cases are due to intracranial aneurysms. The mean age of those affected is 55 years, and two-thirds of the patients are female. The prognosis is related mainly to the neurologic condition after the subarachnoid hemorrhage and the age of the patient. Overall, 15% of patients die before reaching the hospital, another 20% die within 30 days, and overall 75% are dead or remain disabled. Case fatality has declined by 17% over the last 3 decades. Despite the improvement in outcome probably due to improved diagnosis, early aneurysm repair, administration of nimodipine, and advanced intensive care support, the outcome is not very good. Even among survivors, 75% have permanent cognitive deficits, mood disorders, fatigue, inability to return to work, and executive dysfunction and are often unable to return to their premorbid level of functioning. The key diagnostic test is computed tomography, and the treatments that are most strongly supported by scientific evidence are to undertake aneurysm repair in a timely fashion by endovascular coiling rather than neurosurgical clipping when feasible and to administer enteral nimodipine. The most common complications are aneurysm rebleeding, hydrocephalus, delayed cerebral ischemia, and medical complications (fever, anemia, and hyperglycemia). Management also probably is optimized by neurologic intensive care units and multidisciplinary teams.

Impact of smoking on course and outcome of aneurysmal subarachnoid hemorrhage

Background

While the smoking-related risk of experiencing an aneurysmal subarachnoid hemorrhage (aSAH) is well established, it remains unclear whether smoking has an unexpected “protective effect” in aSAH, or if smokers are more at risk for complications and poor outcomes.

Methods

Prospective, observational study investigating the course and outcome of aSAH in patients admitted during the years 2011 and 2012. Smoking status at admittance, demographic, medical, and radiological variables were registered along with management, complications, and outcome at 1 year in terms of mortality, modified Rankin score, and Glasgow outcome score extended. We compared current smokers with nonsmokers on group level and by paired analysis matched by aSAH severity, age, and severity of vasospasm.

Results

We included 237 patients, thereof 138 current smokers (58.2%). Seventy-four smoker/nonsmoker pairs were matched. Smokers presented more often in poor clinical grade, had less subarachnoid blood, and were younger than nonsmokers. Ruptured aneurysms were larger, and multiple aneurysms more common in smokers. Severe multi-vessel vasospasm was less frequent in smokers, whereas all other complications occurred at similar rates. Mortality at 30 days was lower in smokers and functional outcome was similar in smokers and nonsmokers. Poor clinical grade, age, cerebral infarction, and vertebrobasilar aneurysms were independent predictors of 1-year mortality and of poor functional outcome. Serious comorbidity was a predictor of 1-year mortality. Smoking did not predict mortality or poor functional outcome.

Conclusions

Notwithstanding clinically more severe aSAH, smokers developed less frequently severe vasospasm and had better outcome than expected. The risk for complications after aSAH is not increased in smokers.

Multiple and mirror intracranial aneurysms: study of prevalence and associated risk factors

OBJECTIVE

Multiple intracranial aneurysms (MIA) account for 30% of all intracranial aneurysms, while mirror aneurysms, a subgroup of MIA, are present in 5% of all patients with cerebral aneurysms. We investigated the risk factors associated with the presence of multiple and mirror intracranial aneurysms.

METHODS

1404 patients, 314 males (22.4%) and 1090 female (77.6%) were enrolled for this study. Diagnosis was performed with a digital subtraction angiography (DSA). Multiplicity was defined as the presence of two or more aneurysms and mirror aneurysms as one pair of aneurysms involving bilateral corresponding arteries. Patients were followed-up from September 2009 till August 2018. Individuals' characteristics such as sex, age, smoking, hypertension and use of contraceptives were evaluated.

RESULTS

Five hundred and twelve patients (36.4%) were diagnosed with MIA, approximately 4%/year. We observed 203 pairs of mirror aneurysms, accounting for 406 aneurysms (13% of the population). There was an increased frequency of females with multiple (p < 0.001, OR = 1.883, 95% CI = 1.386-2.560) and mirror aneurysms (p < 0.001, OR = 2.828, 95% CI = 1.725-4.636). Smoking was associated with multiplicity (p< 0.001, OR = 1.458, 95% CI = 1.160-1.833), as well as advanced age (p < 0.001, OR = 1.938, 95% CI = 1.438-2.611), but there was no significant relation with presence of mirror aneurysms. We observed higher frequency of baby aneurysms (<3mm) in the group of patients with MIA, while giant aneurysms (>25 mm) were most found in patients with only one aneurysm (p < 0.001). No differences between patients who used contraceptives against patients who did not use were found (p = 0.600).

CONCLUSIONS

Gender and smoking, known risk factors to the development of a single intracranial aneurysm, are proportionally increased in patients with MIA. Hypertension and oral contraceptives were not associated with multiplicity.

Risk factors involved in the formation of multiple intracranial aneurysms

BACKGROUND

Although several risk factors of the multiple intracranial aneurysms (MIAs) formation has been reported, the results are controversial. We aimed to find out the risk factors of MIAs formation by analyzing our clinic data combined with a meta-analysis.

MATERIAL AND METHODS

A retrospective review work of medical records for the patients with aneurysms was undertaken. Univariate analysis was used to examine all mentioned variables. Binary logistic regression analysis was used to identify the risk factors of MIAs formation.

RESULTS

In the retrospective review work, a total of 565 patients with aneurysm were included in this study. Of these 565 participants, 449 patients suffered SIAs and 116 patients suffered MIAs. Univariate analysis showed a significant difference in terms of female, cigarette smoking, family history of hypertension, and primary hypertension between the SIAs and MIAs group. The binary logistic regression analysis showed that the female (OR = 1.624), primary hypertension (OR = 1.563), and family history of hypertension (OR = 2.496) were independent risk factors of the formation of MIAs (for each P < 0.05). With regard to the meta-analysis results, it revealed that there was significant difference in the rates of female (P < 0.001), cigarette smoking (P < 0.001), primary hypertension (P = 0.001), and higher age (P = 0.011) among the MIAs patients.

CONCLUSIONS

A higher rate of the formation of MIAs is closely associated with the elder and female. Patients with hypertension history, cigarette smoking, and family primary hypertension history also affected the formation of MIAs, these risk factors should be a guard against.

Epidemiological analysis of 1404 patients with intracranial aneurysm followed in a single Brazilian institution

Background:

We sought to evaluate the epidemiology of intracranial aneurysms in relation to location, gender, age, presence of multiple aneurysms, and comorbidities in the Brazilian population.

Methods:

We performed a prospective analysis of a cohort of 1404 patients diagnosed with intracranial aneurysm admitted to the Hospital das Clinicas of the University of Sao Paulo, a referral hospital for the treatment of cerebrovascular diseases in Brazil. Patients admitted between September 2009 and September 2018 with radiological diagnosis of intracranial aneurysm were included in the study.

Results:

A total of 2251 aneurysms were diagnosed. Females accounted for 1090 aneurysms (77.6%) and the mean age at diagnosis was 54.9 years (ranging 15–88). The most common location was middle cerebral artery (MCA) with 593 aneurysms (26.3%) followed by anterior cerebral artery (ACA) with 417 aneurysms (18.5%) and internal carotid artery in the posterior communicating segment with 405 aneurysms (18.0%). Males had higher rates of ACA aneurysms (29.7%) while females had higher rates of MCA aneurysms (26.1%). Sorting by size, 492 aneurysms were <5 mm (21.8%), 1524 measured 5–10 mm (67.7%), 119 size 11–24 mm (5.3%), and 116 were >24 mm (5.2%). The occurrence of multiple aneurysms was associated with female gender (P < 0.001) and smoking (P < 0.001), but not with hypertension (P = 0.121).

Conclusion:

In this population, the occurrence of intracranial aneurysm is related to several factors, including gender, age, smoking, and hypertension. Our study brought to light important characteristics of a large number of Brazilian patients regarding epidemiology, location, size, and multiplicity of intracranial aneurysms.

Surpass Flow-Diverter in the Treatment of Two Wide-Neck Aneurysms in the Scheme of an Arteriovenous Malformation Patient: A Case Study

BACKGROUND:

The cerebral arterial aneurysm, especially in the circumstances of ateriovenous malformation (AVM), has higher risk of rupture than normal isolated aneursym. Therefore, the treatment strategy needs to be plan very carefully in such case.

CASE PRESENTATION

We report a patient with 2 wide-neck aneurysms located in the feeding artery of the arteriovenous malformation and he, then, was treated by using Surpass stent (flow-diverter) to eliminate the aneurysms.

CONCLUSION:

In our case, multiple wide-neck aneurysms in combination with low risk unruptured AVM, using long Surpass stent-diversion is an effective way to eliminate all the aneurysms in the main feeding artery while still preserving the AVM anatomy.

Multivariate analysis of hemodynamic parameters on intracranial aneurysm initiation of the internal carotid artery

Although fluctuating hemodynamic wall stressors are known to impact intracranial aneurysms (IA) initiation, specificity of those stressors has not been evaluated. In this study, using human IA data, we investigated: (1) specificity of stressors in regions with and without IA eventual IA formation; and (2) how combinations of multiple stressors could improve IA formation prediction. 3D computational vasculatures were constructed based on angiographic images of 18 subjects having multiple closely-spaced IAs in the internal carotid artery. Two models were created: Model A with all IAs computationally removed, Model B which kept keep one IA. Computational fluid dynamics (CFD) simulated flow within models. Based on simulated flow fields, wall shear stress and its gradient (WSS, WSSG), oscillatory shear index (OSI), gradient oscillatory number (GON), aneurysm formation index (AFI), and mean number of swirling flow vortices (MV) were analysed. Multivariate logistic regression determined the accuracy of different combinations of those above-mentioned stressors. Overall, we found that combining hemodynamic stressors improves IA formation prediction over individual indices. Both Model A and Model B's parsimonious model was MV+WSS+GON: AUROC 0.88 and 0.83, respectively. Future studies are planned to understand biological meanings induced by fluctuating stressors.

Association of Bone Mineral Density With the Risk of Intracranial Aneurysm

Importance

Disruption of extracellular matrix integrity is critically involved in both intracranial aneurysm and bone fragility. Furthermore, both intracranial aneurysm and osteoporosis have a female predominance, and sex hormones are considered to affect this discrepancy.

Objective

To evaluate the association between bone mineral density and intracranial aneurysm.

Design, Setting, and Participants

A cross-sectional study conducted with 14 328 patients who underwent brain magnetic resonance angiography and bone mineral densitometry as a part of a health examination at a specialized center for comprehensive health examination in Seoul, the largest metropolitan area in the Republic of Korea, between December 2004 and November 2015. After excluding patients with insufficient clinical information (n = 1102) and with ambiguous intracranial arterial lesion (n = 441), 12 785 were included in the analysis.

Exposures

Bone mineral density was measured at the lumbar vertebrae (L1 to L4), femur neck, and total hip using dual-energy x-ray absorptiometry.

Main Outcomes and Measures

Multiple logistic regression or linear regression was used to examine the association between tertiles of bone mineral density and the presence, size, and multiplicity of intracranial aneurysms. In secondary analyses, we analyzed postmenopausal women and men 50 years and older (n = 8722) because they are particularly at risk of decreased bone mineral density.

Results

Among 12 785 patients in the study (7242 women [56.6%]; mean [SD] age, 54.8 [10.1] years) intracranial aneurysms were found in 472 patients (3.7%). Lower bone mineral density was associated with an increased risk of harboring intracranial aneurysm. In multivariable logistic regression analyses, odds ratios for the highest compared with the lowest bone mineral density tertile were 1.30 (95% CI, 1.03-1.64) in the lumbar spine, 1.30 (95% CI, 1.03-1.64) in the femoral neck, and 1.27 (95% CI, 1.01-1.60) in the total hip after adjusting for age, sex, and vascular risk factors. In a linear regression model adjusted for age, sex, and vascular risk factors, the lowest tertile of bone mineral density in the lumbar spine was associated with an increased log-transformed size of aneurysm (β, 0.196; SE, 0.047). In secondary analyses, these associations were more definite and a low T score (<-1 SD) was additionally associated with multiple aneurysms (OR, 1.84; 95% CI, 1.05-3.30) after adjusting for age, sex, and vascular risk factors.

Conclusions and Relevance

Bone mineral density may be associated with the presence, size, and multiplicity of intracranial aneurysm. The study findings provide evidence for shared pathophysiology between intracranial aneurysm and bone fragility.

Off-Label Application of Pipeline Embolization Device for Intracranial Aneurysms

PURPOSE

The Pipeline embolization device (PED) is approved in the USA for treating giant and large aneurysms arising from the petrous to superior hypophyseal segments of the internal carotid artery in patients older than 21 years of age. This study investigates off-label PED results in a large cohort.

MATERIALS AND METHODS

Retrospective, single-center review of all patients who had off-label PED surgery.

RESULTS

Sixty-two aneurysms (48 patients) underwent off-label PED treatment from 2012- 2017. There were 44 females and four males (age 21 to 75 years; mean/median, 54.3/55.0 years). The most common presenting symptom was headache (47/62, 75.8%). All aneurysms were in the anterior circulation. Aneurysm size ranged from 1.4 to 25.0 mm (mean/median, 7.6/6.9 mm). Fifty-two aneurysms had post-operative imaging with total/near-complete occlusion of 84.6% (44/52). Aneurysm-based operative near-term complication rate was 9.7% while there were no permanent complications. For aneurysms and headache, 86.7% improved/resolved after embo-surgery, and were four times more likely to have a better clinical outcome (resolved or improved symptoms) after surgery (odds ratio [OR], 4.333; P=0.0325). Left-sided aneurysms had a higher occlusion rate (OR, 20; P=0.0073). Hypertension (OR, 4.2; P=0.0332) and smoking (OR, 7; P=0.0155) were more prone towards aneurysm occlusion. Patients without a family history were 14 times more likely to have favorable imaging outcome (P=0.0405). There is no difference of occlusion rates between untreated and previously treated aneurysms (P=0.6894). Overall, occlusion rate decreased by 14% with an increase of aneurysm size by 1 mm (P=0.0283).

CONCLUSION

For anterior circulation aneurysms, the off-label application of PED is as effective and safe as reported for on-label intracranial aneurysms.

Two closely-spaced Aneurysms of the Supraclinoid Internal Carotid Artery: How Does One Influence the Other?

The objective of this study was to use image-based CFD simulation techniques to analyze the impact that multiple closely spaced IAs of the supra-clinioid segment of the ICA have on each other's hemodynamic characteristics. The vascular geometry of fifteen (15) subjects with 2 IAs were gathered using a 3D clinical system. Two groups of computer models were created for each subject's vascular geometry: both IAs present (Model A) and after removal of one IA (Model B). Models were separated into two groups based on IA separation: tandem (one proximal and one distal) and tandem (aneurysms directly opposite on a vessel). Simulations using a pulsatile velocity waveform were solved by a commercial CFD solver. Proximal IAs altered flow into distal IAs (5 of 7), increasing flow energy and spatial-temporally averaged wall shear stress (STA-WSS: 3-50\% comparing Model A to B) while decreasing flow stability within distal IAs. Thus, proximal IAs may ``protect" a distal aneurysm from destructive remodeling due to flow stagnation. Among adjacent IAs, the presence of both IAs decreased each other's flow characteristics, lowering WSS (Model A to B) and increasing flow stability: all changes statistically significant (t-test p < 0.05). A negative relationship exists between the mean percent change in flow stability in relation to adjacent IA volume and ostium area. Closely spaced IAs impact hemodynamic alterations onto each other concerning flow energy, stressors and stability. Understanding these alterations may improve clinical management of closely-spaced IAs.

Concomitant ruptured anterior circulation and unruptured posterior circulation aneurysms: Treatment strategy and review of literature

Basilar artery apex or bifurcation is the most common location for aneurysms arising from posterior cerebral circulation. Reports of unruptured aneurysms of the basilar bifurcation associated with ruptured anterior circulation aneurysms are rare. The presence of multiple intracranial aneurysms poses a significantly high risk to management than a single aneurysm due several factors involved. Surgical management is considered the best treatment modality for most aneurysmal types and location with quite a few limitations when applicable. Authors have conducted a literature review of anterior and posterior circulation concomitant aneurysms and report their own experience with a case of anterior communicating artery blister type aneurysmal rupture presented with the symptoms and signs of subarachnoid hemorrhage concomitant with an unruptured basilar artery bifurcation aneurysm. Moreover, the anomalous origin of thalamoperforators at the basilar apex instead of the posterior cerebral artery makes it reasonably challenging for the microsurgical clipping. Discussed is the clinical presentation, radiological studies obtained, surgical approach utilized with an adequate exposure of the entire circle of Willis as well as the critical decision making when managing these challenging cases.

Characteristics of Intracranial Aneurysms According to Levels of Coronary Artery Calcium

Background and Purpose- Several vascular risk factors are known to be associated with the occurrence of intracranial aneurysms (IAs). Coronary artery calcium (CAC), which reflects the atherosclerotic burden of the coronary arteries, is a known predictor of cardiovascular events and stroke. We investigated the relationship between IA and CAC. Methods- We retrospectively enrolled Korean subjects at a single university hospital who had both brain magnetic resonance angiography and cardiac computed tomography as part of health examinations from January 2010 to July 2017. Subjects were categorized into 4 groups according to CAC score as assessed by cardiac computed tomography: zero (0), low (1-99), intermediate (100-399), or high (≥400). Then, the prevalence of IA in each CAC score group was assessed. We also performed subgroup analysis by age, sex, and location of IA. Results- A total of 4934 subjects (mean age, 54.1±9.8 years; %women, 42.2%) were included for analysis. IAs were detected in 258 subjects (5.23%). The prevalence of IA significantly increased as the CAC score increased (4.8%, 5.4%, 6.4%, and 11.1%, respectively; P for trend, 0.004). In subjects over the age of 50 years, this correlation was more prominent in women than in men (7.1% versus 3.7%, 8.8% versus 4.4%, 8.6% versus 6.3%, and 21.1% versus 10.0%, respectively). Subgroup analysis for the aneurysm location showed that nonbifurcation aneurysm was associated with a high CAC score but bifurcation aneurysm was not. Multivariate logistic regression showed high CAC score was an independent risk factor for the presence of IA compared with zero CAC score (adjusted odds ratio, 2.16; 95% CI, 1.18-3.95). Conclusions- A high CAC score was associated with the presence of IA. This relationship was more prominent in females and nonbifurcation aneurysms.

Dilating Vascular Diseases: Pathophysiology and Clinical Aspects

Atherosclerotic disease of the vessels is a significant problem affecting mortality and morbidity all over the world. However, dilatation of the vessels either in the arterial system or in the venous territory is another vessel disease. Varicocele, pelvic, and peripheral varicose veins and hemorrhoids are aneurysms of the venous vascular regions and have been defined as dilating venous disease, recently. Coronary artery ectasia, intracranial aneurysm, and abdominal aortic aneurysm are examples of arterial dilating vascular diseases. Mostly, they have been defined as variants of atherosclerosis. Although there are some similarities in terms of pathogenesis, they are distinct from atherosclerotic disease of the vessels. In addition, pathophysiological and histological similarities and clinical coexistence of these diseases have been demonstrated both in the arterial and in the venous system. This situation underlies the thought that dilatation of the vessels in any vascular territory should be considered as a systemic vessel wall disease rather than being a local disease of any vessel. These patients should be evaluated for other dilating vascular diseases in a systematic manner.

Intracranial Mirror Aneurysms: Anatomic Characteristics and Treatment Options

Objective

Mirror aneurysms are generally considered as a subset of multiple aneurysms, defined as aneurysms occurring bilaterally and symmetrically on the same-named vessels. Although not infrequent, the characteristics of mirror aneurysms are not well studied. This investigation was conducted to elucidate the anatomic features of such lesions and examine treatment options.

Materials and Methods

A retrospective review was conducted, aimed at 172 patients treated for 344 mirror aneurysms between January 2007 and December 2015. Aneurysms of similar nature but in asymmetric locations on the same-named vessels were excluded. All available records were examined and lesion characteristics, as well as treatment outcomes were assessed.

Results

In study subjects (n = 172), mirror aneurysms most often involved middle cerebral artery bifurcation (n = 83), followed by a paraclinoid internal carotid artery (n = 50) and posterior communicating artery (n = 21). Most of the lesions (95.3%) measured ≤ 10 mm, and in 126 patients (74.6%), the size ratios were > 50%. Of the 344 aneurysms studied, coil embolization was undertaken in 217, surgical clipping in 62, and observation alone (no treatment) in 65. Coil embolization and surgical clipping were done bilaterally in 83 and 12 patients, respectively. In 12 patients, combined coiling and clipping were implemented on each side. Single-stage coil embolization of both the aneurysms was performed in 73 patients, with excellent post-procedural (85.6%) and follow-up (86.8%) occlusive results. There was no procedure-related morbidity or mortality.

Conclusion

By adopting different treatment strategies to different configurations and vascular sources, mirror aneurysms can be safely and effectively treated. If feasible, single-stage coil embolization should be considered as a reasonable treatment option for mirror aneurysms.

Morphological Parameters Related to Aneurysm Wall Enhancement in Patients with Multiple Intracranial Aneurysms

BACKGROUND

Vessel wall magnetic resonance imaging (MRI) has been suggested as a potential in vivo method to detect inflammation of aneurysm wall and identify unruptured intracranial aneurysm (UIA) at high risk for rupture. This study aims to investigate the correlation between aneurysm wall enhancement (AWE) on vessel wall MRI and rupture-related morphological parameters in patients with multiple UIAs.

METHODS

Clinical data and vessel wall MRI images were reviewed in 14 patients with 30 multiple UIAs. The AWE was defined as enhancement of the aneurysm wall in postcontrast vessel wall MRI using the precontrast MRI as a reference. Morphological parameters, including aneurysm size, aspect ratio, size ratio, bottleneck factor, height-to-width ratio, nonsphericity index (NSI), and inflow angle, were measured using 3-dimensional rotation angiography. Univariate and multivariate analyses were performed to evaluate the correlations between morphological parameters and the presence of AWE.

RESULTS

Sixteen of the 30 multiple UIAs presented with AWE on vessel wall MRI. On univariate analyses, UIAs with AWE were significantly larger (P = 0.001) and had significantly higher aspect ratio (P = 0.047), size ratio (P = 0.003), bottleneck factor (P = 0.007), and NSI (P = 0.007) values. Further multivariate logistic regression showed that aneurysm size (odds ratio, 3.54; 95% confidence interval, 1.10-11.35; P = 0.033) and NSI (odds ratio, 3.53; 95% confidence interval, 1.06-11.80; P = 0.040) were independently associated with the presence of AWE in multiple UIAs.

CONCLUSIONS

The presence of AWE on vessel wall MRI was significantly correlated with conventional morphological rupture risk factors in patients with multiple UIAs, which might indicate AWE as a potential radiologic predictor for UIAs with high rupture risk.

Subarachnoid Aneurysmal Hemorrhage Associated with Coarctation of the Aorta: Case Report and Review of the Literature

Intracranial aneurysms (IAs) that undergo rupture causing subarachnoid hemorrhage (SAH), are common in young patients with coarctation of the aorta (CoA), but rarer in middle-aged and elderly patients. The pathogenesis of IAs associated with CoA remains unclear. We report the case of a 50-year-old woman who presented with SAH. On evaluation, six IAs were distributed among the anterior communicating artery (ACoA) (ruptured), distal segments of both anterior cerebral arteries (ACA), the left internal carotid artery (ICA), the bifurcation of the left middle cerebral artery (MCA)/MCA early branch, and the inferior trunk of the left MCA. CoA was also diagnosed. The ruptured ACoA IA, and two other unruptured IAs, were successfully clipped during emergency surgery. Postoperative intensive care was instituted to avoid cerebral vasospasm and renal or spinal cord ischemia. During the same hospitalization, the remaining three IAs were clipped at a second surgery. She was discharged with slight cognitive impairment eighty days after admission. Subsequently, she underwent elective treatment for the CoA. According to the literature, IAs associated with CoA have a higher tendency to involve the ACoA than IAs without CoA. Moreover, adult CoA patients tend to have multiple IAs, considered to be due to hypertension associated with CoA, as well as genetic predisposition. In CoA patients, ruptured IAs should be treated as early as possible before correction of the CoA. Close postoperative observation with management of cerebral vasospasm, renal or spinal cord ischemia, and respiratory compromise in the perioperative period is vital.

Aneurysmal subarachnoid haemorrhage (aSAH): Five consecutive years' experience of Fars province, Iran

OBJECTIVE

Subarachnoid haemorrhage (SAH), caused by the rupture of intracranial aneurysms, is a devastating event with high rates of morbidity and mortality. Aneurysmal subarachnoid haemorrhage (aSAH) plays a critical role in the potential loss of life as its sufferers are usually of a young age. We aimed to investigate the incidence of aSAH along with the patients' characteristics over five consecutive years in Fars, a large province located in Southern Iran.

METHODS

In this prospective study, anonymous data of all patients diagnosed with aSAH in Fars province were collected after patient admission and surgery. Data from the last national census in 2011 were used to calculate the incidence. The data were analysed using SPSS software version 18 using independent sample t test, chi square test and ANOVA. The significance level was set at 0.05.

RESULTS

The number of aSAH cases identified in Fars, Iran, each year varied between 78 (2011) and 98 (2015) for a total of 421 aSAH cases within the 5-year study period. The annual aSAH incidence estimates showed no differences and were 1.65 [95% confidence interval (CI): 1.58-1.72], 1.70 (95%CI: 1.68-1.72), 1.71 (95%CI: 1.63-1.78), 1.82 (95%CI: 1.74-1.9), and 2.05 (95%CI: 1.97-2.13) per 100,000 persons, respectively, for the five consecutive years from 21 March 2011 to 20 March 2016. Hypertension was the most common risk factor, and was found in 198 (48%) aSAH patients. Ninety-four (22.5%) patients had moderate hydrocephalus on admission. Middle cerebral artery and anterior communicating artery were the most common sites of aneurysms. On admission, 351 (83%) patients had a Glasgow Coma Scale score >7, 197 (47%) presented with Hunt and Hess score of 1, and 365 (87%) had a Fisher score of ≤3. Multiple aneurysms were found in 59 (14%) of the 421 cases and the most common risk factors in multiple aneurysms were hypertension in 30 (51%) and smoking in 26 (44%) cases. Survival data were available only on patients diagnosed in year 2015, and the six-month survival rate was 89.8%.

CONCLUSIONS

This study revealed that although the incidence of aSAH remained stable, the survival of aSAH patients who reached the hospital alive and were operated on, improved in Shiraz (the six-month survival rate was 89.8% in year 2015). The incidence and survival study on aSAH in other geographic areas of Iran as a multi-centre study is recommended. There is a need to inform primary healthcare workers regarding the possibility of aSAH in a patient with signs of the sentinel headache.

Multiple intracranial aneurysms: a direct hemodynamic comparison between ruptured and unruptured vessel malformations

PURPOSE

Despite numerous studies addressing the rupture risk of intracranial aneurysms that have been published, the assessment thereof still remains challenging. Image-based simulations enable a precise prediction of patient-specific blood flow information. However, those approaches normally consider only small segments of the complete cerebral vasculature.

METHODS

To test the validity of the consideration of single aneurysms in one computational setup, domains of the complete anterior and posterior circulations with multiple intracranial aneurysms (MIA) were simulated. Six patients with MIA were investigated, while 3D surfaces of eleven unruptured and six ruptured aneurysms were segmented. The segmentations were used for the determination of morphological parameters and also for image-based blood flow simulations used to characterize the hemodynamic properties of each aneurysm.

RESULTS

In the geometric comparison, neck aspect ratios of unruptured and ruptured aneurysms did not differ significantly. In contrast, size ratios, aspect ratios, surface areas, volumes, and non-sphericity indices were significantly higher in the ruptured cases. The analysis of hemodynamic parameters demonstrated that in each patient, the ruptured aneurysm exhibited the lowest averaged wall shear stresses and highest oscillatory shears. Unstable flow was also detected in ruptured aneurysms based on increased oscillatory velocity.

CONCLUSION

In this small study involving patients with MIA, different morphologies and flow patterns were observed between ruptured and unruptured aneurysms. The analysis of the hemodynamics in such patients revealed a good agreement with studies that only considered single malformations. Additionally, complex flow patterns are detected in ruptured cases, which require deeper investigation.

The cerebral basal arterial network: morphometry of inflow and outflow components

The aim of this project was to study how the morphology of the incoming and outgoing arterial components of the cerebral basal arterial network influence the blood flow to the brain. The cerebral basal arterial network consists of the circulus arteriosus cerebri anteriorly and the basilar artery posteriorly. Diameters of inflow vessels (bilateral vertebral and internal carotid arteries), connecting vessels (anterior communicating, basilar and bilateral posterior communicating arteries) and outflow vessels (anterior, middle and posterior cerebral arteries) were measured and cross-sectional areas calculated in 51 cadaveric brain specimens. The individual and the average cross-sectional areas of inflow arteries (51.43 mm² ) were significantly bigger than the major outflow arteries (37.76 mm² ) but smaller than the combined cross-sectional areas of outflow (37.76 mm² ) and connecting (25.33 mm² ) arteries. The difference in the size of arterial cross-sectional area and the presence of the connecting arteries in the cerebral basal arterial network provides a mechanism for lowering peaks in pressure, and demonstrates a function of the cerebral basal arterial network.

A Patient with Eight Intracranial Aneurysms: Endovascular Treatment in Two Sessions

The frequency of multiple intracranial aneurysms seen in patients with or without subarachnoid hemorrhage is high. The advancement of the endovascular technique and devices has ensured that endovascular treatment of intracranial aneurysms is the first choice in most cases, especially in unruptured ones. Different combinations of treatment modalities and techniques can be used in the management of multiple aneurysms. But in selected patients without subarachnoid hemorrhage, treatment of all aneurysms in one or more sessions with endovascular techniques is less traumatic than that with surgery. In the literature, the maximum number of aneurysms in one patient treated endovascularly and/or surgically is seven. In this case report, we present, with a review of the literature, a patient with eight intracranial aneurysms, all of which were treated in two sessions with various endovascular techniques. A 40-year-old female patient was admitted due to headache. Angiography showed eight aneurysms in the posterior circulation and, bilaterally, in the anterior circulation. All aneurysms were treated endovascularly in two sessions. In the treatment of the aneurysms, different endovascular techniques were used including flow diverters stents, stent-assisted coiling, Y-stent-assisted coiling, and coiling alone.

A 54-year-old man with 12 intracranial aneurysms and familial subarachnoid hemorrhage: case report

Unruptured intracranial aneurysms occur in 1-3 % of the general population, and the risk of rupture is generally considered to be low. However, patients with multiple aneurysms and familial predisposition carry a particular risk of subarachnoid hemorrhage (SAH). A 54-year-old hypertensive man underwent screening with a head CT angiography (CTA) because of his comorbidities. CTA revealed multiple bilateral aneurysms around the circle of Willis. At first surgery, seven aneurysms were clipped (BA, ACOM, ICA ×2, and MCA ×3), two of which were detected intraoperatively only. During the second surgery, another three aneurysms were surgically clipped (PCOM and MCA ×2), one of which was detected intraoperatively. Follow-up angiography revealed another two aneurysms. A PCOM aneurysm was treated by coil embolization and a VA aneurysm clipped surgically during a third admission. The patient made an uneventful recovery. However, 4 months after his second surgery, his daughter underwent surgical clipping of a right-sided ICA aneurysm. This case report highlights both the importance of screening of high risk patients with family history of SAH, as well as its limitations, as our patient developed two de novo aneurysms during 6-month follow-up and CTA preoperatively missed three small aneurysms.

Correlation Between Aneurysm Size and Hemodynamics in One Individual with Multiple Small Intracranial Aneurysms

Objective

A large number of cases are needed in the patient-specific modeling of intracranial aneurysms to establish the statistical significance due to individual variation of risk factors that are difficult to account for. However, these risk factors are critical in hemorrhage risk as demonstrated in large clinical studies. Rupture risks for aneurysms in an individual are easier to compare because these aneurysms are under the same physiological environment, and their only differences are the local hemodynamic factors associated with their anatomic locations.

Methods

Eight small aneurysms (< 7 mm) from one individual were analyzed using patient-specific hemodynamic modeling. Four scenarios with different perfusion assumptions were performed to account for the flow rate at two smaller communicating arteries. Wall shear stresses (WSS) at these aneurysms were compared to determine their relationship with the aneurysm size.

Results

Each of the three largest aneurysms is either the most proximal or distal aneurysm in a given artery so that blood pressure does not have a direct influence on aneurysm size. No wall shear stress-derived hemodynamic variables are found to be related to aneurysm size.

Discussion

A study of multiple aneurysms from one individual offers a unique opportunity to examine various hemodynamic factors without selection biases. Aneurysms greater than 4 mm (Group 1) have a higher product of maximum WSS and area of low WSS; aneurysms smaller than 4 mm (Group 2) have a lower product of maximum WSS and area of low WSS. In addition, aneurysm size is linearly correlated with the flow rate at the parent artery in each group.

Factors Predicting Poor Outcome in a Surgically Managed Series of Multiple Intracranial Aneurysms

OBJECTIVE

Multiple factors are known to influence outcomes in single-aneurysm subarachnoid hemorrhage, such as Hunt and Hess (H&H) grade, hypertension, etc. We sought to assess the influence of individual risk factors on outcome in surgically managed patients with multiple intracranial aneurysm.

METHODS

A retrospective review of consecutive 780 patients of subarachnoid hemorrhage revealed multiple intracranial aneurysm in 63 patients with 146 aneurysms. Clinicoradiologic features, hospital course, and outcome obtained via use of the Glasgow Outcome Score were noted from hospital records. H&H grade was divided into 2 groups as good and poor whereas Glasgow Outcome Score at 1 month was divided into 2 groups as favorable and unfavorable for analysis. To test association among variables, a χ(2) test/Fisher exact test was used. Risk was calculated in exposure group by the use of univariate logistic regression and multivariate analysis (binary logistic regression model).

RESULTS

A definite female preponderance was observed (male/female ratio: 1:2.71). The most common site was middle cerebral artery bifurcation (overall and male patients, n = 43); in women, it was internal carotid artery bifurcation. Anterior communicating artery aneurysm was the most common to bleed (n = 22). Early presentation resulted in worse outcomes (<4: 4-21: >21days = 44:37:33, P = .844). Vasospasm and infarct incidence was greatest in the group 4-14 days (n = 37). Infarct evolved in 15 patients (8 in territory of aneurysmal dissection/distribution). Factors influencing patient outcomes were age ≥65 years (P = 0.037), H&H grade (P = 0.04), posterior communicating artery distribution of aneurysm (P = 0.03), hypertension (P = 0.03), infarct (P = 0.001), and hydrocephalus (P = 0.01) CONCLUSIONS: Poor H&H grade, hypertension, posterior communicating artery distribution, elderly age, infarct, and hydrocephalus each influenced poor outcomes at 1 month. Hydrocephalus is predictive of poor outcome.

Sex Differences in the Formation of Intracranial Aneurysms and Incidence and Outcome of Subarachnoid Hemorrhage: Review of Experimental and Human Studies

Intracranial aneurysms are defined as pathological dilatations of cerebral arteries and rupture of intracranial aneurysms leads to subarachnoid hemorrhage (SAH). The goal of this review was to outline the sex differences in the formation and progression of intracranial aneurysms as well as sex-related differences in incidence and outcome of SAH. The literature review was performed using PubMed with a combination of these search terms: "subarachnoid hemorrhage," "incidence," "outcome," "sex," "gender," "male," "female," "experimental," "mice," and "rats." Studies written in English were used. Female sex is thought to be a risk factor for aneurysm formation, especially in postmenopausal age populations, suggesting the potential protective involvement of sex steroids. Female sex is also considered a risk factor for SAH occurrence. Although incidence and mortality are confirmed to be higher in females in most studies, they elucidated no clear differences in the functional outcome among SAH survivors. The effect of gender on the pathophysiology of SAH is not very well understood; nevertheless, the majority of pre-clinical studies suggest a beneficial effect of sex steroids in experimental SAH. Moreover, conflicting results exist on the role and effect of hormone replacement therapies and oral contraceptive pills on the incidence and outcome of human SAH. Sex differences exist in the formation of aneurysms as well as the incidence and mortality of SAH. Potential therapeutic effects of sex steroids have been replicated in many animal studies, but their potential use in the treatment of acute SAH in human populations needs more future study.

The safety of vasopressor-induced hypertension in subarachnoid hemorrhage patients with coexisting unruptured, unprotected intracranial aneurysms

OBJECT

Vasopressor-induced hypertension (VIH) is an established treatment for patients with aneurysmal subarachnoid hemorrhage (SAH) who develop vasospasm and delayed cerebral ischemia (DCI). However, the safety of VIH in patients with coincident, unruptured, unprotected intracranial aneurysms is uncertain.

METHODS

This retrospective multiinstitutional study identified 1) patients with aneurysmal SAH and 1 or more unruptured, unprotected aneurysms who required VIH therapy (VIH group), and 2) patients with aneurysmal SAH and 1 or more unruptured, unprotected aneurysms who did not require VIH therapy (non-VIH group). All patients had previously undergone surgical or endovascular treatment for the presumed ruptured aneurysm. Comparisons between the VIH and non-VIH patients were made in terms of the patient characteristics, clinical and radiographic severity of SAH, total number of aneurysms, number of ruptured/unruptured aneurysms, aneurysm location/size, number of unruptured and unprotected aneurysms during VIH, severity of vasospasm, degree of hypervolemia, and degree and duration of VIH therapy.

RESULTS

For the VIH group (n = 176), 484 aneurysms were diagnosed, 231 aneurysms were treated, and 253 unruptured aneurysms were left unprotected during 1293 total days of VIH therapy (5.12 total years of VIH therapy for unruptured, unprotected aneurysms). For the non-VIH group (n = 73), 207 aneurysms were diagnosed, 93 aneurysms were treated, and 114 unruptured aneurysms were left unprotected. For the VIH and non-VIH groups, the mean sizes of the ruptured (7.2 ± 0.3 vs 7.8 ± 0.6 mm, respectively; p = 0.27) and unruptured (3.4 ± 0.2 vs 3.2 ± 0.2 mm, respectively; p = 0.40) aneurysms did not differ. The authors observed 1 new SAH from a previously unruptured, unprotected aneurysm in each group (1 of 176 vs 1 of 73 patients; p = 0.50). Baseline patient characteristics and comorbidities were similar between groups. While the degree of hypervolemia was similar between the VIH and non-VIH patients (fluid balance over the first 10 days of therapy: 3146.2 ± 296.4 vs 2910.5 ± 450.7 ml, respectively; p = 0.67), VIH resulted in a significant increase in mean arterial pressure (mean increase over the first 10 days of therapy relative to baseline: 125.1% ± 1.0% vs 98.2% ± 1.2%, respectively; p < 0.01) and systolic blood pressure (125.6% ± 1.1% vs. 104.1% ± 5.2%, respectively; p < 0.01).

CONCLUSIONS

For small, unruptured, unprotected intracranial aneurysms in SAH patients, the frequency of aneurysm rupture during VIH therapy is rare. The authors do not recommend withholding VIH therapy from these patients.

Seven Intracranial Aneurysms in One Patient: Treatment and Review of Literature

Before the advent of endovascular coiling, patients with multiple intracranial aneurysms were treated with surgical clipping; however, with the advancements in endovascular technology, intracranial aneurysms can be treated with surgical clipping and/or endovascular coiling. We describe a case of subarachnoid hemorrhage in a patient with 7 intracranial aneurysms. A 45-year-old female developed a sudden headache and left sided hemiparesis. Initial workup showed a subarachnoid hemorrhage in the right Sylvian fissure. Further angiographic workup showed 7 intracranial aneurysms (left and right middle cerebral artery bifurcation, right middle cerebral artery, anterior communicating artery, left posterior communicating artery, right posterior inferior cerebellar artery, and left superior cerebellar artery). The patient underwent two craniotomies for surgical clipping of the anterior circulation aneurysms and endovascular stent-assisted coils for the posterior circulation aneurysms. The need for anti-platelet agents for endovascular treatment of the posterior circulation aneurysms and clinical presentation warranted surgical clipping of the anterior circulation aneurysms prior to endovascular therapy. We describe a case report and decision making for a patient with multiple intracranial aneurysms treated with surgical clipping and endovascular coiling.

Morphologic and Hemodynamic Analysis in the Patients with Multiple Intracranial Aneurysms: Ruptured versus Unruptured

Background and Purpose

The authors evaluated the impact of morphologic and hemodynamic factors on multiple intracranial aneurysms and aimed to identify which parameters can be reliable indexes as one aneurysm ruptured, and the others did not.

Methods

Between June 2011 and May 2014, 69 patients harboring multiple intracranial aneurysms (69 ruptured and 86 unruptured) were analyzed from 3D-digital subtraction angiography (DSA) images and computational fluid dynamics (CFD). Morphologic and hemodynamic parameters were evaluated for significance with respect to rupture. Receiver operating characteristic (ROC) analysis identified area under the curve (AUC) and optimal thresholds separating ruptured from unruptured intracranial aneurysms for each parameter. Significant parameters were examined by binary logistic regression analysis to identify independent discriminators.

Results

Nine morphologic (size, neck width, surface area, volume, diameter of parent arteries, aspect ratio, size ratio, lateral/bifurcation type and regular/irregular type) and 6 hemodynamic (WSSmean, WSSmin, OSI, LSA, flow stability and flow complexity) parameters achieved statistical significance (p<0.05). Six morphologic (size, surface area, volume, aspect ratio, size ratio and regular/irregular type) and five hemodynamic (WSSmean, WSSmin, LSA, flow stability and flow complexity) parameters had high AUC values (AUC>0.7). By binary logistic regression analysis, large aspect ratio and low WSSmean were the independently significant rupture factors (AUC, 0.924; 95% CI, 0.883–0.965).

Conclusions

Large aspect ratio and low WSSmean were independently associated with the rupture status of multiple intracranial aneurysms.

Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a worldwide health burden with high fatality and permanent disability rates. The overall prognosis depends on the volume of the initial bleed, rebleeding, and degree of delayed cerebral ischemia (DCI). Cardiac manifestations and neurogenic pulmonary edema indicate the severity of SAH. The International Subarachnoid Aneurysm Trial (ISAT) reported a favorable neurological outcome with the endovascular coiling procedure compared with surgical clipping at the end of 1 year. The ISAT trial recruits were primarily neurologically good grade patients with smaller anterior circulation aneurysms, and therefore the results cannot be reliably extrapolated to larger aneurysms, posterior circulation aneurysms, patients presenting with complex aneurysm morphology, and poor neurological grades. The role of hypothermia is not proven to be neuroprotective according to a large randomized controlled trial, Intraoperative Hypothermia for Aneurysms Surgery Trial (IHAST II), which recruited patients with good neurological grades. Patients in this trial were subjected to slow cooling and inadequate cooling time and were rewarmed rapidly. This methodology would have reduced the beneficial effects of hypothermia. Adenosine is found to be beneficial for transient induced hypotension in 2 retrospective analyses, without increasing the risk for cardiac and neurological morbidity. The neurological benefit of pharmacological neuroprotection and neuromonitoring is not proven in patients undergoing clipping of aneurysms. DCI is an important cause of morbidity and mortality following SAH, and the pathophysiology is likely multifactorial and not yet understood. At present, oral nimodipine has an established role in the management of DCI, along with maintenance of euvolemia and induced hypertension. Following SAH, hypernatremia, although less common than hyponatremia, is a predictor of poor neurological outcome.