Background: A relationship between the geometry and symmetry of Willis\' circle and intracranial aneurysms was reported for anterior communicating and posterior communicating (PCom) aneurysms. A similar association with the middle cerebral artery (MCA) aneurysms instead appeared weaker. Methods: We reviewed 432 patients from six Italian centers with unilateral MCA aneurysms, analyzing the relationship between the caliber and symmetry of Willis\' circle and the presence of ruptured and unruptured presentation. CT-angiograms were evaluated to assess Willis\' circle geometrical characteristics and the MCA aneurysm side, dimension and rupture status. Results: The hypoplasia of the first segment of the anterior cerebral artery (A1) was in approximately one-quarter of patients and PCom hypoplasia was in almost 40%. About 9% had a fetal PCom ipsilaterally to the aneurysm. By comparing the aneurysmal and healthy sides, only the PCom hypoplasia appeared significantly higher in the affected side. Finally, the caliber of the internal carotid artery (ICA) and the first segment of MCA (M1) caliber were significantly greater in patients with unruptured aneurysms, and PCom hypoplasia appeared related to the incidence of an ipsilateral MCA aneurysm and its risk of rupture. Conclusions: Although according to these findings asymmetries of Willis\' circle are shown to be a risk factor for MCA aneurysm formation and rupture, the indifferent association with ipsilateral or contralateral hypoplasia remains a datum of difficult hemodynamic interpretation, thereby raising the concern that this association may be more casual than causal.

OBJECTIVE: The objective of this research was to explore the difference and correlation of the morphological and hemodynamic features between sidewall and bifurcation aneurysms in anterior circulation arteries, utilizing computational fluid dynamics as a tool for analysis.
METHODS: In line with the designated inclusion criteria, this study covered 160 aneurysms identified in 131 patients who received treatment at Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, China, from January 2021 to September 2022. Utilizing follow-up digital subtraction angiography (DSA) data, these cases were classified into two distinct groups: the sidewall aneurysm group and the bifurcation aneurysm group. Morphological and hemodynamic parameters in the immediate preoperative period were meticulously calculated and examined in both groups using a three-dimensional DSA reconstruction model.
RESULTS: No significant differences were found in the morphological or hemodynamic parameters of bifurcation aneurysms at varied locations within the anterior circulation. However, pronounced differences were identified between sidewall and bifurcation aneurysms in terms of morphological parameters such as the diameter of the parent vessel (Dvessel), inflow angle (θF), and size ratio (SR), as well as the hemodynamic parameter of inflow concentration index (ICI) (P<0.001). Notably, only the SR exhibited a significant correlation with multiple hemodynamic parameters (P<0.001), while the ICI was closely related to several morphological parameters (R>0.5, P<0.001).
CONCLUSIONS: The significant differences in certain morphological and hemodynamic parameters between sidewall and bifurcation aneurysms emphasize the importance to contemplate variances in threshold values for these parameters when evaluating the risk of rupture in anterior circulation aneurysms. Whether it is a bifurcation or sidewall aneurysm, these disparities should be considered. The morphological parameter SR has the potential to be a valuable clinical tool for promptly distinguishing the distinct rupture risks associated with sidewall and bifurcation aneurysms.

UNASSIGNED: Ischemic complications develop after elective coil embolization procedures at a certain rate. The prevention of these events has been a longstanding issue for many interventional neuroradiologists. This study aimed to clarify whether procedural ischemic events after unruptured aneurysm embolization decrease over time with perioperative anti-thromboembolic treatment or surgical experience.
UNASSIGNED: This study included patients with cerebral aneurysms in our institution between July 2012 and June 2020. Dual-antiplatelet therapy (DAPT) was performed (Phase 1). Thromboembolic events developed at a certain rate; thus, rivaroxaban was administered with single-antiplatelet therapy (SAPT) to improve thromboembolic results (Phase 2), showing better outcomes than in Phase 1. Subsequently, DAPT was administered again (Phase 3). Ischemic complications were evaluated in each phase or compared between the DAPT group and the direct oral anticoagulant (DOAC) with the clopidogrel (DOAC+SAPT) group.
UNASSIGNED: Relatively, fewer symptomatic ischemic events were noted in Phase 2 or the DOAC+SAPT group, but the outcome was not better in Phase 3 than in Phase 2. Symptomatic complications were more common in Phase 3 than in Phases 1 and 2.
UNASSIGNED: Ischemic complications occurred at a certain rate after endovascular procedures for unruptured aneurysms. The incidence did not decrease over time; particularly, standard DAPT plus postoperative anti-thromboembolic medication did not adequately decrease complications in Phase 3 compared to Phases 1 and 2. Therefore, accumulated experience or a learning curve could not explain the results. DOAC administration might decrease the risk of these events, but further accumulation of evidence or prospective investigation is warranted.

The decision for treatment for unruptured intracranial aneurysms (UIAs) is often difficult. Innovation in endovascular devices have improved the benefit-to-risk profile especially for elderly patients; however, the treatment guidelines from the past decade often recommend conservative management. It is unknown how these changes have affected the overall age of the patients selected for treatment. Herein, we aimed to study potential changes in the average age of the patients that are being treated over time.
A systematic search of the literature was performed to identify all studies describing the age of the UIAs that were treated by any modality. Scatter diagrams with trend lines were used to plot the age of the patients treated over time and assess the presence of a potential significant trend via statistical correlation tests.
A total of 280 studies including 83,437 UIAs treated between 1987 and 2021 met all eligibility criteria and were entered in the analysis. Mean age of the patients was 55.5 years, and 70.7% were female. There was a significant increasing trend in the age of the treated patients over time (Spearman r: 0.250; P < 0.001), with a 1-year increase in the average age of the treated patients every 5 years since 1987.
The present study indicates that based on the treated UIA patient data published in the literature, older UIAs are being treated over time. This trend is likely driven by safer treatments while suggesting that re-evaluation of certain UIA treatment decision scores may be of great interest.

In the absence of clear guidelines and consistent natural history data, the decision to treat unruptured intracranial aneurysms (UIAs) is a matter of some controversy. Currently, decisions are often guided by a consensus of cerebrovascular specialist teams and patient preferences. It is unclear how paradigm-shifting developments in the detection and treatment of UIAs have affected the size of the UIAs that are selected for treatment. Herein, the authors aimed to study potential changes in the average size of the UIAs that were treated over time. They hypothesized that the average size of UIAs that are treated is decreasing over time.
A systematic search of the literature was performed to identify all studies describing the size of UIAs that were treated using any modality. Scatter diagrams with trend lines were used to plot the size of the aneurysms treated over time and assess for the presence of a potentially significant trend via statistical correlation tests. Subgroup analyses based on type of treatment, country of study, and specialty of the authors were performed.
A total of 240 studies including 35,150 UIAs treated between 1987 and 2021 met all eligibility criteria and were entered in the analysis. The mean age of patients was 55.5 years, and 70.7% of the patients were females. There was a significant decrease in the size of treated UIAs over time (Spearman\'s r = -0.186, p < 0.001), with a 0.71-mm decrease in the average size of treated UIAs every 5 years since 1987 and an annual mean dropping below 7 mm in 2012. This decreasing trend was present in surgically and endovascularly treated UIAs (p < 0.001 for both), in more developed and developing countries (p < 0.001 for both), within neurosurgical and non-neurosurgical specialties (p < 0.001 for both), most prominently in the US (Spearman\'s r = -0.482, p < 0.001), and less prominently in Europe (Spearman\'s r = -0.221, p < 0.001) and was not detected in East Asia.
The present study indicates that based on the treated UIA size data published in the literature over the past 35 years, smaller UIAs are being treated over time. This trend is likely driven by safer treatments. However, future studies should elucidate the cost-effectiveness of treating smaller UIAs as well as the possible real-world contribution of this trend in preventing aneurysmal subarachnoid hemorrhage.

BACKGROUND: Strong evidence demonstrates that race is associated with health outcomes. Previous neurosurgical research has focused predominantly on subjective data, such as patient satisfaction. Our objective was to assess whether racial disparities are present in primary objective outcomes for treatment of intracranial, unruptured aneurysms in the United States.
METHODS: Data from the 2012-2015 National Inpatient Sample (NIS) database was analyzed. Patients who underwent either open or endovascular treatment of unruptured intracranial aneurysms were included (n = 11663). Patients were stratified by race, and those of unknown race or whose race sample size was too underpowered for analysis were excluded (n = 1202), along with those who experienced head trauma (n = 110) or concurrent AVM (n = 71). Poor outcome was defined as in-hospital mortality, discharge to a nursing facility or hospice, placement of a tracheostomy tube, or placement of a gastrostomy tube. The associations between race and adverse outcomes were determined through multivariate logistic regression, corrected for potentially confounding variables such as age, sex, procedural type, elective procedure, obesity, diabetes, tobacco, severity of illness, and hospital type.
RESULTS: 7478 White, 1460 Black, 1086 Hispanic, and 279 Asian patients were included in the final analysis. Complication rates were not significantly different between races, however Black patients experienced the highest proportion of complications (24 %). After adjusting for confounders, the odds of poor outcomes were significantly higher for Black patients (OR = 1.32 95 % CI: 1.07-1.62; p = 0.008) when compared to White patients. Black and Hispanic patients demonstrated a longer length of stay (Black, B: 0.04; 95 % CI: 0.03, 0.06; p < 0.001; Hispanic, B: 0.04; 95 % CI: 0.02, 0.05; p < 0.001) when compared to White patients.
CONCLUSIONS: Our nationwide analysis using the NIS suggests that Black patients treated for unruptured intracranial aneurysms experience worse outcomes and longer lengths of stay when compared to White patients. Recognizing the differences in objective outcomes and the presence of neurosurgical healthcare disparities is an important first step in providing equitable care to all patients. Future studies that carefully follow the social determinants of health and consider more confounding factors in the association between outcomes and determinants are needed.

Objective: The coiling and clipping of unruptured cerebral aneurysms (UCAs) in older patients has increased rapidly, and aneurysm size was a significant factor for decision-making in the treatment of UCAs. The purpose of the study was to investigate the impact of age on the functional outcomes of patients between the small versus large UCAs. Methods: We conducted a retrospective study for consecutive cases of UCAs admitted from May 2011 to December 2020. According to the maximum diameter of UCA, patients were divided into small UCAs (≤ 5 mm) group and large UCAs (>5 mm) group. Baseline characteristics, clinical complications, and outcomes of patients between the two groups were analyzed. Results: A total of 564 UCA patients received preventive treatment, including 165 small UCAs and 399 large UCAs. Compared with the small UCA group, the incidence of ischemia event in the large UCA group was significantly higher (7.3 vs. 2.4%; p = 0.029). Multivariable analysis demonstrating age (p = 0.006) and treatment modality (p < 0.001) were independent risk factors associated with poor outcome for patients with large UCAs. Conclusions: Preventive treatment of small UCAs is safe and effective, but older patients with large UCAs are at high risk of poor outcome, and the operations should be more cautious.

Interhospital competition has been shown to affect surgical outcomes and expenditures. However, interhospital competition\'s impact on neurosurgery is poorly characterized.
To assess how interhospital competition is associated with treatment strategy and outcomes for unruptured intracranial aneurysms (UIAs).
We identified all elective UIA admissions in the National Inpatient Sample from 2002 to 2011. Competitive intensity of each hospital market was quantified using the validated Herfindahl-Hirschman Index (HHI), with lower values denoting higher competition. We then obtained nationwide HHI values for 2012 to 2016 from the Health Care Cost Project. Outcomes included treatment modality (clipping, coiling, or nonoperative management), inpatient mortality, disposition, complications, length of stay (LOS), and costs. Multivariate regression assessed the association between HHI and outcomes, controlling for patient demographics, severity metrics, hospital characteristics, and treatment.
We studied 157 979 elective UIA admissions at 1435 hospitals from 2002 to 2011, with an increase in coiling admissions (13.4% to 33.7%) and decrease in clipping admissions (30.9% to 17.6%). Mean hospital HHI was 0.11 (range = 0.001-0.97). Competition decreased for 61.8% of hospitals from 2002 to 2011 and 68.1% of metropolitan localities from 2012 to 2016. Admissions in more competitive hospital markets exhibited increased odds of undergoing surgery (odds ratio [OR] = 1.37, P < .001), with preference toward coiling over clipping (OR = 1.27, P < .001). HHI was not associated with mortality, disposition, or LOS. However, increased interhospital competition was associated with more complications (OR = 1.09, P = .001) and greater hospital costs (β-coefficient = 1.06, P < .001).
For UIA patients, admission to hospitals in more competitive geographies was associated with increased rates of surgical intervention, coiling utilization, complications, and hospitalization costs.

Unruptured intracranial aneurysms (UIAs) are common and are being detected with increasing frequency given the improved quality and higher frequency of cross-sectional imaging. The long-term natural history of UIAs remains poorly understood. To date, there is relative lack of clear guidelines for selection of patients with UIAs for treatment. Surveillance imaging for untreated UIAs is frequently performed, but frequency, duration, and modality of surveillance imaging need clearer guidelines. The authors review the current evidence on prevalence, natural history, role of treatment, and surveillance and screening imaging and highlight the areas for further research.

BACKGROUND: The best management of unruptured intracranial aneurysms (UIAs) remains unknown, despite multiple observational studies. A randomized trial (RCT) is in order. Yet, a National Institute Neurological Disorders and Stroke workshop has once again proposed to use prospective observational studies (POS) of large databases to address such problems.
METHODS: We review the historical misconceptions that have been associated with observations of UIAs and their treatments. We critically examine some recent methods that have been proposed to address shortcomings of observational studies. We finally review the ethical principles underlying the use of trial methods in the care of patients.
RESULTS: Replacing RCTs with POS submits patients to management options that have never been proven beneficial, while making them involuntary research subjects of studies that are inevitably biased. A science of practice cannot be an outsider\'s examination of the behavior of clinicians incapable of questioning their practice. The thesis we propose is that a science of practice must not only eventually determine what best practice will be; It must engage agents involved in medical practice to transparently reveal the uncertainty that calls for management options to be offered under the guidance of declared and controlled care research, to optimize patient outcomes in spite of the uncertainty.
CONCLUSIONS: To use POS rather than RCTs in medical practice is to renege on scientific and ethical principles that characterize modern medicine. Instead, we must learn to integrate care research into our practice to provide optimal medical care in real time.