The unruptured intracranial aneurysm treatment score: a multidisciplinary consensus

Imaging of Intracranial Aneurysms: A Review of Standard and Advanced Imaging Techniques

The treatment of intracranial aneurysms is dictated by its risk of rupture in the future. Several clinical and radiological risk factors for aneurysm rupture have been described and incorporated into prediction models. Despite the recent technological advancements in aneurysm imaging, linear length and visible irregularity with a bleb are the only radiological measure used in clinical prediction models. The purpose of this article is to summarize both the standard imaging techniques, including their limitations, and the advanced techniques being used experimentally to image aneurysms. It is expected that as our understanding of advanced techniques improves, and their ability to predict clinical events is demonstrated, they become an increasingly routine part of aneurysm assessment. It is important that neurovascular specialists understand the spectrum of imaging techniques available.

Effect of the aspect ratio and wall heterogeneities on the mechanical behaviour of the aneurysm wall: Experimental investigation on phantom arteries

The management of unruptured intracranial aneurysms (UIA) involves assessing the risk of rupture, which requires a thorough understanding of risk factors such as the geometric characteristics of the neck (neck size) or local structural heterogeneities. This study explores the impact of neck size on the rupture risk of the aneurysmal sac and examines how local heterogeneities, such as calcifications or variations in tissue composition, influence the mechanical response of the wall of a saccular aneurysm during the insertion of an innovative arterial wall deformation device (DDP). The results reveal that high aspect ratios (AR) are associated with increased hemodynamic stress, thereby raising the risk of rupture. Additionally, this study provides valuable insights into the complex relationship between tissue heterogeneity, especially calcifications, and the mechanical response of aneurysm walls to mechanical stimuli. It appears that local heterogeneities weaken the integrity of the arterial wall, thus increasing the potential for rupture. Finally, although the DDP is not intended to treat intracranial aneurysms (IA), it could prove to be a relevant tool for deepening the understanding of their rupture mechanisms.

Intracranial Aneurysms in Autosomal Dominant Polycystic Kidney Disease: A Practical Approach to Screening and Management

Autosomal dominant polycystic kidney disease (ADPKD), the most prevalent genetic kidney disorder, is characterized by diffuse kidney cysts, hypertension, and progressive kidney function decline, often leading to kidney failure by the age of 60 years. Compared with the general population, patients with ADPKD have an increased risk for development of saccular intracranial aneurysms (IAs), which can lead to intracranial bleeding and result in significant disability and mortality. Of both modifiable and nonmodifiable risk factors, the most significant is a family history of IAs or aneurysm rupture. Other contributing factors include hypertension, cigarette smoking, age, and sex. Most IAs currently detected during screening tests are small and located in the anterior circulation. Intracranial aneurysms can be manifested with thunderclap headache, which may be indicative of subarachnoid hemorrhage. Less commonly, IAs cause symptoms related to mass effect with focal neurologic deficits. Subarachnoid hemorrhage is particularly concerning, given its high case-fatality rate, which remains around 35% despite advances in neurologic care. Therefore, control of risk factors, early detection, and treatment when indicated are important to prevent adverse outcomes. Screening for IAs in ADPKD remains controversial and can be approached either universally (screening of all ADPKD patients) or selectively (screening of high-risk patients). The preferred imaging modality is brain magnetic resonance angiography without contrast enhancement or alternatively computed tomography angiography. This review provides a practical guide for medical teams managing patients with ADPKD, detailing the characteristics of IAs and their associated symptoms. It presents an algorithm for risk assessment and screening along with recommendations for treatment and follow-up care.

Impact of workflow variability on image-based intracranial aneurysm hemodynamics

The interplay between intracranial aneurysm progression and hemodynamics motivates the application of image-based blood flow quantification, providing potential for the identification of high-risk aneurysms, treatment planning, and implant optimization. However, uncertainties arise throughout the interdisciplinary process, from medical imaging to parameter evaluation. This study systematically analyzes uncertainty globally, at individual workflow steps and for potential interactions. Eight factors affecting hemodynamic simulation accuracy - image reconstruction, lumen segmentation, surface smoothing, rheological modeling, inlet/outlet boundary condition, ostium/parent vessel definition - are varied for four representative patient-specific intracranial aneurysms. A total of 1024 transient simulations are evaluated considering twelve hemodynamic parameters to assess marginal and interaction effects. Global uncertainty analysis reveals median absolute deviations of 20.8-25.9 % for maximum velocity (Vmax), 6.8-19.2 % for inflow concentration index (ICI), 10.8-40.8 % for normalized wall shear stress (WSSnorm) and 2.8-48.9 % for low shear area (LSA). Isolated variation demonstrates the highest median deviations for the reconstruction algorithm (Vmax: 4.0-7.0 %, ICI: 6.8-18.9 %, WSSnorm: 13.3-25.1 %, LSA: 2.4-16.0 %), inlet (Vmax: 41.5-52.4 %, ICI: 1.4-8.6 %, WSSnorm: 14.6-28.5 %, LSA: 5.5-93.5 %) and outlet boundary condition (Vmax: 2.0-36.5 %, ICI: 0.6-39.9 %, WSSnorm: 2.4-83.2 %, LSA: 1.9-53.5 %). Lowest median deviations are found for rheological modeling and surface smoothing. Only minor interaction effects are observed between the reconstruction algorithm and inlet definition, as well as between inlet and outlet definitions. This study identifies pivotal variables essential for consistent hemodynamic quantification of intracranial aneurysms. Minimal interaction effects validate the isolated analysis of influencing factors in the majority of cases.

Impact of lifetime and current smoking exposure on the rupture status, number, and size of intracranial aneurysms

BACKGROUND

Quantitative data on the impact of smoking on genesis of intracranial aneurysms (IA) is sparse. We aimed to analyze the association between lifetime and current smoking exposure and IA characteristics.

METHODS

In this prospective observational cohort study (07/2016-01/2023, n = 918), all patients or next of kin filled out the questionnaire for assessment of smoking habits including the status (no/former/current) and consumption level (heavy vs light current smoker [≥/<10 cigarettes/day], and lifetime exposure in pack-years). The study endpoints were the ruptured status, size, and presence of multiple IA.

RESULTS

The distribution of non-, former, light, and heavy smokers was 23.2 %, 25.6 %, 11.2 % and 40 % respectively. The median lifetime smoking exposure was 20 pack-years. Current smokers were at higher risk of presenting with ruptured (adjusted odds ratio [aOR]=1.71, 95 % confidence interval [CI]=1.29-2.26, p < 0.0001), large (≥7 mm, aOR=1.41, 95 % CI=1.05-1.89, p = 0.022) and multiple IA (aOR=1.34, 95 % CI=1.01-1.77, p = 0.045). In the subgroup analysis among ever smokers, heavy smoking additionally increased the risk of IA rupture (aOR=1.83, 95 % CI=1.33-2.50, p < 0.0001) and larger size (aOR=1.65, 95 % CI=1.19-2.30, p = 0.003). Finally, longer history of smoking (>20 pack-years) was related to higher probability of multiple (aOR=1.61, 95 % CI=1.21-2.13, p = 0.001) and large IA (aOR=1.40, 95 % CI=1.04-1.87, p = 0.025).

CONCLUSIONS

Our data underline the role of smoking in IA genesis, and the importance of smoking cessation for rupture prevention. Current and particularly heavy smoking increases the risk of IA rupture, whereas the chronic exposure over years more likely results in the development of multiple and large IA.

The Role and Reliability of Unruptured Intracranial Aneurysm Treatment Score in Decision-making in Surgical Indications for Unruptured Intracranial Aneurysms Based on the Results at a Japanese Single Center

To clarify the role and reliability of unruptured intracranial aneurysm treatment score in the treatment indications of unruptured intracranial aneurysm for Japanese patients, we performed a retrospective comparative analysis of our actual decision-making and unruptured intracranial aneurysm treatment score judgment. The unruptured intracranial aneurysm treatment score was applied to each of 208 Japanese patients with diagnosis of unruptured intracranial aneurysm for a year. The patients included were classified into 4 groups by integrating actual decisions with the scoring of unruptured intracranial aneurysm treatment score. Of 94 patients treated, unruptured intracranial aneurysm treatment score recommended repair for 64 (68.1%, "appropriately treated") and observation for 5 (5.3%, "possible over-treated"). Among 114 patients under observation, unruptured intracranial aneurysm treatment score recommended repair for 19 (16.7%, "possible under-treated") and observation for 29 (25.4%, "appropriately conservative"). In the remaining 91 patients judged as "not definitive" by the unruptured intracranial aneurysm treatment score, 66 (72.5%) were determined as conservative follow-up. From the perspective of the unruptured intracranial aneurysm treatment score, its sensitivity and specificity were 85.3% and 88.6%, respectively. Our findings suggest that in Japanese patients with unruptured intracranial aneurysm, unruptured intracranial aneurysm treatment score is a reliable tool for guiding treatment decisions for unexpertized clinicians; however, the final judgment should be made by a trained neurosurgeon, especially in cases categorized as not definitive.

Machine Learning Algorithms to Predict the Risk of Rupture of Intracranial Aneurysms: a Systematic Review

PURPOSE

Subarachnoid haemorrhage is a potentially fatal consequence of intracranial aneurysm rupture, however, it is difficult to predict if aneurysms will rupture. Prophylactic treatment of an intracranial aneurysm also involves risk, hence identifying rupture-prone aneurysms is of substantial clinical importance. This systematic review aims to evaluate the performance of machine learning algorithms for predicting intracranial aneurysm rupture risk.

METHODS

MEDLINE, Embase, Cochrane Library and Web of Science were searched until December 2023. Studies incorporating any machine learning algorithm to predict the risk of rupture of an intracranial aneurysm were included. Risk of bias was assessed using the Prediction Model Risk of Bias Assessment Tool (PROBAST). PROSPERO registration: CRD42023452509.

RESULTS

Out of 10,307 records screened, 20 studies met the eligibility criteria for this review incorporating a total of 20,286 aneurysm cases. The machine learning models gave a 0.66-0.90 range for performance accuracy. The models were compared to current clinical standards in six studies and gave mixed results. Most studies posed high or unclear risks of bias and concerns for applicability, limiting the inferences that can be drawn from them. There was insufficient homogenous data for a meta-analysis.

CONCLUSIONS

Machine learning can be applied to predict the risk of rupture for intracranial aneurysms. However, the evidence does not comprehensively demonstrate superiority to existing practice, limiting its role as a clinical adjunct. Further prospective multicentre studies of recent machine learning tools are needed to prove clinical validation before they are implemented in the clinic.

Artificial intelligence in neurovascular decision-making: a comparative analysis of ChatGPT-4 and multidisciplinary expert recommendations for unruptured intracranial aneurysms

In the multidisciplinary treatment of cerebrovascular diseases, specialists from different disciplines strive to develop patient-specific treatment recommendations. ChatGPT is a natural language processing chatbot with increasing applicability in medical practice. This study evaluates ChatGPT's ability to provide treatment recommendations for patients with unruptured intracranial aneurysms (UIA). Anonymized patient data and radiological reports of 20 patients with UIAs were provided to GPT-4 in a standardized format and used to generate a treatment recommendation for different clinical scenarios. GPT-4 responses were evaluated by a multidisciplinary panel of specialists by means of the Likert scale and subsequently benchmarked against the Unruptured Intracranial Aneurysm Treatment Score (UIATS) as well as the actual treatment decision made by the multidisciplinary institutional neurovascular board (INVB). Agreement between expert raters was measured using linear weighted Fleiss-Kappa coefficient. GPT-4 analyzed individual pathological features of the radiological reports and formulated a corresponding assessment for each aspect. None of the recommendations generated reflected evidence of factual hallucination, although in 25% of the case studies no specific recommendation could be derived from the GPT-4 responses. The expert panel rated the overall quality of the GPT-4 recommendations with a median of 3.4 out of 5 points. The GPT-4 recommendations were congruent with those of the INBI in 65% of cases. Interrater reliability among experts showed moderate to low agreement in the assessment of AI-assisted decision making. GPT-4 appears to be able to process clinical information about UIAs and generate treatment recommendations. However, the level of ambiguity and the utilization of scientific evidence in the recommendations are not yet patient/case specific enough to substitute the decision-making of a multidisciplinary neurovascular board. A prospective evaluation of GPT-4 competence as a companion in decision-making panels is deemed necessary.

Assessment of the stability of intracranial aneurysms using a deep learning model based on computed tomography angiography

PURPOSE

Assessment of the stability of intracranial aneurysms is important in the clinic but remains challenging. The aim of this study was to construct a deep learning model (DLM) to identify unstable aneurysms on computed tomography angiography (CTA) images.

METHODS

The clinical data of 1041 patients with 1227 aneurysms were retrospectively analyzed from August 2011 to May 2021. Patients with aneurysms were divided into unstable (ruptured, evolving and symptomatic aneurysms) and stable (fortuitous, nonevolving and asymptomatic aneurysms) groups and randomly divided into training (833 patients with 991 aneurysms) and internal validation (208 patients with 236 aneurysms) sets. One hundred and ninety-seven patients with 229 aneurysms from another hospital were included in the external validation set. Six models based on a convolutional neural network (CNN) or logistic regression were constructed on the basis of clinical, morphological and deep learning (DL) features. The area under the curve (AUC), accuracy, sensitivity and specificity were calculated to evaluate the discriminating ability of the models.

RESULTS

The AUCs of Models A (clinical), B (morphological) and C (DL features from the CTA image) in the external validation set were 0.5706, 0.9665 and 0.8453, respectively. The AUCs of Model D (clinical and DL features), Model E (clinical and morphological features) and Model F (clinical, morphological and DL features) in the external validation set were 0.8395, 0.9597 and 0.9696, respectively.

CONCLUSIONS

The CNN-based DLM, which integrates clinical, morphological and DL features, outperforms other models in predicting IA stability. The DLM has the potential to assess IA stability and support clinical decision-making.

Differences between real-world and score-based decision-making in the microsurgical management of patients with unruptured intracranial aneurysms

BACKGROUND

Management of unruptured intracranial aneurysms (UIAs) is complex, balancing the risk of rupture and risk of treatment. Therefore, prediction scores have been developed to support clinicians in the management of UIAs. We analyzed the discrepancies between interdisciplinary cerebrovascular board decision-making factors and the results of the prediction scores in our cohort of patients who received microsurgical treatment of UIAs.

METHODS

Clinical, radiological, and demographical data of 221 patients presenting with 276 microsurgically treated aneurysms were collected, from January 2013 to June 2020. UIATS, PHASES, and ELAPSS were calculated for each treated aneurysm, resulting in subgroups favoring treatment or conservative management for each score. Cerebrovascular board decision-factors were collected and analyzed.

RESULTS

UIATS, PHASES, and ELAPSS recommended conservative management in 87 (31.5%) respectively in 110 (39.9%) and in 81 (29.3%) aneurysms. The cerebrovascular board decision-factors leading to treatment in these aneurysms (recommended to manage conservatively in the three scores) were: high life expectancy/young age (50.0%), angioanatomical factors (25.0%), multiplicity of aneurysms (16.7%). Analysis of cerebrovascular board decision-making factors in the "conservative management" subgroup of the UIATS showed that angioanatomical factors (P=0.001) led more frequently to surgery. PHASES and ELAPSS subgroups "conservative management" were more frequently treated due to clinical risk factors (P=0.002).

CONCLUSIONS

Our analysis showed more aneurysms were treated based on "real-world" decision-making than recommended by the scores. This is because these scores are models trying to reproduce reality, which is yet not fully understood. Aneurysms, which were recommended to manage conservatively, were treated mainly because of angioanatomy, high life expectancy, clinical risk factors, and patient's treatment wish. The UIATS is suboptimal regarding assessment of angioanatomy, the PHASES regarding clinical risk factors, complexity, and high life expectancy, and the ELAPSS regarding clinical risk factors and multiplicity of aneurysms. These findings support the need to optimize prediction models of UIAs.

An In vivo Pilot Study to Estimate the Swelling of the Aneurysm Wall Rabbit Model Generated with Pulsed Fluid Against the Aneurysm Wall

PURPOSE

This study addresses the critical issue of evaluating the risk of rupture of unruptured intracranial aneurysms (UIAs) through the assessment of the mechanical properties of the aneurysm wall. To achieve this, an original approach based on the development of an in vivo deformation device prototype (DDP) of the vascular wall is proposed. The DDP operates by pulsing a physiological fluid onto the vascular wall and measuring the resulting deformation using spectral photon counting computed tomography (SPCCT) imaging.

METHODS

In this preliminary study conducted on a rabbit animal model, an aneurysm was induced on the carotid artery, followed by deformation of the aneurysm sac wall using the DDP. The change in luminal volume of the aneurysm sac induced by the deformation of the vascular wall was then quantified.

RESULTS

The initial experimental results demonstrated an increase in the luminal volume of the aneurysm sac in relation to the increased flow rate of the fluid pulsed by the DDP onto the arterial wall. Measurement of the pressure generated by the DDP in relation to the different flow rate values imposed by the pulsation system revealed experimental values of the same order of magnitude as dynamic blood pressure. Furthermore, theoretical pressure values on the deformed area, calculated using Euler's theorem, appeared to be correlated with experimental pressure measurements.

CONCLUSION

This equivalence between theory and experiment is a key element in the use of the DDP for estimating the mechanical properties of the vascular wall, particularly for the use of finite element models to characterise the stress state of the deformed vascular wall. This preliminary work thus presents a novel, innovative, and promising approach for the evaluation and management of the risk of rupture of unruptured intracranial aneurysms.

Stroke and Pulmonary Thromboembolism Complicating a Kissing Aneurysm in the M1 Segment of the Right MCA

Background/Objectives: Kissing aneurysms, a rare and intriguing cerebrovascular anomaly, challenge even the most advanced neurosurgical techniques. These lesions, characterized by two intimately apposed aneurysms with shared arterial walls, often masquerade as single, irregular aneurysms. This report documents a case of ruptured kissing aneurysms in the M1 segment of the right middle cerebral artery (MCA), complicated by ischemic stroke and pulmonary thromboembolism (PTE)-a convergence of severe complications rarely encountered. The case underscores the importance of precise diagnostics, innovative surgical strategies, and multidisciplinary care. Methods: A 55-year-old female presented with subarachnoid hemorrhage, confirmed by advanced imaging to arise from ruptured kissing aneurysms in the M1 segment of the right MCA. Surgical intervention via a right frontotemporal craniotomy and microsurgical clipping achieved definitive aneurysmal exclusion. Postoperatively, the patient experienced ischemic stroke and PTE, necessitating dynamic adjustments in anticoagulation therapy, intensive care, and rehabilitation protocols. Results: The dual aneurysms were successfully clipped, as confirmed by intraoperative and postoperative imaging. Despite developing significant complications, including left-sided motor deficits and PTE, a carefully orchestrated treatment strategy enabled the patient's full recovery, with marked neurological and systemic improvement by her three-month follow-up. This favorable outcome highlights the resilience of a multidisciplinary approach in navigating such high-risk scenarios. Conclusions: This case showcases the formidable challenges of managing kissing aneurysms, particularly when compounded by stroke and PTE. It emphasizes the transformative role of cutting-edge imaging and surgical techniques in achieving successful outcomes. By illustrating how precision medicine and collaborative care can overcome rare and complex cases, this report contributes valuable insights to the evolving field of cerebrovascular surgery and postoperative management.

Comparison between ruptured anterior choroidal artery aneurysms and ruptured intracranial aneurysms in other locations in relation to aneurysm dimensions at rupture

PURPOSE

It was noticed that anterior choroidal artery (AChoA) aneurysms appear to rupture at relatively smaller sizes compared with aneurysms in other intracranial locations, based on anecdotal clinical experience. We therefore aimed to compare ruptured AChoA aneurysms with other ruptured aneurysms in other intracranial locations, pertaining to aneurysm dimensions. This may help in finding out if the rupture risk stratification, based on the amalgamation of aneurysms of multiple locations in one group, precisely estimates aneurysm rupture risk.

METHODS

255 ruptured intracranial aneurysms, which underwent assessment with catheter angiography with 3D reconstruction, in a single tertiary center between January 2000 and December 2023, were included. 6 aneurysm dimensions were compared.

RESULTS

Statistically significant larger aneurysm maximum diameter, height, width and size ratio (SR) of the ruptured posterior communicating artery (PCOMM) aneurysms were identified when compared with ruptured AChoA aneurysms. No statistically significant difference in the aneurysm maximum diameter, height and width between the ruptured AChoA and ruptured anterior cerebral artery (ACA), anterior communicating artery (Acom), pericallosal artery and basilar tip aneurysms was found. AChoA aneurysms appear to rupture at a relatively small size, which is comparable to other aneurysm locations that are often grouped into different categories in rupture risk stratification.

CONCLUSION

More detailed location-specific rupture risk estimation may be needed. The combination of multiple intracranial aneurysm locations into a single category for risk stratification may not reflect the true aneurysm size at rupture for some aneurysms.

Hemodynamic Characteristics in Ruptured and Unruptured Intracranial Aneurysms: A Prospective Cohort Study Utilizing the AneurysmFlow Tool

BACKGROUND AND PURPOSE

Hemodynamic factors significantly influence the onset, progression, and rupture of intracranial aneurysms (IAs). Current rupture risk prediction scores focus primarily on the clinical, anatomic, and morphologic aspects. This study aimed to investigate the hemodynamic characteristics differences between ruptured and unruptured IAs.

MATERIALS AND METHODS

Conducted from July 2021 to July 2022, this prospective cohort study involved patients with ruptured and unruptured IAs undergoing DSA. Hemodynamic characteristics were assessed by using the AneurysmFlow tool. Hemodynamic, clinical, anatomic, and morphologic parameters were compared between ruptured and unruptured IA groups.

RESULTS

The study included 127 patients with 135 aneurysms (67 ruptured, 68 unruptured). Complex flow patterns (type 3 and 4) were observed more frequently in ruptured aneurysms compared with unruptured aneurysms (OR, 5.57; 95% CI, 2.49-12.45; P < .001) in univariate analysis, and were also more common in unruptured aneurysms associated with daughter sac features (P = .015). The mean aneurysm flow amplitude (MAFA) was lower in ruptured aneurysms, and associated with lower flow velocity in the parent artery related to vasospasm. MAFA in the aneurysmal dome or any additional daughter sacs was lowest compared with other regions inside the aneurysms. The technical failure rate of AneurysmFlow measurements was 8.5% (12 of 139 patients). Additionally, hypertension (OR, 0.42; 95% CI, 0.30-0.54; P < .001), bifurcation location (anterior communicating artery/anterior cerebral artery/MCA/posterior communicating artery/posterior circulation) (OR, 0.17; 95% CI, 0.05-0.29; P = .005), and irregular shape (OR, 0.19; 95% CI, 0.05-0.35; P = .012) were identified as independently associated with rupture.

CONCLUSIONS

Complex flow patterns identified on the AneurysmFlow tool are significantly more common in ruptured and unruptured aneurysms associated with daughter sac features. The lowest MAFA in the aneurysmal dome and daughter sacs likely indicates specific pathophysiologic changes within the aneurysm wall associated with rupture incidence. Hypertension, bifurcation location, and an irregular shape are independently associated with the risk of rupture. Further multicenter studies with larger sample sizes are needed to validate these findings.

Open Microsurgical Versus Endovascular Management of Unruptured and Ruptured Brain Aneurysms

Open microsurgical and endovascular techniques are the 2 primary strategies for treating intracranial aneurysms. Microsurgical clipping and adjuvant technical maneuvers are well-established techniques with a track record for high occlusion rates and durable repairs. Endovascular, endosaccular, and extrasaccular therapies are associated with lower peri-procedural morbidity but with generally higher rates of retreatment. We discuss key clinical and anatomic considerations in treatment decision-making and compare the risks and benefits of microsurgical vs endovascular treatment within each context.

Circulating collagen breakdown products as a biomarker for presence and instability of human intracranial aneurysms

INTRODUCTION

There is an unmet need for improved detection of intracranial aneurysms (IAs) and distinction between stable and unstable (high rupture risk) IAs. Within the IA wall, synthesis and degradation of type I collagen as the main molecular constituent balance each other to maintain IA stability. We hypothesized that collagen breakdown products could serve as molecular markers for IA presence and instability.

PATIENTS AND METHODS

This prospective, cross-sectional, single-center study included patients with unstable (growing/symptomatic/ruptured) and stable IAs and controls. We determined C-telopeptide (CTx) and c-terminal telopeptide (ICTP) as breakdown products of type I collagen in arterial and venous blood.

RESULTS

We included 107 participants with IAs (52 stable/44 unstable) and 41 controls. The correlation between intra-aneurysmal and venous levels was r = 0.63 (p < 0.001) for ICTP, r = 0.55 (p = 0.001) for CTx. The odds of harboring an IA were five times higher for participants with high compared to low venous levels of collagen breakdown products (ICTP: odds ratio (OR) 4.9 (95% CI 1.1-22.7); CTx: OR 5.3 (95% CI 1.4-20.0)). The OR for having an unstable IA was 9.3 (95% CI 2.1-41.5) for patients with high compared to low venous ICTP levels. The area under the curve for ICTP levels as a marker for IA instability was 0.75.

DISCUSSION AND CONCLUSION

Increased levels of venous collagen breakdown products, especially ICTP levels, could serve as a biomarker for IA presence and instability and complement current data for management of unruptured IAs on an individual patient level. Future studies with longitudinal data are needed to validate ICTP as a biomarker for high risk IAs.

Multiple omics reveal link between the microbiota-gut-brain axis and intracranial aneurysm rupture

Intracranial aneurysms (IAs) are benign cerebrovascular maladies characterized by wall dilatation in the intracranial arteries. Nevertheless, spontaneous aneurysmal rupture can cause a life-threatening spontaneous subarachnoid hemorrhage (SAH). Emerging evidence indicates potential associations between gut dysbiosis and IAs pathogenesis, though the relationship with IA rupture remains unclear. This research analyzed 124 fecal samples for microbiomics and 160 for metabolomics, with the discovery and validation sets established for cross-validation. We identified differential gut microbiota and metabolites associated with ruptured intracranial aneurysms (RIAs) and developed a superior risk assessment model. Subsequent integrative analyses and validation revealed a significant link between disrupted unsaturated fatty acid and essential amino acid metabolic pathways and IA rupture, driven by alterations in gut microbiota. This study underscores the potential association between the gut-brain axis and IA rupture, while also highlighting gut microbiota dysbiosis as a potential risk factor for IA rupture and providing biomarkers for assessment.

The MARVIN Hypothesis: Linking Unhealthy Lifestyles to Intracranial Aneurysm Rupture Risk and Clinical Prognosis

Background and Objectives: The rising incidence of modifiable lifestyle risk factors and cardiovascular diseases, driven by poor diet, inactivity, excessive alcohol use, and smoking, may influence the development and rupture of intracranial aneurysms (IA). This study aimed to examine the impact of lifestyle-related and cardiovascular risk factors on IA rupture and patient outcomes. Materials and Methods: We developed the "MARVIN" (Metabolic and Adverse Risk Factors and Vices Influencing Intracranial Aneurysms) model and conducted a retrospective analysis of 303 patients with 517 IAs, treated between 2007 and 2020. Of these, 225 patients were analyzed for rupture status and 221 for clinical outcomes. The analysis focused on hypertension, diabetes, hypercholesterolemia, vascular diseases, nicotine and alcohol abuse, obesity, aneurysm rupture status, and clinical outcomes. Logistic regression was used to evaluate the impact of these risk factors. Results: Among those with risk factors, 24.9% (56/225) and 25.3% (56/221) had one, 32.0% (72/225) and 30.8% (68/221) had two, 20.0% (45/225) and 20.4% (45/221) had three, 12.0% (27/225) and 12.2% (27/221) had four, 4.0% (9/225) and 4.1% (9/221) had five, 0.9% (2/225) had six in both groups, and 0.4% (1/225) and 0.5% (1/221) had seven risk factors, respectively. Strong relationships were found between lifestyle-related vascular risk factors, indicating multiple comorbidities in patients with unhealthy habits. Smokers with ruptured aneurysms had higher WFNS (World Federation of Neurosurgical Societies) scores, but nicotine abuse did not affect long-term outcomes. The most significant predictors for poor outcomes were WFNS score and age, while age and a history of vascular diseases were protective against rupture. Despite the high prevalence of modifiable risk factors, they did not significantly influence rupture risk. Conclusions: The findings suggest a need for multifactorial risk assessment strategies in managing IA patients. Future studies with larger cohorts are required to confirm these results and better understand IA progression.

Microsurgical clipping of unruptured intracranial aneurysms: Clinical and radiological outcomes

BACKGROUND AND OBJECTIVES

The prevalence of unruptured intracranial aneurysms is 1-3%. The annual rupture rate increases in patients with multiple aneurysms that presented a previous hemorrhage from another aneurysm.

OBJECTIVES

To evaluate outcomes of clipping unruptured aneurysms, comparing patients with single or multiple aneurysms clipped, describe the complications related to surgery and to identify risk factors predicting an unfavorable outcome.

MATERIALS AND METHODS

Retrospective study including patients who underwent clipping of unruptured aneurysms between 2020-2023 at our center. Occlusion rate, complications, and functional outcome were analyzed. Risk factors for poor prognosis are identified using univariate model.

RESULTS

82 patients with 114 aneurysms were treated with microsurgery. Multiple aneurysms were clipped in 22 patients. A mini-open approach was used in 86,5% of cases. Complete occlusion in angio3D was found in 78.6% of clipped aneurysms. Complication rate was 12.2%, including asymptomatic cases. Mortality was 0%. The probability of 1 point mRS worsening was 7.3% and 2 or more points was 1.2%, with a good functional outcome in 98.9%. Clipping multiple aneurysms, miniopen approaches, or surgery in patients with previous subarachnoid hemorrhage did not increase the risk of complications. Posterior circulation aneurysms surgery increased the risk of ischemia.

CONCLUSIONS

The management for unruptured intracranial aneurysms should be multimodal and based on clinical and radiological outcomes. Microsurgery is a valid and safe technique, with 0% mortality and bleeding rates and 1,2% rate of severe morbidity in our series.

Sensitivity of the Unruptured Intracranial Aneurysm Treatment Score (UIATS) to detect aneurysms at high-risk of rupture: Retrospective analysis in a cohort of 346 patients with a proven subarachnoid hemorrhage

INTRODUCTION

The aim of this study was to assess the capability of the Unruptured Intracranial Aneurysm Treatment Score (UIATS) to discriminate unruptured intracranial aneurysms (UIAs) at high risk for subarachnoid hemorrhage (aSAH).

MATERIAL AND METHOD

During the period from January 2012 to December 2022, we included all consecutive adult patients admitted to our institution for an aSAH caused by the rupture of a saccular IA. The patient-related, aneurysm-related and treatment-related risk factors considered by UIATS were retrieved from medical records. After UIATS calculation for all ruptured IAs in the cohort, patients were categorized as "true positives (TP)" if UIATS would have (appropriately) oriented the management toward treatment, whereas patients for whom the UIATS would have (inappropriately) recommended observation were categorized as "false negatives (FN)". Patients for whom UIATS was inconclusive were categorized as "undetermined (UND)". Sensitivity of the UIATS (Se UIATS) was calculated by using the following formula: TP/(TP + FN).

RESULTS

A total of 346 patients (253 women, 73%; mean age = 56 ± 1.45 years) were incorporated into the final analysis. There were 140 T P (40%), 79 F N (23%) and 127 UND (37%), leading to a Se UIATS of 63.9% (CI 58.3-69.5). Cumulatively, the UIATS failed to provide an appropriate recommendation in 60% of the entire cohort.

CONCLUSION

By retrospectively applying the UIATS in a cohort of ruptured IAs, our study emphasizes how vulnerable the UIATS can be. Even if the UIATS suggests conservative management, clinicians should inform patients that there is still a small risk of rupture.

Microsurgical Clipping of Unruptured Middle Cerebral Artery Bifurcation Aneurysms: A Single-Center Experience

BACKGROUND/OBJECTIVES

Microsurgical clipping has traditionally been considered a standard treatment for middle cerebral artery (MCA) aneurysms. Recently, a caseload reduction related to improved endovascular treatment options has occurred in cerebrovascular neurosurgery. Therefore, studies that report the clinical and radiological outcomes after clipping are highly warranted.

METHODS

Patients with an unruptured MCA bifurcation aneurysm, who were surgically treated at the Department of Neurosurgery in Linz between 2002 and 2019, were included in this study. Clinical and radiological outcome parameters were evaluated for each patient.

RESULTS

Overall, 272 patients were eligible for inclusion. Complete aneurysm occlusion was demonstrated in 266 (99.3%) of the 268 (98.5%) patients who underwent postoperative digital subtraction angiography. In six (2.2%) patients, a permanent new neurological deficit (pNND) persisted after treatment. Intraoperative aneurysm rupture was a significant factor (p = 0.0049) in the logistic regression. At the last follow-up, only two patients (0.7%) had an unfavorable outcome (mRS > 2). More recent surgeries were associated with fewer cases of pNND (p = 0.009). A transient new neurological deficit occurred in 13 patients (4.8%), with aneurysm size being a significant risk factor (p = 0.009). Surgical site infections were reported in four patients (1.5%), with patient age (p = 0.039) and time (p = 0.001) being significant factors. Two patients died (0.7%) perioperatively and two patients (0.7%) needed a retreatment in the long-term follow-up.

CONCLUSIONS

The findings indicate that microsurgical clipping is a safe procedure with minimal need for retreatment. It achieves a high occlusion rate while maintaining a very low rate of adverse outcomes. Continuous intraoperative enhancements over time have contributed to a progressive improvement in clinical outcomes in recent years. This trend is exemplified by the absence of detectable pNND in the era of ICG angiography. Consequently, these data support the conclusion that microsurgical clipping should still be considered an appropriate treatment option for unruptured MCA bifurcation aneurysms.

Association between preventive treatment for unruptured intracranial aneurysms and incident dementia: a nationwide population-based cohort study

Preventive treatments for unruptured intracranial aneurysms (UIAs) are used worldwide. However, the long-term effects to cognition have been underestimated. Using representative sample data from the National Health Insurance Service-Senior Cohort database, we compared cumulative risk of incident dementia between two groups: (1) treatment versus observation group, and (2) within the treatment group (surgical versus endovascular treatment). Cox proportional hazard ratios were estimated after applying one-to-one propensity score matching. Subgroup analyses were conducted to investigate interactions between treatment effects and sex, age and history of stroke, respectively. After matching, 3,763 participants were included in each group. The 10-year incidence rates of dementia were 9.82 and 8.68 per 1,000 person-years in the treatment and observation groups, respectively (HR: 1.11, 95% CI: 0.90-1.38, P = 0.33). Furthermore, the risk of incident dementia was not different between the surgical and endovascular treatment groups (HR: 0.98, 95% CI: 0.70-1.37, P = 0.91). In the subgroup analysis, surgical treatment was associated with an increased risk of developing dementia, particularly among male patient (HR: 2.34, 95% CI: 1.04-5.28). Preventive treatment of UIAs appears acceptable in terms of long-term effects to cognition. However, further researches are strongly required to identify the high risk patients of development of dementia.

Intracranial Aneurysms and Cerebral Small Vessel Disease: Is There an Association between Large- and Small-Artery Diseases?

Background/Objectives: Intracranial aneurysms (IAs) may be connected to interactions between large and small intracranial vessels. We aimed to investigate the association between IAs and cerebral small-vessel disease (CSVD) and assess CSVD impact on IA patient management. Methods: This retrospective study analyzed clinical data and MRI features of CSVD in 192 subarachnoid hemorrhage (SAH) patients: 136 with incidental IA, 147 with severe CSVD without SAH/IA, and 50 controls without SAH, IA, or severe CSVD. MRI assessments followed the Standards for Reporting Vascular Changes on Neuroimaging (STRIVE), with a total burden of small-vessel disease (TBSVD) score calculated. Statistical analyses included forward selection and binary logistic regression. Results: TBSVD differed significantly across groups (p < 0.001), except between SAH and IA groups (p = 0.8). Controls had the lowest TBSVD (1.00; 1.22 ± 0.996), followed by SAH (2.00; 2.08 ± 1.013) and IA groups (2.00; 2.04 ± 1.141), with the highest in the CSVD group (1.00; 1.22 ± 0.996). White-matter hyperintensity (WMH) patterns varied with IA rupture status (p = 0.044); type A was prevalent in SAH patients and type D in the IA group. Incorporating MRI CSVD features and TBSVD into risk assessments did not enhance IA prediction or outcome models. Conclusions: IA patients exhibit a higher CSVD burden than controls, suggesting a link between small and large intracranial vessels. WMH patterns distinguish between ruptured and unruptured IA patients, offering potential markers for IA rupture risk assessment and signaling a paradigm shift in understanding IAs and CSVD.

Assessment of Interrater Reliability and Accuracy of Cerebral Aneurysm Morphometry Using 3D Virtual Reality, 2D Digital Subtraction Angiography, and 3D Reconstruction: A Randomized Comparative Study

BACKGROUND/OBJECTIVES

Detailed morphometric analysis of an aneurysm and the related vascular bifurcation are critical factors when determining rupture risk and planning treatment for unruptured intracranial aneurysms (UIAs). The standard visualization of digital subtraction angiography (DSA) and its 3D reconstruction on a 2D monitor provide precise measurements but are subject to variability based on the rater. Visualization using virtual (VR) and augmented reality platforms can overcome those limitations. It is, however, unclear whether accurate measurements of the aneurysm and adjacent arterial branches can be obtained on VR models. This study aimed to assess interrater reliability and compare measurements between 3D VR, standard 2D DSA, and 3D DSA reconstructions, evaluating the reliability and accuracy of 3D VR as a measurement tool.

METHODS

A pool of five neurosurgeons performed three individual analyses on each of the ten UIA cases, measuring them in completely immersed 3D VR and the standard on-screen format (2D DSA and 3D reconstruction). This resulted in three independent measurements per modality for each case. Interrater reliability of measurements and morphology characterization, comparative differences, measurement duration, and VR user experience were assessed.

RESULTS

Interrater reliability for 3D VR measurements was significantly higher than for 3D DSA measurements (3D VR mean intraclass correlation coefficient [ICC]: 0.69 ± 0.22 vs. 3D DSA mean ICC: 0.36 ± 0.37, p = 0.042). No significant difference was observed between 3D VR and 2D DSA (3D VR mean ICC: 0.69 ± 0.22 vs. 2D DSA mean ICC: 0.43 ± 0.31, p = 0.12). A linear mixed-effects model showed no effect of 3D VR and 3D DSA (95% CI = -0.26-0.28, p = 0.96) or 3D VR and 2D DSA (95% CI = -0.02-0.53, p = 0.066) on absolute measurements of the aneurysm in the anteroposterior, mediolateral, and craniocaudal dimensions.

CONCLUSIONS

3D VR technology allows for reproducible, accurate, and reliable measurements comparable to measurements performed on a 2D screen. It may also potentially improve precision for measurements of non-planar aneurysm dimensions.

An overview of decision-making in cerebrovascular treatment strategies: Part I - unruptured aneurysms

Introduction

Unruptured intracranial aneurysm treatment has evolved over the last two centuries, starting from the introduction of aneurysm ligation and clipping, up until the inception of endovascular treatment and further advancements in both fields.

Research question

The wide variety of aneurysm presentations and possible treatment modalities, complicates the understanding of decision-making for the treatment of a given aneurysm. The goal of this article is to provide an overview of the best available evidence concerning unruptured intracranial aneurysm decision-making and identify insights and hiatuses, as well as providing a scaffold to surpass the subjectiveness of decision-making.

Materials and methods

A literature review was performed for the most impactful articles on decision-making in unruptured intracranial aneurysm treatment, to provide an overview on current practice.

Results

Two groups of decision-altering factors were identified; patient-related and aneurysm-related factors. A summary is presented of the general evidence, and the influence of age, aneurysmal mass-effect, as well as size, morphological aspects and specific anatomical locations on decision-making.

Discussion and conclusion

Decision-making for an unruptured intracranial aneurysm often comes down to combining these different patient- and aneurysm-related factors. In this paper, an evidence-based overview is provided into these different factors which alter management of unruptured saccular aneurysms.

Development of a mechanical characterisation device for intracranial aneurysms: Calibration on polymeric phantom arteries

Intracranial aneurysm is a major health issue related to biomechanical arterial wall degradation. Currently, no method allows predicting rupture risk based on in vivo quantitative mechanical data. This work is part of a large-scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool, based on the in vivo mechanical characterisation of the aneurysm wall. Thus, the primary objective of the project was to develop a deformation device prototype (DDP) of the artery wall and to calibrate it on polymeric phantom arteries. The deformations induced on the phantom arteries were quantified experimentally using a Digital Image Correlation (DIC) system. The results indicated that the DIC system was able to measure the small displacements generated by the DDP. We also observed that the flow mimicking the blood flow did not significantly disturb the measurements of the artery wall displacement caused by the DDP. Finally, a limit displacement value generated by the DDP was evaluated. This value corresponds to the lowest displacement value detectable by the clinical imaging system that will be tested on animals in the future (Spectral Photon Counting CT).

When microsurgery becomes the only lifesaving resource: An institutional experience treating patients from low-income backgrounds affected by posterior circulation brain aneurysms

BACKGROUND AND OBJECTIVE

Aneurysms of the posterior cerebral circulation constitute a burdensome condition with high mortality and morbidity. In the modern era, there has been a trend toward favoring an endovascular approach over microsurgery for aneurysm cases. Nevertheless, this transition has yet to be mirrored in low-to-middle-income countries where endovascular therapy may not be widely available. Herein, we aim to illustrate our experience treating these challenging conditions in patients from low-income backgrounds and discuss the relevance of the clinical setting in the treatment decision.

METHODS

The authors conducted a retrospective review of the health records of patients who received microsurgical treatment for aneurysms in the posterior circulation, including the basilar artery (BA), posterior cerebral artery (PCA), and posterior inferior cerebellar artery (PICA) in an institution providing treatment to people of low-income backgrounds. Epidemiological data, microsurgical technique, and neurological function were retrieved and analyzed.

RESULTS

Surgical clipping was employed for 12 patients (75% female) harboring 15 aneurysms (87% in the posterior circulation and 62% ruptured at presentation). Aneurysms were predominately located in the BA (69%), followed by the PCA (15%) and PICA (15%). Among neurological complications, 25% of patients developed oculomotor nerve palsy. The mortality rate was 17% owing to complications such as cerebral vasospasm, infarction, and severe intracranial hypertension. At the 6-month follow-up, 90% of patients had a good clinical outcome (modified Rankin scale scores of 0-2).

CONCLUSION

The present case series illustrates the manifest role of microsurgical techniques for posterior circulation aneurysms, particularly in a scenario where endovascular techniques are not easily accessible. Importantly, this clinical setting pressure could exhort trainees to strive for microsurgical mastery and gain a competitive advantage.

Complex intracranial aneurysms: a DELPHI study to define associated characteristics

PURPOSE

Intracranial aneurysms present significant health risks, as their rupture leads to subarachnoid haemorrhage, which in turn has high morbidity and mortality rates. There are several elements affecting the complexity of an intracranial aneurysm. However, criteria for defining a complex intracranial aneurysm (CIA) in open surgery and endovascular treatment could differ, and actually there is no consensus on the definition of a "complex" aneurysm. This DELPHI study aims to assess consensus on variables defining a CIA.

METHODS

An international panel of 50 members, representing various specialties, was recruited to define CIAs through a three-round Delphi process. The panelists participated in surveys with Likert scale responses and open-ended questions. Consensus criteria were established to determine CIA variables, and statistical analysis evaluated consensus and stability.

RESULTS

In open surgery, CIAs were defined by fusiform or blister-like shape, dissecting aetiology, giant size (≥ 25 mm), broad neck encasing parent arteries, extensive neck surface, wall calcification, intraluminal thrombus, collateral branch from the sac, location (AICA, SCA, basilar), vasospasm context, and planned bypass (EC-IC or IC-IC). For endovascular treatment, CIAs included giant size, very wide neck (dome/neck ratio ≤ 1:1), and collateral branch from the sac.

CONCLUSIONS

The definition of aneurysm complexity varies by treatment modality. Since elements related to complexity differ between open surgery and endovascular treatment, these consensus criteria of CIAs could even guide in selecting the best treatment approach.

Turbulent blood flow in a cerebral artery with an aneurysm

Unruptured intracranial aneurysms are common in the general population, and many uncertainties remain when predicting rupture risks and treatment outcomes. One of the cutting-edge tools used to investigate this condition is computational fluid dynamics (CFD). However, CFD is not yet mature enough to guide the clinical management of this disease. In addition, recent studies have reported significant flow instabilities when refined numerical methods are used. Questions remain as to how to properly simulate and evaluate this flow, and whether these instabilities are really turbulence. The purpose of the present study is to evaluate the impact of the simulation setup on the results and investigate the occurrence of turbulence in a cerebral artery with an aneurysm. For this purpose, direct numerical simulations were performed with up to 200 cardiac cycles and with data sampling rates of up to 100,000 times per cardiac cycle. Through phase-averaging or triple decomposition, the contributions of turbulence and of laminar pulsatile waves to the velocity, pressure and wall shear stress fluctuations were distinguished. For example, the commonly used oscillatory shear index was found to be closely related to the laminar waves introduced at the inlet, rather than turbulence. The turbulence energy cascade was evaluated through energy spectrum estimates, revealing that, despite the low flow rates and Reynolds number, the flow is turbulent near the aneurysm. Phase-averaging was shown to be an approach that can help researchers better understand this flow, although the results are highly dependent on simulation setup and post-processing choices.

Time-of-Flight MRA of Intracranial Aneurysms with Interval Surveillance, Clinical Segmentation and Annotations

Intracranial aneurysms (IAs) are present in 2-6% of the global population and can be catastrophic upon rupture with a mortality rate of 30-50%. IAs are commonly detected through time-of-flight magnetic resonance angiography (TOF-MRA), however, this data is rarely available for research and training purposes. The provision of imaging resources such as TOF-MRA images is imperative to develop new strategies for IA detection, rupture prediction, and surgical training. To support efforts in addressing data availability bottlenecks, we provide an open-access TOF-MRA dataset comprising 63 patients, of which 24 underwent interval surveillance imaging by TOF-MRA. Patient scans were evaluated by a neuroradiologist, providing aneurysm and vessel segmentations, clinical annotations, 3D models, in addition to 3D Slicer software environments containing all this data for each patient. This dataset is the first to provide interval surveillance imaging for supporting the understanding of IA growth and stability. This dataset will support computational and experimental research into IA dynamics and assist surgical and radiology training in IA treatment.

Follow-up care compliance among patients diagnosed with unruptured intracranial aneurysms

OBJECTIVES

Periodic imaging follow-up for patients with unruptured intracranial aneurysms (UIA) is crucial, as studies indicate higher rupture risk with aneurysm growth. However, few studies address patient adherence to follow-up recommendations. This study aims to identify compliance rates and factors influencing follow-up adherence.

METHODS

Patients with a UIA were identified from our institution's database from 2011-2021. Follow-up imaging (CT/MR Angiogram) was advised at specific intervals. Patients were categorized into compliant and non-compliant groups based on first-year compliance. Factors contributing to compliance were assessed through multivariate logistic regression. Phone interviews were conducted with non-compliant patients to understand reasons for non-adherence.

RESULTS

Among 923 UIA diagnosed patients, 337 were randomly selected for analysis. The median follow-up period was 1.4 years, with a 42% first-year compliance rate. The mean aneurysm size was 3.3 mm. Five patients had a rupture during follow-up, of which 4 died. Compared with patients consulting specialists at the initial diagnosis, those seen by non-specialists exhibited lower compliance (OR 0.25, p < 0.001). Loss to follow-up was greatest during transition from emergency service to specialist appointments. Patients who spoke languages other than English exhibited poorer compliance than those speaking English (OR 0.20, p = 0.01).

CONCLUSIONS

Significant amounts of UIA patients at low rupture risk were lost to follow-up before seeing UIA specialists. Main non-compliance factors include inadequate comprehension of follow-up instructions, poor care transfer from non-specialists to specialist, and insurance barriers.

Gekko Coil System for Intracranial Aneurysms Treatment in China (GREAT-China): A Prospective Randomized Controlled Open-Label Noninferiority Trial

OBJECTIVE

This study aimed to evaluate the safety and efficacy of the Gekko coil system in treating intracranial aneurysms (IAs) in clinical practice.

METHODS

A prospective multicenter randomized open-label parallel positive control noninferiority trial was conducted by 11 centers in China. Patients with a target IA were randomized 1:1 to coiling with either Gekko or Axium coils. The primary outcome was successful aneurysm occlusion at 6 months postoperative follow-up, whereas the secondary outcomes included the successful occlusion aneurysm rate in the immediate postoperative period, recanalization rate at the 6 months follow-up, and technical success and security.

RESULTS

Between May 2018 and September 2020, 256 patients were enrolled and randomized. Per-protocol analysis showed that the successful aneurysm occlusion rate at 6 months was 96.08% for the Gekko coil group compared with 96.12% in the Axium coil group, with a difference of -0.04% (P = 0.877). The successful immediate aneurysm occlusion rates were 86.00% and 77.45% in the Gekko coil group and the Axium coil group, respectively, showing no significant difference between the 2 groups (P = 0.116), whereas the recanalization rates during the 6 months follow-up were 2.02% and 1.96% in the Gekko and Axium coil groups, respectively, which was not statistically significant (P = 1.000).

CONCLUSIONS

This trial showed that the Gekko coil system was noninferior to the Axium coil system in terms of efficacy and safety for IA embolization. In clinical practice, the Gekko coil system can be considered safe and effective for treating patients with IA.

ARISE I Consensus Review on the Management of Intracranial Aneurysms

BACKGROUND

Intracranial aneurysms (IAs) remain a challenging neurological diagnosis associated with significant morbidity and mortality. There is a plethora of microsurgical and endovascular techniques for the treatment of both ruptured and unruptured aneurysms. There is no definitive consensus as to the best treatment option for this cerebrovascular pathology. The Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts discussed best practices and the most promising approaches to improve the management of brain aneurysms.

METHODS

A group of experts from academia, industry, and federal regulators convened to discuss updated clinical trials, scientific research on preclinical system models, management options, screening and monitoring, and promising novel device technologies, aiming to improve the outcomes of patients with IA.

RESULTS

Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts suggested the incorporation of artificial intelligence to capture sequential aneurysm growth, identify predictors of rupture, and predict the risk of rupture to guide treatment options. The consensus strongly recommended nationwide systemic data collection of unruptured IA radiographic images for the analysis and development of machine learning algorithms for rupture risk. The consensus supported centers of excellence for preclinical multicenter trials in areas such as genetics, cellular composition, and radiogenomics. Optical coherence tomography and magnetic resonance imaging contrast-enhanced 3T vessel wall imaging are promising technologies; however, more data are needed to define their role in IA management. Ruptured aneurysms are best managed at large volume centers, which should include comprehensive patient management with expertise in microsurgery, endovascular surgery, neurology, and neurocritical care.

CONCLUSIONS

Clinical and preclinical studies and scientific research on IA should engage high-volume centers and be conducted in multicenter collaborative efforts. The future of IA diagnosis and monitoring could be enhanced by the incorporation of artificial intelligence and national radiographic and biologic registries. A collaborative effort between academic centers, government regulators, and the device industry is paramount for the adequate management of IA and the advancement of the field.

Towards the mechanical characterisation of unruptured intracranial aneurysms: Numerical modelling of interactions between a deformation device and the aneurysm wall

Intracranial aneurysm is a critical pathology related to the arterial wall deterioration. This work is an essential aspect of a large scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool regarding the rupture risk assessment. A machine learning algorithm links the aneurysm shape observed and a database of UIA clinical images associated with in vivo wall mechanical properties and rupture characterisation. The database constitution is derived from a device prototype coupled with medical imaging. It provides the mechanical characterisation of the aneurysm from the wall deformation obtained by inverse analysis based on the variation of luminal volume. Before performing in vivo tests of the device on small animals, a numerical model was built to quantify the device's impact on the aneurysm wall under natural blood flow conditions. As the clinician will never be able to precisely situate the device, several locations were considered. In preparation for the inverse analysis procedure, artery material laws of increasing complexity were studied (linear elastic, hyper elastic Fung-like). Considering all the device locations and material laws, the device induced relative displacements to the Systole peak (worst case scenario with the highest mechanical stimulus linked to the blood flow) ranging from 375 μm to 1.28 mm. The variation of luminal volume associated with the displacements was between 0.95 % and 4.3 % compared to the initial Systole volume of the aneurysm. Significant increase of the relative displacements and volume variations were found with the study of different cardiac cycle moments between the blood flow alone and the device application. For forthcoming animal model studies, Spectral Photon CT Counting, with a minimum spatial resolution of 250 μm, was selected as the clinical imaging technique. Based on this preliminary study, the displacements and associated volume variations (baseline for inverse analyse), should be observable and exploitable.

Nomogram-based geometric and hemodynamic parameters for predicting the growth of small untreated intracranial aneurysms

Previous studies have shown that the growth status of intracranial aneurysms (IAs) predisposes to rupture. This study aimed to construct a nomogram for predicting the growth of small IAs based on geometric and hemodynamic parameters. We retrospectively collected the baseline and follow-up angiographic images (CTA/ MRA) of 96 small untreated saccular IAs, created patient-specific vascular models and performed computational fluid dynamics (CFD) simulations. Geometric and hemodynamic parameters were calculated. A stepwise Cox proportional hazards regression analysis was employed to construct a nomogram. IAs were stratified into low-, intermediate-, and high-risk groups based on the total points from the nomogram. Receiver operating characteristic (ROC) analysis, calibration curves, decision curve analysis (DCA) and Kaplan-Meier curves were evaluated for internal validation. In total, 30 untreated saccular IAs were grown (31.3%; 95%CI 21.8%-40.7%). The PHASES, ELAPSS, and UIATS performed poorly in distinguishing growth status. Hypertension (hazard ratio [HR] 4.26, 95%CI 1.61-11.28; P = 0.004), nonsphericity index (95%CI 4.10-25.26; P = 0.003), max relative residence time (HR 1.01, 95%CI 1.00-1.01; P = 0.032) were independently related to the growth status. A nomogram was constructed with the above predictors and achieved a satisfactory prediction in the validation cohort. The log-rank test showed significant discrimination among the Kaplan-Meier curves of different risk groups in the training and validation cohorts. A nomogram consisting of geometric and hemodynamic parameters presented an accurate prediction for the growth status of small IAs and achieved risk stratification. It showed higher predictive efficacy than the assessment tools.

Addressing Challenges in Cerebral Aneurysm Management: Strategies to Enhance Patient Outcomes

We are pleased to present a Special Issue dedicated to addressing the current challenges in the management of cerebral aneurysms (CA) [...].

Microsurgical clipping of unruptured intracranial aneurysms by a single surgeon's experience: why should we preserve the neurosurgical skills in our health areas?

BACKGROUND

The long-standing comparison between the endovascular and microsurgical treatment is still ongoing. While not any center avails of a neuroendovascular service, and not every aneurysm is suitable for endovascular treatment, the neurovascular technique is slowly disappearing from our territories, whereas in the current literature, the role of the neurosurgical treatment is being re-appreciated. The aim of this paper was to discuss a single surgeon's clinical and radiological results with the microsurgical management of unruptured intracranial aneurysms (UIA).

METHODS

We retrospectively reviewed the clinical and radiological records of patients treated for UIA, by a single surgeon, in the period ranging between 2015 and 2019. We recorded all the relevant anatomic features of the aneurysm, saliencies of the surgical treatment, such as the need for temporary clipping, intraoperative rupture, or postoperative complications. The results of the clinical and radiological follow-up examinations were recorded either.

RESULTS

Fifty-eight patient undergoing microsurgical clipping were included, harboring a total of 65 UIAs. CTA with 3D reconstructions was sufficient to reach a reliable preoperative planning in 46 patients (76%). A total of 94% of the cases were unchanged or neurologically unremarkable at follow-up. The presence of postoperative complications was associated to the neck size and predictor of a longer hospitalizations, as well as longer hospitalizations are associated to the patients' age, size of the aneurysms and surgical times.

CONCLUSIONS

According to our experience, we believe that microsurgical clipping plays a critical role in the management of UIA, also on the ground of the encouraging results of the relevant literature.

In vivo mechanical characterization of arterial wall using an inverse analysis procedure: application on an animal model of intracranial aneurysm

Intracranial aneurysm is a pathology related to the deterioration of the arterial wall. This work is an essential part of a large-scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool to facilitate the rupture risk assessment. It will lean on the link between the aneurysm shape clinically observed and a database derived from the in vivo mechanical characterization of aneurysms. To supply this database, a deformation device prototype of the arterial wall was developed. Its use coupled with medical imaging (spectral photon-counting computed tomography providing a spatial resolution down to 250 μm) is used to determine the in vivo mechanical properties of the wall based on the inverse analysis of the quantification of the wall deformation observed experimentally. This study presents the in vivo application of this original procedure to an animal model of aneurysm. The mechanical properties of the aneurysm wall identified were consistent with the literature, and the errors between the numerical and experimental results were less than 10%. Based on these parameters, this study allows the assessment of the aneurysm stress state for a known solicitation and points towards the definition of a rupture criterion.

Evaluation of predictive models of aneurysm focal growth and bleb development using machine learning techniques

BACKGROUND

The presence of blebs increases the rupture risk of intracranial aneurysms (IAs).

OBJECTIVE

To evaluate whether cross-sectional bleb formation models can identify aneurysms with focalized enlargement in longitudinal series.

METHODS

Hemodynamic, geometric, and anatomical variables derived from computational fluid dynamics models of 2265 IAs from a cross-sectional dataset were used to train machine learning (ML) models for bleb development. ML algorithms, including logistic regression, random forest, bagging method, support vector machine, and K-nearest neighbors, were validated using an independent cross-sectional dataset of 266 IAs. The models' ability to identify aneurysms with focalized enlargement was evaluated using a separate longitudinal dataset of 174 IAs. Model performance was quantified by the area under the receiving operating characteristic curve (AUC), the sensitivity and specificity, positive predictive value, negative predictive value, F1 score, balanced accuracy, and misclassification error.

RESULTS

The final model, with three hemodynamic and four geometrical variables, along with aneurysm location and morphology, identified strong inflow jets, non-uniform wall shear stress with high peaks, larger sizes, and elongated shapes as indicators of a higher risk of focal growth over time. The logistic regression model demonstrated the best performance on the longitudinal series, achieving an AUC of 0.9, sensitivity of 85%, specificity of 75%, balanced accuracy of 80%, and a misclassification error of 21%.

CONCLUSIONS

Models trained with cross-sectional data can identify aneurysms prone to future focalized growth with good accuracy. These models could potentially be used as early indicators of future risk in clinical practice.

Sex differences in patients with and without high-risk factors associated with aneurysmal subarachnoid hemorrhage

BACKGROUND

Controversy remains regarding the appropriate screening for intracranial aneurysms or for the treatment of aneurysmal subarachnoid hemorrhage (aSAH) for patients without known high-risk factors for rupture. This study aimed to assess how sex affects both aSAH presentation and outcomes for aSAH treatment.

METHOD

A retrospective cohort study was conducted of all patients treated at a single institution for an aSAH during a 12-year period (August 1, 2007-July 31, 2019). An analysis of women with and without high-risk factors was performed, including a propensity adjustment for a poor neurologic outcome (modified Rankin Scale [mRS] score > 2) at follow-up.

RESULTS

Data from 1014 patients were analyzed (69% [n = 703] women). Women were significantly older than men (mean ± SD, 56.6 ± 14.1 years vs 53.4 ± 14.2 years, p < 0.001). A significantly lower percentage of women than men had a history of tobacco use (36.6% [n = 257] vs 46% [n = 143], p = 0.005). A significantly higher percentage of women than men had no high-risk factors for aSAH (10% [n = 70] vs 5% [n = 16], p = 0.01). The percentage of women with an mRS score > 2 at the last follow-up was significantly lower among those without high-risk factors (34%, 24/70) versus those with high-risk factors (53%, 334/633) (p = 0.004). Subsequent propensity-adjusted analysis (adjusted for age, Hunt and Hess grade, and Fisher grade) found no statistically significant difference in the odds of a poor outcome for women with or without high-risk factors for aSAH (OR = 0.7, 95% CI = 0.4-1.2, p = 0.18).

CONCLUSIONS

A higher percentage of women versus men with aSAH had no known high-risk factors for rupture, supporting more aggressive screening and management of women with unruptured aneurysms.

Optimal PHASES Scoring for Risk Stratification of Surgically Treated Unruptured Aneurysms

OBJECTIVE

The PHASES (Population, Hypertension, Age, Size, Earlier subarachnoid hemorrhage, Site) score was developed to facilitate risk stratification for management of unruptured intracranial aneurysms (UIAs). This study aimed to identify the optimal PHASES score cutoff for predicting neurologic outcomes in patients with surgically treated aneurysms.

METHODS

All patients who underwent microneurosurgical treatment for UIA at a large quaternary center from January 1, 2014, to December 31, 2020, were retrospectively reviewed. Inclusion criteria included a modified Rankin Scale (mRS) score of ≤2 at admission. The primary outcome was 1-year mRS score, with a "poor" neurologic outcome defined as an mRS score >2.

RESULTS

In total, 375 patients were included in the analysis. The mean (SD) PHASES score for the entire study population was 4.47 (2.67). Of 375 patients, 116 (31%) had a PHASES score ≥6, which was found to maximize prediction of poor neurologic outcome. Patients with PHASES scores ≥6 had significantly higher rates of poor neurologic outcome than patients with PHASES scores <6 at discharge (58 [50%] vs. 90 [35%], P = 0.005) and follow-up (20 [17%] vs. 18 [6.9%], P = 0.002). After adjusting for age, Charlson Comorbidity Index score, nonsaccular aneurysm, and aneurysm size, PHASES score ≥6 remained a significant predictor of poor neurologic outcome at follow-up (odds ratio, 2.75; 95% confidence interval, 1.42-5.36, P = 0.003).

CONCLUSIONS

In this retrospective analysis, a PHASES score ≥6 was associated with significantly greater proportions of poor outcome, suggesting that awareness of this threshold in PHASES scoring could be useful in risk stratification and UIA management.

Pipeline Embolization Device for intracranial aneurysms presenting with mass effect: a large Chinese cohort

BACKGROUND

Unruptured intracranial aneurysm treatment aims to reduce the risk of aneurysm rupture and bleeding, relieves symptoms and improve the quality of life for patients. This study aimed to assess the safety and efficacy of Pipeline Embolization Device (PED, Covidien/Medtronic, Irvine, CA) treatment for intracranial aneurysms presenting with mass effect in real-world settings.

METHODS

We selected patients from the PED in China Post-Market Multi-Center Registry Study with mass effect presentation. The study endpoints included postoperative mass effect deterioration and mass effect relief at follow-up (3-36 months). We conducted multivariate analysis to identify factors associated with mass effect relief. Subgroup analyses by aneurysm location, size and form were also performed.

RESULTS

This study included 218 patients with a mean age of 54.3±11.8 years and a female predominance of 74.0% (162/218). The postoperative mass effect deterioration rate was 9.6% (21/218). During a median follow-up period of 8.4 months, the mass effect relief rate was 71.6% (156/218). Notably, immediate aneurysm occlusion following treatment was significantly associated with mass effect relief (OR 0.392, 95% CI, 0.170 to 0.907, p=0.029). Subgroup analysis demonstrated that adjunctive coiling contributed to mass effect relief in cavernous aneurysms, while dense embolism impeded symptom relief in aneurysms<10 mm and saccular aneurysms.

CONCLUSIONS

Our data confirmed the efficacy of PED in relieving mass effect. The findings of this study provide support for endovascular treatment to alleviate mass effect in unruptured intracranial aneurysms.

TRIAL REGISTRATION NUMBER

NCT03831672.

Navigating Complexity: A Comprehensive Approach to Middle Cerebral Artery Aneurysms

Background: The concept of aneurysm "complexity" has undergone significant changes in recent years, with advancements in endovascular treatments. However, surgical clipping remains a relevant option for middle cerebral artery (MCA) aneurysms. Hence, the classical criteria used to define surgically complex MCA aneurysms require updating. Our objective is to review our institutional series, considering the impacts of various complexity features, and provide a treatment strategy algorithm. Methods: We conducted a retrospective review of our institutional experience with "complex MCA" aneurysms and analyzed single aneurysmal-related factors influencing treatment decisions. Results: We identified 14 complex cases, each exhibiting at least two complexity criteria, including fusiform shape (57%), large size (35%), giant size (21%), vessel branching from the sac (50%), intrasaccular thrombi (35%), and previous clipping/coiling (14%). In 92% of cases, the aneurysm had a wide neck, and 28% exhibited tortuosity or stenosis of proximal vessels. Conclusions: The optimal management of complex MCA aneurysms depends on a decision-making algorithm that considers various complexity criteria. In a modern medical setting, this process helps clarify the choice of treatment strategy, which should be tailored to factors such as aneurysm morphology and patient characteristics, including a combination of endovascular and surgical techniques.

Glypican-1 may be a plasma biomarker for predicting the rupture of small intracranial aneurysms

Currently, there are no effective methods for predicting the rupture of asymptomatic small intracranial aneurysms (IA) (<7 mm). In this study the aim was to identify early warning biomarkers in peripheral plasma for predicting IA rupture. Four experimental groups were included: ruptured intracranial aneurysm (RIA), unruptured intracranial aneurysm (UIA), traumatic subarachnoid hemorrhage control (tSAHC), and healthy control (HC) groups. Plasma proteomics of these four groups were detected using iTRAQ combined LC-MS/MS. Differentially expressed proteins (DEPs) were identified in RIA, UIA, tSAHC compared with HC. Target proteins associated with aneurysm rupture were obtained by comparing the DEPs of the RIA and UIA groups after filtering out the DEPs of the tSAHC group. The plasma concentrations of target proteins were validated using enzyme-linked immunosorbent assay (ELISA). The iTRAQ analysis showed a significant increase in plasma GPC1 concentration in the RIA group compared to the UIA group, which was further validated among the IA patients. Logistic regression analysis identified GPC1 as an independent risk factor for predicting aneurysm rupture. The ROC curve indicated that the GPC1 plasma cut-off value for predicting aneurysms rupture was 4.99 ng/ml. GPC1 may be an early warning biomarker for predicting the rupture of small intracranial aneurysms. SIGNIFICANCE: The current management approach for asymptomatic small intracranial aneurysms (<7 mm) is limited to conservative observation and surgical intervention. However, the decision-making process regarding these options poses a dilemma due to weighing their respective advantages and disadvantages. Currently, there is a lack of effective diagnostic methods to predict the rupture of small aneurysms. Therefore, our aim is to identify early warning biomarkers in peripheral plasma that can serve as quantitative detection markers for predicting intracranial aneurysm rupture. In this study, four experimental populations were established: small ruptured intracranial aneurysm (sRIA) group, small unruptured intracranial aneurysm (sUIA) group, traumatic subarachnoid hemorrhage control (tSAHC) group, and healthy control (HC) group. The tSAH group was the control group of spontaneous subarachnoid hemorrhage caused by ruptured aneurysm. Compared with patients with UIA, aneurysm tissue and plasma GPC1 in patients with RIA is significantly higher, and GPC1 may be an early warning biomarker for predicting the rupture of intracranial small aneurysms.

Predictors for Rupture of Small (<7mm) Intracranial Aneurysms: A Systematic Review and Meta-Analysis

INTRODUCTION

Identifying predictors for rupture of small intracranial aneurysms (sIAs) have become a growing topic in the literature given the relative paucity of data on their natural history. The authors performed a meta-analysis to identify reliable predictors.

METHODS

PubMed, Scopus, and Web of Science were used to systematically extract references which involved at least 10 IAs <7mm which including a control group experiencing no rupture. All potential predictors reported in the literature were evaluated in the meta-analysis.

RESULTS

Fifteen studies yielding 4,739 sIAs were included in the meta-analysis. Four studies were prospective and 11 were retrospective. Univariate analysis identified 7 predictors which contradicted or are absent in the current scoring systems, while allowing to perform subgroup analysis for further reliability: patient age (MD -1.97, 95%CI -3.47-0.48; P = 0.01), the size ratio (MD 0.40, 95%CI 0.26-0.53; P < 0.00001), the aspect ratio (MD 0.16, 95%CI 0.11-0.22; P < 0.00001), bifurcation point (OR 3.76, 95%CI 2.41-5.85; P < 0.00001), irregularity (OR 2.95, 95%CI 1.91-4.55; P < 0.00001), the pressure loss coefficient (MD -0.32, 95%CI -0.52-0.11; P = 0.002), wall sheer stress (Pa) (MD -0.16, 95%CI -0.28-0.03; P = 0.01). All morphology related predictors listed above have been confirmed as independent predictors via multivariable analysis among the individual studies.

CONCLUSIONS

Morphology related predictors are superior to the classic patient demographic predictors present in most scoring systems. Given that morphology predictors take time to measure, our findings may be of great interest to developers seeking to incorporate artificial intelligence into the treatment decision-making process.

Retrospective Application of Risk Scores to Unruptured Anterior Communicating Artery Aneurysms

BACKGROUND

Treatment decisions for unruptured intracranial aneurysms (UIAs) pose a challenge for neurosurgeons, prompting the development of clinical scales assessing hemorrhage risk to provide management guidance. This study compares recommendations from the PHASES and UIA treatment scores (UIATS) applied to anterior communicating artery (AComA) UIAs against real-world management.

METHODS

While UIATS recommends management, for PHASES, an aneurysm with score of 10 or more was considered "high-risk". Analysis involved assessing the concordance in each group alongside comparison to real-word management.

RESULTS

Among 129 patients, 46.5% were observed and 53.5% were treated. PHASES scores were significantly higher in the treatment group (p = 0.00002), and UIATS recommendations correlated with real-world decisions (p < 0.001). We observed no difference in the frequencies of UIATS recommendations between high- and low-risk groups. When comparing the UIATS and PHASES, 33% of high-risk aneurysms received a UIATS conservative management recommendation. In 39% of high-risk aneurysms, the UIATS recommendation was not definitive. Conversely, 27% of low-risk aneurysms obtained a UIATS UIA repair recommendation. Overall, concordance between PHASES and UIATS was 32%.

CONCLUSIONS

Significant discordance in therapeutic suggestions underscores the predominant influence of center experience and individual assessments. Future studies should refine and validate decision-making strategies, potentially exploring alternative applications or developing tailored scales.

Risk factors of unruptured intracranial aneurysms instability in the elderly

BACKGROUND

Presently, a consistent strategy for determining the stability of unruptured intracranial aneurysms (UIAs) in elderly patients is lacking, primarily due to the unique characteristics of this demographic. Our objective was to assess the risk factors contributing to aneurysm instability (growth or rupture) within the elderly population.

METHODS

In this study, we compiled data from follow-up patients with UIAs spanning from November 2016 to August 2021. We specifically focused on patients aged ≥ 60 years. Clinical histories were gathered, and morphological parameters of aneurysms were measured. The growth of aneurysms was determined using the computer-assisted semi-automated measurement (CASAM). Growth and rupture rates of UIAs were calculated, and both univariate and multivariate Cox regression analyses were conducted. Additionally, Kaplan-Meier survival curves were plotted.

RESULTS

A total of 184 patients with 210 aneurysms were enrolled in the study. The follow-up period encompasses 506.6 aneurysm-years and 401.4 patient-years. Among all the aneurysms, 23 aneurysms exhibited growth, with an annual aneurysm growth rate of 11.0%, and 1 (4.5%) experienced rupture, resulting in an annual aneurysm rupture rate of 0.21%. Multivariate Cox analysis identified poorly controlled hypertension (P = 0.011) and high-risk aneurysms (including anterior cerebral artery (ACA), anterior communicating artery (AcoA), posterior communicating artery aneurysm (PcoA), posterior circulation (PC) > 4 mm or distal internal carotid artery (ICAd), middle cerebral artery (MCA), and PC > 7 mm) (P = 0.006) as independent risk factors for the development of unstable aneurysms.

CONCLUSIONS

In the elderly, poorly controlled hypertension and high-risk aneurysms emerge as significant risk factors for aneurysm instability. This underscores the importance of rigorous surveillance or timely intervention in patients presenting with these risk factors.

Microsurgical Clipping of Unruptured Anterior Circulation Aneurysms-A Global Multicenter Investigation of Perioperative Outcomes

BACKGROUND AND OBJECTIVES

Microsurgical aneurysm repair by clipping continues to be highly important despite increasing endovascular treatment options, especially because of inferior occlusion rates. This study aimed to present current global microsurgical treatment practices and to identify risk factors for complications and neurological deterioration after clipping of unruptured anterior circulation aneurysms.

METHODS

Fifteen centers from 4 continents participated in this retrospective cohort study. Consecutive patients who underwent elective microsurgical clipping of untreated unruptured intracranial aneurysm between January 2016 and December 2020 were included. Posterior circulation aneurysms were excluded. Outcome parameters were postsurgical complications and neurological deterioration (defined as decline on the modified Rankin Scale) at discharge and during follow-up. Multivariate regression analyses were performed adjusting for all described patient characteristics.

RESULTS

Among a total of 2192 patients with anterior circulation aneurysm, complete occlusion of the treated aneurysm was achieved in 2089 (95.3%) patients at discharge. The occlusion rate remained stable (94.7%) during follow-up. Regression analysis identified hypertension (P < .02), aneurysm diameter (P < .001), neck diameter (P < .05), calcification (P < .01), and morphology (P = .002) as preexisting risk factors for postsurgical complications and neurological deterioration at discharge. Furthermore, intraoperative aneurysm rupture (odds ratio 2.863 [CI 1.606-5.104]; P < .01) and simultaneous clipping of more than 1 aneurysm (odds ratio 1.738 [CI 1.186-2.545]; P < .01) were shown to be associated with an increased risk of postsurgical complications. Yet, none of the surgical-related parameters had an impact on neurological deterioration. Analyzing volume-outcome relationship revealed comparable complication rates (P = .61) among all 15 participating centers.

CONCLUSION

Our international, multicenter analysis presents current microsurgical treatment practices in patients with anterior circulation aneurysms and identifies preexisting and surgery-related risk factors for postoperative complications and neurological deterioration. These findings may assist in decision-making for the optimal therapeutic regimen of unruptured anterior circulation aneurysms.