Natural history of unruptured intracranial aneurysms: probability of and risk factors for aneurysm rupture

Exosomes in Vascular/Neurological Disorders and the Road Ahead

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), stroke, and aneurysms, are characterized by the abnormal accumulation and aggregation of disease-causing proteins in the brain and spinal cord. Recent research suggests that proteins linked to these conditions can be secreted and transferred among cells using exosomes. The transmission of abnormal protein buildup and the gradual degeneration in the brains of impacted individuals might be supported by these exosomes. Furthermore, it has been reported that neuroprotective functions can also be attributed to exosomes in neurodegenerative diseases. The potential neuroprotective functions may play a role in preventing the formation of aggregates and abnormal accumulation of proteins associated with the disease. The present review summarizes the roles of exosomes in neurodegenerative diseases as well as elucidating their therapeutic potential in AD, PD, ALS, HD, stroke, and aneurysms. By elucidating these two aspects of exosomes, valuable insights into potential therapeutic targets for treating neurodegenerative diseases may be provided.

Treatment of giant intracranial aneurysms using the Pipeline flow-diverting stent: Long-term results from the International Retrospective Study of the Pipeline Embolization Device (IntrePED) study

BACKGROUND

Traditional endovascular treatments of giant intracranial aneurysms are associated with high rates of complications and retreatment. Our objective was to examine the safety and long-term efficacy of the Pipeline Embolization Device for treatment of these aneurysms.

METHODS

This retrospective study using the IntrePED database included all patients with giant intracranial aneurysms treated with the Pipeline device between July 2008 and February 2013. Efficacy outcomes were stratified by using the Raymond-Roy Occlusion Classification. Predefined safety outcomes included spontaneous rupture of the target aneurysm; ipsilateral intracranial hemorrhage; ischemic stroke; parent artery stenosis; and sustained cranial neuropathy.

RESULTS

Sixty-six embolizations were performed to treat 63 giant intracranial aneurysms (including 2 ruptured): 49 (77.8%) in the anterior and 14 (22.2%) in the posterior circulation. The median follow-up was 22.4 (0.1-60.5) months. Class I angiographic occlusion was achieved in 72.0% (36/50). The neurological morbidity/mortality rate was 23.8% (15/63), with higher rates in the posterior circulation than in the anterior circulation (22.4% vs. 28.6%). Among seven deaths, five had neurological causes. The procedure-related neurological morbidity and mortality rates were 22.7% (15/66) and 7.6% (5/66), respectively. The spontaneous rupture rate was 4.5% (3/66). Two spontaneous ruptures (1 death), 4/4 postprocedural intracranial hemorrhages, and 6/9 ischemic events occurred within 30 days. In-stent stenosis and new-onset cranial neuropathy were not observed during the angiographic follow-up period.

CONCLUSIONS

Although procedure-related neurological morbidity/mortality rates were not insignificant, this study confirms the feasibility and long-term efficacy of the Pipeline Embolization Device to treat giant intracranial aneurysms.

Risk Factors and Location of Intracranial Aneurysm Rupture in a Consecutive Chinese Han Population

OBJECTIVE

The aim of the present study was to retrospectively analyze and investigate the clinical data of 704 cases of ruptured intracranial aneurysms (RIAs) and unruptured intracranial aneurysms (UIAs). The risk factors predicting aneurysm rupture were explored from the perspective of the clinical characteristics of intracranial aneurysm (IA).

METHODS

The clinical data of 704 patients with RIAs (494 patients) and UIAs (210 patients) admitted to the Department of Neurosurgery of Tianjin Medical University General Hospital and Tianjin Fifth Central Hospital between January 2016 and May 2022 were analyzed. A detailed analysis of sex, age, history, personal history, drug intake, and site of aneurysm occurrence was performed. Age was analyzed in segments and strata, and parameters with significant differences in the preliminary analysis results were analyzed by logistic regression to predict factors associated with the risk of aneurysm rupture.

RESULTS

Among 494 patients with RIA (70.2%) and 210 patients with UIA (29.8%), the logistic regression showed that IA location appeared to be the most significant factor associated with RIA (OR, 95% CI: internal carotid artery (ICA), reference; anterior communicating artery,27.864,12.548-61.878; posterior communicating artery,12.408,6.658-23.124; anterior cerebral artery,5.804,2.333-14.440; middle cerebral artery,9.284,4.599-18.744; posterior circulation arteries, 4.224,2.011-8.871). Age was not a significant factor associated with RIA in the model and Hyperlipidemia (OR: 0.365; 95% CI: 0.171-0.779), Atherosclerosis (OR: 0.277; 95% CI: 0.172-0.446) and Multiple aneurysms (OR: 0.275; 95% CI: 0.177-0.425) patients were less likely to have RIA.IA location and age were the best predictors of RIA using the model.

CONCLUSIONS

The present findings indicated that hyperlipidemia and atherosclerosis have a protective effect on aneurysm rupture, and different anatomical sites of IA may be risk factors for the occurrence of IA rupture. Among the anatomical sites of IA, the anterior communicating artery and posterior communicating artery have a higher fracture risk.

Giant Aneurysms: Not So Giant in Behavior

BACKGROUND

Giant intracranial aneurysms (GIAs) are very complex in their behavior and treatment procedure. There are various modalities of treatment. The annual rupture rate of GIA (6%) is higher than that of small aneurysms (1-3%). Neurosurgeons handle these aneurysms during operations.

OBJECTIVE

We tried to analyze the intraoperative rupture rate (IRR) of GIA in relation to small aneurysms. IRR is concerned with the rupture of the aneurysms during operative handling.

MATERIALS AND METHODS

For conducting the study, we compared the IRR of 7 GIAs and 45 small aneurysms during a span of 10 years. All the operations were performed by the same team and the same principal surgeon. IRR was compared by statistical analysis.

RESULT

Z-test was done to compare the two rates: Z = 0.68 and P = 0.49. According to our study, the IRR of GIA is not statistically different from small aneurysms. The IRR of GIA is not higher because of three factors which we have analyzed: 1) layers of intraaneurysmal thrombus, 2) fibrin deposition on the aneurysm wall, and 3) blocked neck of the aneurysm by thrombus.

CONCLUSION

The IRR of GIA is not different from small aneurysms.

Prognostic Risk Factors of One-stage Surgical Clipping in aSAH Elderly Patients with MIAs

OBJECTIVE

To discuss the prognostic factors affecting the prognosis of 1-stage surgical clipping in aneurysmal subarachnoid hemorrhage (aSAH) elderly patients with multiple intracranial aneurysms (MIAs).

MATERIALS AND METHODS

A total of 84 elderly patients with aSAH who had MIAs and underwent 1-stage surgical clipping were retrospectively analyzed. Follow-up was conducted with patients 30 days after discharge using the Glasgow Outcome Scale (GOS). A GOS score of 1 to 3 was defined as a poor outcome, and a GOS score of 4 to 5 was defined as a good outcome. General information (gender, age, size of aneurysm, location of rupture of the responsible aneurysm, H-H grade, CT characteristics of aSAH, number of subarachnoid hemorrhages, operation opportunity, postoperative complications, and intraoperative rupture) and complications（cerebral infarction, hydrocephalus, electrolyte disturbance, and encephaledema）were recorded. Univariate analysis and multivariate regression analysis were used to analyze factors that may affect outcomes.

RESULTS

Univariate analysis showed that the number of SAH events ( P =0.005), intraoperative rupture ( P =0.048) and postoperative complications ( P =0.002) were associated with the prognosis of aSAH elderly patients with MIAs undergoing 1-stage surgery. Multivariate analysis showed that the number of SAH events (odds ratio [OR] 4.740, 95% confidence interval [CI] 1.056 to 21.282, P =0.042) and postoperative complications (OR 4.531, 95% CI 1.266 to 16.220, P =0.020) were independently associated with the prognosis of aSAH elderly patients with MIAs undergoing 1-stage surgery.

CONCLUSIONS

The number of SAH events and postoperative complications are independent risk factors for the prognosis of aSAH elderly patients with MIAs undergoing 1-stage surgery. These factors contribute to the timely treatment of potentially related patients.

FSTIF-UNet: A Deep Learning-Based Method Towards Automatic Segmentation of Intracranial Aneurysms in Un-Reconstructed 3D-RA

Segmentation of intracranial aneurysms (IAs) is an important step for the diagnosis and treatment of IAs. However, the process by which clinicians manually recognize and localize IAs is overly labor intensive. This study aims to develop a deep-learning-based framework (defined as FSTIF-UNet) towards IAs segmentation in un-reconstructed 3D Rotational Angiography (3D-RA) images. 3D-RA sequences from 300 patients with IAs from Beijing Tiantan Hospital are enrolled. Inspired by radiologists' clincial skills, a Skip-Review attention mechanism is proposed to repeatedly fuse the long-term spatiotemporal features of several images with the most obvious IA's features (sellected by a pre-detection network). Then, a Conv-LSTM is used to fuse the short-term spatiotemporal features of the selected 15 3D-RA images from the equally-spaced viewing angles. The combination of the two modules realizes the full-scale spatiotemporal information fusion of the 3D-RA sequence. FSTIF-UNet achieves DSC, IoU, Sens, Haus, and F1-Score of 0.9109, 0.8586, 0.9314, 1.358 and 0.8883, respectively, and time taken for network segmentation is 0.89 s/case. The results show significant improvement in IA segmentation performance with FSTIF-UNet compared with baseline networks (with DSC from 0.8486 - 0.8794). The proposed FSTIF-UNet establishes a practical method to assist the radiologists in clinical diagnosis.

Pulmonary Edema After Intracranial Aneurysm Clipping in Kyphosis: A Case Report

Introduction

A 56-year-old female patient was admitted to the hospital for "10+days of right eye droop and 1 day of aggravation". After admission, the physical examination found that the patient had severe scoliosis. 3D reconstruction and enhanced CT scan of the head vessels showed that the right internal carotid artery C6 aneurysms were clipped under general anesthesia. After the operation, the patient had increased airway pressure, with a large number of pink foam sputum attracted from the trachea catheter, and the lungs were scattered with moist rales during auscultation, After the treatment of anti-heart failure, the patient returned to the ICU through the trachea catheter. Eight hours later, the trachea catheter was pulled out and the patient was released from the ventilator. The symptoms were relieved on the fifth day after the operation. This case report describes the perioperative management of intracranial aneurysm with severe scoliosis. After strict monitoring and timely treatment during the perioperative period, the patient turned from crisis to safety, providing some reference for colleagues who encounter such patients in the future.

Conclusion

In patients with scoliosis, due to long-term compression of the thorax, pulmonary restrictive ventilation dysfunction, small airway function and diffusion function are reduced, and cardiac function is decreased. Therefore, during the operation of intracranial aneurysms, fluid infusion should be careful, and volume monitoring should be done at all times to maintain the effective circulating blood volume of the body and prevent the aggravation of cardiac insufficiency and pulmonary edema.

Risk factors for the rupture of anterior communicating artery aneurysms: Coexistence of fetal-type posterior cerebral artery and A1 segment hypoplasia/agenesis

PURPOSE

To investigate the effect of the coexistence of fetal-type posterior communicating artery (fPCA) and anterior cerebral artery (ACA) A1 segment agenesis/hypoplasia on the rupture of an anterior communicating artery (AComA) aneurysm.

MATERIALS AND METHODS

A total of 216 patients consecutively presenting with AComA aneurysms between January 2014 and December 2021 on digital subtraction angiography were evaluated. Patients without three-dimensional rotational angiography images, those aged under 18 years, those with suspected mycotic aneurysms, and those with dissecting and giant aneurysms were excluded from the study. The aneurysms were divided into two groups as ruptured and non-ruptured. Hemodynamic filling patterns were classified into four different types.

RESULTS

The study included 192 AComA aneurysms, 44.8% (n = 86) ruptured and 55.2% (n = 106) non-ruptured. According to hemodynamic filling patterns, in type 1, the frequency of non-ruptured aneurysms was statistically significantly higher than that of ruptured aneurysms (39.5% vs 18.9%; p = 0.001). In type 4, where fPCA and ACA A1 segment agenesis/hypoplasia coexists, the frequency of ruptured aneurysms was significantly higher than that of non-ruptured aneurysms (10.5% vs 22.7%; p = 0.026). The most common aneurysm size range was 4-7 mm (n = 85; 44.3%). There was no statistically significant difference in size between the ruptured and non-ruptured aneurysms (p = 0.627).

CONCLUSION

According to the hemodynamic filling classification, we observed that the presence of type 4 filling pattern, i.e., the coexistence of ACA A1 segment agenesis/hypoplasia and fPCA, increased the risk of rupture in AComA aneurysms.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Optimal Cost-Effective Screening Strategy for Unruptured Intracranial Aneurysms in Female Smokers

BACKGROUND

The prevalence of intracranial aneurysms among female cigarette smokers was shown to be high in previous studies, yet the cost-effectiveness of screening them has never been explored.

OBJECTIVE

To explore the most cost-effective screening strategy for female smokers.

METHODS

A decision analytical study was performed with a Markov model to compare different screening strategies with no screening and to explore the most optimal screening strategy for female smokers. Input data for the model were extracted from literature. A single screening at different ages and multiple screening every 15 years, 10 years, 5 years, and 2 years were performed for female smokers in different age ranges. Deterministic and probabilistic sensitivity analyses were performed to evaluate the robustness of the model. Finally, value of information analysis was performed to investigate the value of collecting additional data.

RESULTS

Screening female smokers for unruptured intracranial aneurysm is cost-effective. All screening strategies yield extra quality-adjusted life years. Screening at younger age brings more health benefit at lower cost. Frequent screening strategies decrease rupture rate of aneurysms more with higher costs per quality-adjusted life year. Screening after age 70 years and frequent screening (every 2 years) after age 60 years is not optimal. Among all the parameters in the model, collecting additional data on utility of the unscreened population would be most valuable.

CONCLUSION

Screening female smokers for intracranial aneurysms once at younger age is most optimal. However, in clinical practice, the duration and intensity of exposure to cigarettes should be taken into consideration.

Artificial intelligence aneurysm measurement tool finds growth in all aneurysms that ruptured during conservative management

BACKGROUND

Cerebral aneurysm rupture is associated with high rates of morbidity and mortality. Detecting aneurysms at high risk of rupture is critical in management decision making. Rupture risk has traditionally been associated with size-measured as a maximum dimension. However, aneurysms are morphologically dynamic, a characteristic ignored by large prospective aneurysm risk studies. Manual measurement is challenging and fraught with error. We used an artificial intelligence (AI) measurement tool to study aneurysms that ruptured during conservative management to detect changes in size not appreciated by manual linear measurement.

METHODS

A single practice database with >5000 aneurysms was queried. Patients followed conservatively for an unruptured aneurysm were identified using appropriate diagnosis codes. This cohort was screened for subsequent rupture using procedure codes. Only patients with two vascular imaging studies before rupture were included.

RESULTS

Five patients met the criteria. All patients had aneurysm enlargement, two of which were not detected from manual linear measurements, including adjudication and analysis, during a multidisciplinary neurovascular conference in a high volume practice. Maximum dimension increased at a minimum of 1.8% (range 1.8-63.3%) from the first scan to the last, and aneurysm volume increased at a minimum of 5.9% (5.9-385.5%), highlighting the importance of volumetric measurement.

CONCLUSIONS

AI-enabled volumetric measurements are more sensitive to changes in size and detected enlargement in all aneurysms that ruptured during conservative management. This finding has major implications for clinical practice and methods used for interval aneurysm measurement in patients being conservatively followed.

European Stroke Organisation (ESO) guidelines on management of unruptured intracranial aneurysms

Unruptured intracranial aneurysms (UIA) occur in around 3% of the population. Important management questions concern if and how to perform preventive UIA occlusion; if, how and when to perform follow up imaging and non-interventional means to reduce the risk of rupture. Using the Standard Operational Procedure of ESO we prepared guidelines according to GRADE methodology. Since no completed randomised trials exist, we used interim analyses of trials, and meta-analyses of observational and case-control studies to provide recommendations to guide UIA management. All recommendations were based on very low evidence. We suggest preventive occlusion if the estimated 5-year rupture risk exceeds the risk of preventive treatment. In general, we cannot recommend endovascular over microsurgical treatment, but suggest flow diverting stents as option only when there are no other low-risk options for UIA repair. To detect UIA recurrence we suggest radiological follow up after occlusion. In patients who are initially observed, we suggest radiological monitoring to detect future UIA growth, smoking cessation, treatment of hypertension, but not treatment with statins or acetylsalicylic acid with the indication to reduce the risk of aneurysm rupture. Additionally, we formulated 15 expert-consensus statements. All experts suggest to assess UIA patients within a multidisciplinary setting (neurosurgery, neuroradiology and neurology) at centres consulting >100 UIA patients per year, to use a shared decision-making process based on the team recommendation and patient preferences, and to repair UIA only in centres performing the proposed treatment in >30 patients with (ruptured or unruptured) aneurysms per year per neurosurgeon or neurointerventionalist. These UIA guidelines provide contemporary recommendations and consensus statement on important aspects of UIA management until more robust data come available.

Diagnostic Errors in Cerebrovascular Pathology: Retrospective Analysis of a Neuroradiology Database at a Large Tertiary Academic Medical Center

BACKGROUND AND PURPOSE

Diagnostic errors affect 2%-8% of neuroradiology studies, resulting in significant potential morbidity and mortality. This retrospective analysis of a large database at a single tertiary academic institution focuses on diagnostic misses in cerebrovascular pathology and suggests error-reduction strategies.

MATERIALS AND METHODS

CT and MR imaging reports from a consecutive database spanning 2015-2020 were searched for errors of attending physicians in cerebrovascular pathology. Data were collected on missed findings, study types, and interpretation settings. Errors were categorized as ischemic, arterial, venous, hemorrhagic, and "other."

RESULTS

A total of 245,762 CT and MR imaging neuroradiology examinations were interpreted during the study period. Vascular diagnostic errors were present in 165 reports, with a mean of 49.6 (SD, 23.3) studies on the shifts when an error was made, compared with 34.9 (SD, 19.2) on shifts without detected errors (P < .0001). Seventy percent of examinations occurred in the hospital setting; 93.3% of errors were perceptual; 6.7% were interpretive; and 93.9% (n = 155) were clinically significant (RADPEER 2B or 3B). The distribution of errors was arterial and ischemic each with 33.3%, hemorrhagic with 21.8%, and venous with 7.5%. Most errors involved brain MR imaging (30.3%) followed by head CTA (27.9%) and noncontrast head CT (26.1%). The most common misses were acute/subacute infarcts (25.1%), followed by aneurysms (13.7%) and subdural hematomas (9.7%).

CONCLUSIONS

Most cerebrovascular diagnostic errors were perceptual and clinically significant, occurred in the emergency/inpatient setting, and were associated with higher-volume shifts. Diagnostic errors could be minimized by adjusting search patterns to ensure vigilance on the sites of the frequently missed pathologies.

Unruptured cerebral aneurysm risk stratification: Background, current research, and future directions in aneurysm assessment

Background:

The optimal management of unruptured cerebral aneurysms is widely debated in the medical field. Rapid technology advances, evolving understanding of underlying pathophysiology, and shifting practice patterns have made the cerebrovascular field particularly dynamic in recent years. Despite progress, there remains a dearth of large randomized studies to help guide the management of these controversial patients.

Methods:

We review the existing literature on the natural history of unruptured cerebral aneurysms and highlight ongoing research aimed at improving our ability to stratify risk in these patients.

Results:

Landmark natural history studies demonstrated the significance of size, location, and other risk factors for aneurysm rupture, but prior studies have significant limitations. We have begun to understand the underlying pathophysiology behind aneurysm formation and rupture and are now applying new tools such as flow dynamics simulations and machine learning to individualize rupture risk stratification.

Conclusion:

Prior studies have identified several key risk factors for aneurysmal rupture, but have limitations. New technology and research methods have enabled us to better understanding individual rupture risk for patients with unruptured cerebral aneurysms.

Sex Difference and Rupture Rate of Intracranial Aneurysms: An Individual Patient Data Meta-Analysis

Supplemental Digital Content is available in the text.

Background and Purpose:

In previous studies, women had a higher risk of rupture of intracranial aneurysms than men, but female sex was not an independent risk factor. This may be explained by a higher prevalence of patient- or aneurysm-related risk factors for rupture in women than in men or by insufficient power of previous studies. We assessed sex differences in rupture rate taking into account other patient- and aneurysm-related risk factors for aneurysmal rupture.

Methods:

We searched Embase and Pubmed for articles published until December 1, 2020. Cohorts with available individual patient data were included in our meta-analysis. We compared rupture rates of women versus men using a Cox proportional hazard regression model adjusted for the PHASES score (Population, Hypertension, Age, Size of Aneurysm, Earlier Subarachnoid Hemorrhage From Another Aneurysm, Site of Aneurysm), smoking, and a positive family history of aneurysmal subarachnoid hemorrhage.

Results:

We pooled individual patient data from 9 cohorts totaling 9940 patients (6555 women, 66%) with 12 193 unruptured intracranial aneurysms, and 24 357 person-years follow-up. Rupture occurred in 163 women (rupture rate 1.04%/person-years [95% CI, 0.89–1.21]) and 63 men (rupture rate 0.74%/person-years [95% CI, 0.58–0.94]). Women were older (61.9 versus 59.5 years), were less often smokers (20% versus 44%), more often had internal carotid artery aneurysms (24% versus 17%), and larger sized aneurysms (≥7 mm, 24% versus 23%) than men. The unadjusted women-to-men hazard ratio was 1.43 (95% CI, 1.07–1.93) and the adjusted women/men ratio was 1.39 (95% CI, 1.02–1.90).

Conclusions:

Women have a higher risk of aneurysmal rupture than men and this sex difference is not explained by differences in patient- and aneurysm-related risk factors for aneurysmal rupture. Future studies should focus on the factors explaining the higher risk of aneurysmal rupture in women.

Imaging versus Intervention in Managing Small Unruptured Intracranial Aneurysms: A Cost-Effectiveness Analysis

OBJECTIVE

Current guidelines recommend active surveillance with serial magnetic resonance angiography (MRA) for management of small, asymptomatic unruptured anterior circulation aneurysms (UIAs). We sought to determine the cost-effectiveness of active surveillance compared to immediate surgery.

METHODS

We developed a Markov cost-effectiveness model simulating patients with small (<7 mm) UIAs managed by active surveillance via MRA, immediate surgery, or watchful waiting. Inputs for the model were abstracted from the literature and used to construct a comprehensive model following persons from diagnosis to death. Outcomes were quality-adjusted life-years (QALYs), lifetime medical costs (2015 USD), and incremental cost-effectiveness ratios (ICERs). Cost-effectiveness, deterministic, and probabilistic sensitivity analyses were performed.

RESULTS

Immediate surgical treatment was the most cost-effective management strategy for small UIAs with ICER of USD 45,772 relative to active surveillance. Sensitivity analysis demonstrated immediate surgery was the preferred strategy, if rupture rate was >0.1%/year and if the diagnosis age was <70 years, while active surveillance was preferred if surgical complication risk was >11%. Probabilistic sensitivity analysis demonstrated that at a willingness-to-pay of USD 100,000/QALY, immediate surgical treatment was the most cost-effective strategy in 64% of iterations.

CONCLUSION

Immediate surgical treatment is a cost-effective strategy for initial management of small UIAs in patients <70 years of age. While more costly than MRA, surgical treatment increased QALY. The cost-effectiveness of immediate surgery is highly sensitive to diagnosis age, rupture rate, and surgical complication risk. Though there are a wide range of rupture rates and complications associated with treatment, this analysis supports the treatment of small, unruptured anterior circulation intracranial aneurysms in patients <70 years of age.

Quantification of the Rupture Potential of Patient-Specific Intracranial Aneurysms under Contact Constraints

Intracranial aneurysms (IAs) are localized enlargements of cerebral blood vessels that cause substantial rates of mortality and morbidity in humans. The rupture possibility of these aneurysms is a critical medical challenge for physicians during treatment planning. This treatment planning while assessing the rupture potential of aneurysms becomes more complicated when they are constrained by an adjacent structure such as optic nerve tissues or bones, which is not widely studied yet. In this work, we considered and studied a constitutive model to investigate the bio-mechanical response of image-based patient-specific IA data using cardiovascular structural mechanics equations. We performed biomechanical modeling and simulations of four different patient-specific aneurysms’ data (three middle cerebral arteries and one internal carotid artery) to assess the rupture potential of those aneurysms under a plane contact constraint. Our results suggest that aneurysms with plane contact constraints produce less or almost similar maximum wall effective stress compared to aneurysms with no contact constraints. In our research findings, we observed that a plane contact constraint on top of an internal carotid artery might work as a protective wall due to the 16.6% reduction in maximum wall effective stress than that for the case where there is no contact on top of the aneurysm.

MR Brain Screening in ADPKD Patients : To Screen or not to Screen?

BACKGROUND

Adult polycystic kidney disease (ADPKD) still represents a major cause of renal failure and intracranial aneurisms (IA) have a higher prevalence in ADPKD than in the general population. Current guidelines suggest performing brain MRI only in the subjects with a positive familiar history of IAs or subarachnoid hemorrhage (SAH). This is a retrospective case-control analysis to evaluate the usefulness of a MR screening program in ADPKD patients.

METHODS

We retrospectively analyzed all ADPKD patients followed in our outpatient clinic between 2016 and 2019 who underwent a brain MRI screening. We evaluated the presence of IAs and others brain abnormalities and compared our results with a non-ADPKD population (n = 300). We performed univariate and multivariate regression analysis to evaluate if general and demographic features, laboratory findings, clinical parameters and genetic test results correlated with IAs or other brain abnormalities presence.

RESULTS

Among the patients evaluated 17 out of 156 (13.6%) ADPKD patients had IAs, compared to 16 out of 300 (5.3%) non-ADPKD controls (p < 0.005). Considering ADPKD patients presenting IAs, 12 (70.6%) had no family history for IAs or SAH. Genetic analysis was available for 97 patients: in the sub-population with IAs, 13 (76.5%) presented a PKD1 mutation and none a PKD2 mutation. We found that arachnoid cysts (AC) (p < 0.001) and arterial anatomical variants (p < 0.04) were significantly more frequent in ADPKD patients.

CONCLUSION

In our population ADPKD patients showed a higher prevalence of IAs, AC and arterial variants compared to non-ADPKD. Most of the IAs were found in patients presenting a PKD1 mutation. We found a significant number of alterations even in those patients without a family history of IAs or SAH. The practice of submitting only patients with familial IAs or kidney transplantation candidates to MRI scan should be re-evaluated.

PHASES score and treatment scoring with cigarette smoking in the long-term prediction of rupturing of unruptured intracranial aneurysms

OBJECTIVE

Treatment indications in unruptured intracranial aneurysms (UIAs) are challenging because of the lack of prospective natural history studies without treatment selection and the decreasing incidence of aneurysm rupture. The purpose of this study was to test whether the population, hypertension, age, size of aneurysm, earlier aneurysm rupture, site of aneurysm (PHASES) score obtained from an individual-based meta-analysis could predict the long-term rupture risk of UIAs.

METHODS

The series included 142 patients of working age with UIAs diagnosed before 1979, when these were not treated but were followed up until the first rupture, death, or the last contact. PHASES scores were recorded for all patients by using the baseline variables and compared with the new treatment score obtained from a recent cohort, consisting of age, smoking status, and aneurysm size and location.

RESULTS

Of the 142 patients, 34 had an aneurysm rupture during a total follow-up of 3064 person-years. The median time between diagnosis and an aneurysm rupture was 10.6 years. The PHASES score at baseline was higher in those with an aneurysm rupture than in the others (5.3 ± 2.3 vs 4.2 ± 2.2, p = 0.012), and the difference relative to the new treatment score was 5.3 ± 2.4 versus 3.0 ± 2.2 (p < 0.001). The receiver operating characteristic curve of the PHASES score for predicting rupture showed a fair area under the curve (0.674, 95% CI 0.558-0.790) where the optimal cutoff point was obtained at ≥ 6 versus < 6 points for sensitivity (0.500) and specificity (0.811). The area under the curve of the new score was 0.755 (95% CI 0.657-0.853), with the optimal cutoff point at ≥ 5 versus < 5 points for sensitivity (0.607) and specificity (0.789).

CONCLUSIONS

The PHASES and the new scores predicted the long-term aneurysm rupture risk moderately well, with the latter, which also included smoking, being slightly better and easier in clinical practice. The findings suggest that treatment decisions about UIAs in patients of working age can be done with an improved cost-effectiveness.

Clipping of unruptured intracranial aneurysms in patients older than sixty: An age-based analysis

OBJECTIVE

The diagnosis of unruptured intracranial aneurysms (UIAs) is being made more frequently in elderly patients. The goal of this study is to evaluate complications and clinical outcome in patients ≥ 60 years-old who underwent clipping of UIAs.

METHODS

We performed a retrospective cohort study. Clinical outcome (modified Rankin scale score) was determined at the latest clinical follow-up. Complications and outcomes were compared between age groups (60-69, 70-80) and subgroups (60-64, 65-69, 70-74, and >75).

RESULTS

The study population consisted of 255 patients (range 60-80 years-old) who underwent 262 clipping procedures for UIAs. Mean follow-up duration was 15.6 months (± 27.5). Major complications occurred in 20 patients (7.6%) and mortality in 3 patients (1.1%). Medical complications occurred in 26 patients (10%). Mean length of hospital-stay was 4.7 days (± 5.8). 89.6% were discharged to home. 87.8% had a favorable clinical outcome. The 70-80 age group had significantly more complications (P = 0.03) than the 60-69 group and a significantly longer hospital stay (6.02 vs. 4.3 days, P = 0.04). The older group was less likely to discharge to home and more likely to require rehabilitation (P = 0.002). Favorable clinical outcome did not significantly differ between the two groups (85.7% vs. 88.4%, P = 0.56). There was a trend for increasing complications from the younger to older subgroups (P = 0.008) and a reduction in the likelihood to discharge to home (P < 0.0001). The rate of ultimate favorable clinical outcome did not differ significantly between subgroups (P = 0.79).

CONCLUSION

Although complications, length of hospital-stay, and discharge to non-home destinations increase with older age, the majority of patients ≥ 60 may have favorable clinical outcomes.

Outcome of Patients with Multiple Intracranial Aneurysms after Subarachnoid Hemorrhage and Future Risk of Rupture of Unruptured Aneurysm

The purpose was to study the risk of rupture of unruptured intracranial aneurysms (UIAs) of patients with multiple intracranial aneurysms after subarachnoid hemorrhage (SAH), in a long-term follow-up study, from variables known at baseline. Future rupture risk was compared in relation to outcome after SAH. The series consists of 131 patients with 166 UIAs and 2854 person-years of follow-up between diagnosis of UIA and its rupture, death or the last follow-up contact. These were diagnosed before 1979, when UIAs were not treated in our country. Those patients with a moderate or severe disability after SAH, according to the Glasgow Outcome Scale, had lower rupture rates of UIA than those with a good recovery or minimal disability (4/37 or 11%, annual UIA rupture rate of 0.5% (95% confidence interval (CI) 0.1-1.3%) during 769 follow-up years vs. 27/94 or 29%, 1.3% (95% CI 0.9-1.9%) during 2085 years). Those with a moderate or severe disability differed from others by their older age. Those with a moderate or severe disability tended to have a decreased cumulative rate of aneurysm rupture (log rank test, p = 0.066) and lower relative risk of UIA rupture (hazard ratio 0.39, 95% CI 0.14-1.11, p = 0.077). Multivariable hazard ratios showed at least similar results, suggesting that confounding factors did not have a significant effect on the results. The results of this study without treatment selection of UIAs suggest that patients with a moderate or severe disability after SAH have a relatively low risk of rupture of UIAs. Their lower treatment indication may also be supported by their known higher treatment risks.

Nature, content and shifts over time of the most impactful unruptured intracranial aneurysms articles: a bibliometric analysis

BACKGROUND

The management of unruptured intracranial aneurysms (UIAs) has evolved significantly over the last few decades. Our objective was to evaluate the 100 most cited UIA articles by bibliometric analysis to identify nature, content and shifts over time.

METHODS

Elsevier's Scopus database was interrogated for the 100 most cited articles that focused on UIA. Older versus newer articles were compared, with categorical data analyzed using Pearson's Chi-square, and continuous data analyzed using Wilcoxon's rank-sum test.

RESULTS

The 100 most cited articles were published between 1975 and 2015, with the majority of these reporting patient clinical outcomes (n=69). There were 47/69 (68%) articles that described surgical intervention, with 38/47 (81%) and 18/47 (38%) including endovascular and open approaches, respectively . Publications peaked in 2004 (n=8), and the most common country of correspondence was the United States (n=59). Compared to older articles, newer articles had statistically higher citation rates (P<0.01), higher number of authors (P<0.01) with more multiple institution collaborations (P=0.01), greater disclosures of funding (P<0.01), more focus on endovascular treatments (P=0.04), in more journals with a clinical, non-surgical focus (P<0.01) published under open access policies (P<0.01).

CONCLUSIONS

In the 100 most cited articles about UIAs to date, there is a distinct shift towards more co-authored efforts utilizing multi-institutional efforts focused on endovascular approaches supported by funding. The emergence of endovascular techniques has refreshed the need for more contemporary rupture risk prediction models and natural history data to validate current attitudes towards clinical management after these minimally invasive procedures for UIAs.

Adaptive Remodeling in the Elastase-induced Rabbit Aneurysms

BACKGROUND

Rupture of brain aneurysms is associated with high fatality and morbidity rates. Through remodeling of the collagen matrix, many aneurysms can remain unruptured for decades, despite an enlarging and evolving geometry.

OBJECTIVE

Our objective was to explore this adaptive remodeling for the first time in an elastase induced aneurysm model in rabbits.

METHODS

Saccular aneurysms were created in 22 New Zealand white rabbits and remodeling was assessed in tissue harvested 2, 4, 8 and 12 weeks after creation.

RESULTS

The intramural principal stress ratio doubled after aneurysm creation due to increased longitudinal loads, triggering a remodeling response. A distinct wall layer with multi-directional collagen fibers developed between the media and adventitia as early as 2 weeks, and in all cases by 4 weeks with an average thickness of 50.6 ± 14.3 μm. Collagen fibers in this layer were multi-directional (AI = 0.56 ± 0.15) with low tortuosity (1.08 ± 0.02) compared with adjacent circumferentially aligned medial fibers (AI = 0.78 ± 0.12) and highly tortuous adventitial fibers (1.22 ± 0.03). A second phase of remodeling replaced circumferentially aligned fibers in the inner media with longitudinal fibers. A structurally motivated constitutive model with both remodeling modes was introduced along with methodology for determining material parameters from mechanical testing and multiphoton imaging.

CONCLUSIONS

A new mechanism was identified by which aneurysm walls can rapidly adapt to changes in load, ensuring the structural integrity of the aneurysm until a slower process of medial reorganization occurs. The rabbit model can be used to evaluate therapies to increase aneurysm wall stability.

Performance of Radiomics derived morphological features for prediction of aneurysm rupture status

BACKGROUND

Morphological differences between ruptured and unruptured cerebral aneurysms represent a focus of neuroimaging researchfor understanding the mechanisms of aneurysmal rupture. We evaluated the performance of Radiomics derived morphological features, recently proposed for rupture status classification, against automatically measured shape and size features previously established in the literature.

METHODS

353 aneurysms (123 ruptured) from three-dimensional rotational catheter angiography (3DRA) datasets were analyzed. Based on a literature review, 13 Radiomics and 13 established morphological descriptors were automatically extracted per aneurysm, and evaluated for rupture status prediction using univariate and multivariate statistical analysis, yielding an area under the curve (AUC) metric of the receiver operating characteristic.

RESULTS

Validation of overlapping descriptors for size/volume using both methods were highly correlated (p<0.0001, R ²=0.99). Univariate analysis selected AspectRatio (p<0.0001, AUC=0.75), Non-sphericity Index (p<0.0001, AUC=0.75), Height/Width (p<0.0001, AUC=0.73), and SizeRatio (p<0.0001, AUC=0.73) as best among established descriptors, and Elongation (p<0.0001, AUC=0.71) and Flatness (p<0.0001, AUC=0.72) among Radiomics features. Radiomics Elongation correlated best with established Height/Width (R ²=0.52), whereas Radiomics Flatness correlated best with Ellipticity Index (R ²=0.54). Radiomics Sphericity correlated best with Undulation Index (R ²=0.65). Best Radiomics performers, Elongation and Flatness, were highly correlated descriptors (p<0.0001, R ²=0.75). In multivariate analysis, established descriptors (Height/Width, SizeRatio, Ellipticity Index; AUC=0.79) outperformed Radiomics features (Elongation, Maximum3Ddiameter; AUC=0.75).

CONCLUSION

Although recently introduced Radiomics analysis for aneurysm shape and size evaluation has the advantage of being an efficient operator independent methodology, it currently offers inferior rupture status discriminant performance compared with established descriptors. Future research is needed to extend the current Radiomics feature set to better capture aneurysm shape information.

Scoring of Growth of Unruptured Intracranial Aneurysms

The purpose was to obtain a reliable scoring for growth of unruptured intracranial aneurysms (UIAs) in a long-term follow-up study from variables known at baseline and to compare it with the ELAPSS (Earlier subarachnoid hemorrhage, Location of the aneurysm, Age > 60 years, Population, Size of the aneurysm, and Shape of the aneurysm) score obtained from an individual-based meta-analysis. The series consists of 87 patients with 111 UIAs and 1669 person-years of follow-up between aneurysm size measurements (median follow-up time per patient 21.7, range 1.2 to 51.0 years). These were initially diagnosed between 1956 and 1978, when UIAs were not treated in our country. ELAPSS scores at baseline did not differ between those with and those without aneurysm growth. The area under the curve (AUC) for the receiver operating curve (ROC) of the ELAPSS score for predicting long-term growth was fail (0.474, 95% CI 0.345–0.603), and the optimal cut-off point was obtained at ≥7 vs. <7 points for sensitivity (0.829) and specificity (0.217). In the present series UIA growth was best predicted by female sex (4 points), smoking at baseline (3 points), and age <40 years (2 points). The AUC for the ROC of the new scoring was fair (0.662, 95% CI 0.546–0.779), which was significantly better than that of ELAPSS score (p < 0.05). The optimal cut-off point was obtained at ≥4 vs. <4 points for sensitivity (0.971) and specificity (0.304). A new simple scoring consisting of only female sex, cigarette smoking and age <40 years predicted growth of an intracranial aneurysm in long-term follow-up, significantly better than the ELAPSS score.

A Simple Flow Classification Parameter Can Discriminate Rupture Status in Intracranial Aneurysms

BACKGROUND

A simple dimensionless aneurysm number ($An$), which depends on geometry and flow pulsatility, was previously shown to distinguish the flow mode in intracranial aneurysms (IA): vortex mode with a dynamic vortex formation/evolution if $An > 1$, and cavity mode with a steady shear layer if $An < 1$.

OBJECTIVE

To hypothesize that $An\ > \ 1$ can distinguish rupture status because vortex mode is associated with high oscillatory shear index, which, in turn, is statistically associated with rupture.

METHODS

The above hypothesis is tested on a retrospective, consecutively collected database of 204 patient-specific IAs. The first 119 cases are assigned to training and the remainder to testing dataset. $An$ is calculated based on the pulsatility index (PI) approximated either from the literature or solving an optimization problem (denoted as$\ \widehat {PI}$). Student's t-test and logistic regression (LR) are used for hypothesis testing and data fitting, respectively.

RESULTS

$An$ can significantly discriminate ruptured and unruptured status with 95% confidence level (P < .0001). $An$ (using PI) and $\widehat {An}$ (using $\widehat {PI}$) significantly predict the ruptured IAs (for training dataset $An\!:\ $AUC = 0.85, $\widehat {An}\!:\ $AUC = 0.90, and for testing dataset $An\!:\ $sensitivity = 94%, specificity = 33%, $\widehat {An}\!:\ $sensitivity = 93.1%, specificity = 52.85%).

CONCLUSION

$An > 1$ predicts ruptured status. Unlike traditional hemodynamic parameters such as wall shear stress and oscillatory shear index, $An$ has a physical threshold of one (does not depend on statistical analysis) and does not require time-consuming flow simulations. Therefore, $An$ is a simple, practical discriminator of IA rupture status.

Safety of Aspirin Use in Patients With Stroke and Small Unruptured Aneurysms

OBJECTIVE

We initiated a multicenter, prospective cohort study to test the hypothesis that aspirin is safe for patients with ischemic cerebrovascular disease (ICVD) harboring unruptured intracranial aneurysms (UIAs) <7 mm.

METHODS

This prospective, multicenter cohort study consecutively enrolled 1,866 eligible patients with ICVD harboring UIAs <7 mm in diameter from 4 hospitals between January 2016 and August 2019. Baseline and follow-up patient information, including the use of aspirin, was recorded. The primary endpoint was aneurysm rupture.

RESULTS

After a total of 4,411.4 person-years, 643 (37.2%) patients continuously received aspirin treatment. Of all included patients, rupture occurred in 12 (0.7%). The incidence rate for rupture (IRR) was 0.27 (95% confidence interval [CI] 0.15-0.48) per 100 person-years. The IRRs were 0.39 (95% CI 0.21-0.72) and 0.06 (95% CI 0.010-0.45) per 100 person-years for the nonaspirin and aspirin groups, respectively. In the multivariate analysis, uncontrolled hypertension and UIAs 5 to <7 mm were associated with a high rate of aneurysm rupture, whereas aspirin use was associated with a low rate of aneurysm rupture. Compared with other groups, the high-risk group (UIAs 5 to <7 mm with concurrent uncontrolled hypertension) without aspirin had higher IRRs.

CONCLUSION

Aspirin is a safe treatment for patients with concurrent small UIAs and ICVD. Patients who are not taking aspirin in the high-risk group warrant intensive surveillance.

CLINICALTRIALSGOV IDENTIFIER

NCT02846259.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for patients harboring UIAs <7 mm with ICVD, aspirin does not increase the risk of aneurysm rupture.

Increased rupture risk in small intracranial aneurysms associated with methamphetamine use

BACKGROUND

Aneurysmal subarachnoid hemorrhage (SAH) is the most common cause of nontraumatic SAH. Current guidelines generally recommend observation for unruptured intracranial aneurysms smaller than 7 mm, for those are considered at low risk for spontaneous rupture according to available scoring systems.

OBJECTIVE

We observed a tendency for SAH in small intracranial aneurysms in patients who are methamphetamine users. A retrospective, single center study to characterize the size and location of ruptured and unruptured intracranial aneurysms in methamphetamine users was performed.

MATERIALS AND METHODS

Clinical characteristics and patient data were collected via retrospective chart review of patients with intracranial aneurysms and a history of methamphetamine use with a specific focus on aneurysm size and location.

RESULTS

A total of 62 patients were identified with at least one intracranial aneurysm and a history of methamphetamine use, yielding 73 intracranial aneurysms (n = 73). The mean largest diameter of unruptured aneurysms (n = 44) was 5.1 mm (median 4.5, SD 2.5 mm), smaller than for ruptured aneurysms (n = 29) with a mean diameter of 6.3 mm (median 5.5, SD 2.5 mm). Aneurysms measuring less than 7 mm presented with SAH in 36.5%. With regard to location, 28% (n = 42) of anterior circulation aneurysms less than 7 mm presented with rupture, in contrast to 70% (n = 10) of posterior circulation aneurysms which were found to be ruptured.

CONCLUSIONS

Methamphetamine use may be considered a significant risk factor for aneurysmal SAH at a smaller aneurysm size than for other patients. These patients may benefit from a lower threshold for intervention and/or aggressive imaging and clinical follow-up.

Cigarette smoking and risk of intracranial aneurysms in middle-aged women

BACKGROUND AND PURPOSE

We previously reported a single-centre study demonstrating that smoking confers a six-fold increased risk for having an unruptured intracranial aneurysm (UIA) in women aged between 30 and 60 years and this risk was higher if the patient had chronic hypertension. There are no data with greater generalisability evaluating this association. We aimed to validate our previous findings in women from a multicentre study.

METHODS

A multicentre case-control study on women aged between 30 and 60 years, that had magnetic resonance angiography (MRA) during the period 2016-2018. Cases were those with an incidental UIA, and these were matched to controls based on age and ethnicity. A multivariable conditional logistic regression was conducted to evaluate smoking status and hypertension differences between cases and controls.

RESULTS

From 545 eligible patients, 113 aneurysm patients were matched to 113 controls. The most common reason for imaging was due to chronic headaches in 62.5% of cases and 44.3% of controls. A positive smoking history was encountered in 57.5% of cases and in 37.2% of controls. A multivariable analysis demonstrated a significant association between positive smoking history (OR 3.7, 95%CI 1.61 to 8.50), hypertension (OR 3.16, 95% CI 1.17 to 8.52) and both factors combined with a diagnosis of an incidental UIA (OR 6.9, 95% CI 2.49 to 19.24).

CONCLUSIONS

Women aged between 30 and 60 years with a positive smoking history have a four-fold increased risk for having an UIA, and a seven-fold increased risk if they have underlying chronic hypertension. These findings indicate that women aged between 30 and 60 years with a positive smoking history might benefit from a screening recommendation.

Shape irregularity of the intracranial aneurysm lumen exhibits diagnostic value

BACKGROUND

Morphological irregularity is linked to intracranial aneurysm wall instability and manifests in the lumen shape. Yet there is currently no consent on how to assess shape irregularity. The aims of this work are to quantify irregularity as perceived by clinicians, to break down irregularity into morphological attributes, and to relate these to clinically relevant factors such as rupture status, aneurysm location, and patient age or sex.

METHODS

Thirteen clinicians and 26 laypersons assessed 134 aneurysm lumen segmentations in terms of overall perceived irregularity and five different morphological attributes (presence/absence of a rough surface, blebs, lobules, asymmetry, complex geometry of the parent vasculature). We examined rater agreement and compared the ratings with clinical factors by means of regression analysis or binary classification.

RESULTS

Using rank-based aggregation, the irregularity ratings of clinicians and laypersons did not differ statistically. Perceived irregularity showed good agreement with curvature (coefficient of determination R² = 0.68 ± 0.08) and was modeled very accurately using the five morphological rating attributes plus shape elongation (R² = 0.95 ± 0.02). In agreement with previous studies, irregularity was associated with aneurysm rupture status (AUC = 0.81 ± 0.08); adding aneurysm location as an explanatory variable increased the AUC to 0.87 ± 0.09. Besides irregularity, perceived asymmetry, presence of blebs or lobules, aneurysm size, non-sphericity, and curvature were linked to rupture. No association was found between morphology and any of patient sex, age, and history of smoking or hypertension. Aneurysm size was linked to morphology.

CONCLUSIONS

Irregular lumen shape carries significant information on the aneurysm's disease status. Irregularity constitutes a continuous parameter that shows a strong association with the rupture status. To improve the objectivity of morphological assessment, we suggest examining shape through six different morphological attributes, which can characterize irregularity accurately.

LATE ANEURYSM RELAPSE AFTER MICROSURGICAL TREATMENT OF MIDDLE CEREBRAL ARTERY ANEURYSM: A CASE REPORT AND LITERATURE REVIEW OF TREATMENT OPTIONS

Recurrence of intracranial aneurysm after initial microsurgical or endovascular treatment is uncommon. Although the exact etiology remains unknown, recurrent aneurysms may be observed in surgical patients with big and multiple aneurysms, arterial hypertension, non-atherosclerotic cerebrovascular arteriopathies, as well as in those with a familial history of the disease. Such recurrence can occur over a wide period ranging from several months to years after the initial aneurysm treatment. Still, the occurrence delayed by more than 20 years is rather unusual. Herein, we present a case of a 70-year-old female patient who developed late intracranial aneurysm relapse 30 years after successful microsurgical clipping of the middle cerebral artery aneurysm. We also provide a brief review of relevant literature, discussing the etiology and pathophysiology of aneurysm reappearance, as well as different treatment options available. In conclusion, one should always consider the possibility of intracranial aneurysm recurrence regardless of the mode and time of primary surgery. In such a case, a multidisciplinary management approach using flow diverting endovascular techniques is advised in selected patients.

Pointwise encoding time reduction with radial acquisition in subtraction-based magnetic resonance angiography to assess saccular unruptured intracranial aneurysms at 3 Tesla

PURPOSE

To investigate the clinical utility of pointwise encoding time reduction with radial acquisition in subtraction-based magnetic resonance angiography (PETRA-MRA) and time-of-flight magnetic resonance angiography (TOF-MRA) to evaluate saccular unruptured intracranial aneurysms (UIAs).

METHODS

A total of 49 patients with 54 TOF-MRA-identified saccular UIAs were enrolled. The morphologic parameters, contrast-to-noise-ratios (CNRs), and sharpness of aneurysms were measured using PETRA-MRA and TOF-MRA. Two radiologists independently evaluated subjective image scores, focusing on aneurysm signal homogeneities and sharpness depictions using a 4-point scale: 4, excellent; 3, good; 2, poor; 1, not assessable. PETRA-MRA and TOF-MRA acoustic noises were measured.

RESULTS

All aneurysms were detected with PETRA-MRA. The morphologic parameters of 15 patients evaluated with PETRA-MRA were more closely correlated with those receiving computed tomography angiography over those receiving TOF-MRA. No significant differences between PETRA-MRA and TOF-MRA parameters were seen in the 54 UIAs (p > 0.10), excluding those with inflow angles (p < 0.05). In four patients with inflow angles on PETRA-MRA, the angles were more closely related to those of digital subtraction angiography than those of TOF-MRA. CNRs between TOF-MRA and PETRA-MRA were comparable (p = 0.068), and PETRA-MRA sharpness values and subjective image scores were significantly higher than those of TOF-MRA (p < 0.001). Inter-observer agreements were excellent for both PETRA-MRA and TOF-MRA (intraclass correlation coefficients were 0.90 and 0.97, respectively). The acoustic noise levels of PETRA-MRA were much lower than those of TOF-MRA (59 vs.73 dB, p < 0.01).

CONCLUSIONS

PETRA-MRA, with better visualization of aneurysms and lower acoustic noise levels than TOF-MRA, showed a superior diagnostic performance for depicting saccular UIAs.

Women With First-Hand Tobacco Smoke Exposure Have a Higher Likelihood of Having an Unruptured Intracranial Aneurysm Than Nonsmokers: A Nested Case-Control Study

BACKGROUND

The prevalence of unruptured intracranial aneurysms (UIA) in females who smoke cigarettes and the association between smoking and hypertension with purely incidental UIAs have been unexplored.

OBJECTIVE

To obtain the prevalence of UIA among females and to assess the relationship between smoking and hypertension with a diagnosis of incidental UIAs.

METHODS

A nested case-control study from a cohort of female patients aged between 30 and 60 yr with a brain magnetic resonance angiography (MRA) between 2016 and 2018. Incidental UIAs were compared to patients with normal MRAs. Smoking was characterized as never or former/current smokers. A logistic regression was used to evaluate the association between smoking, hypertension, or both, with a diagnosis of incidental UIAs.

RESULTS

A total of 1977 patients had a brain MRA between 2016 and 2018. From 1572 nonsmoker patients, we encountered 30 with an UIA (prevalence: 1.9%). There were 405 patients with a positive smoking history, and 77 patients harbored an UIA (prevalence: 19%). Of 64 aneurysm patients and 130 random controls eligible for the case control, aneurysm patients were more likely to have a positive smoking history and hypertension compared with healthy controls (60% vs 18%, P ≤ .001; 44% vs 14%, P ≤ .001). A multivariable analysis demonstrated a significant association between a smoking history, hypertension, or both factors with an incidental UIA (odds ratio [OR] 5.8 CI 1.22-11.70; OR 3.8 CI 2.31-14.78; OR 12.6 CI 4.38-36.26; respectively).

CONCLUSION

Females who smoke cigarettes have a higher prevalence of UIAs than the general population. Smoking confers a higher risk for having a silent UIA, aggravated by hypertension. This population is an ideal target for potential screening.

Ratio of IL-8 in CSF versus Serum Is Elevated in Patients with Unruptured Brain Aneurysm

Only scarce data pertaining to interleukin 8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) chemokines in human aneurysm can be found in the current literature. Therefore, the aim of this study was the evaluation of cerebrospinal fluid (CSF) and serum IL-8 and MCP-1 concentration in unruptured intracranial aneurysm (UIA) patients (n = 25) compared to the control group (n = 20). IL-8 and MCP-1 concentrations were measured with ELISA method. We demonstrated that CSF IL-8 concentration of UIA patients is significantly higher (p < 0.001) than that presented in the serum, which can indicate its local synthesis within central nervous system. CSF IL-8 concentration was also significantly related to aneurysm size, which may reflect the participation of IL-8 in the formation and development of brain aneurysms. IL-8 Quotient (CSF IL-8 divided by serum IL-8) in UIA patients was statistically higher compared to control individuals (p = 0.045). However, the diagnostic utility analysis did not equivocally indicate the diagnostic usefulness of the IL-8 Quotient evaluation in brain aneurysm patients. Nevertheless, this aspect requires further study.

Endovascular Temporary Balloon Occlusion for Microsurgical Clipping of Posterior Circulation Aneurysms

Based on the relationship between the posterior clinoid process and the basilar artery (BA) apex it may be difficult to obtain proximal control of the BA using temporary clips. Endovascular BA temporary balloon occlusion (TBO) can reduce aneurysm sac pressure, facilitate dissection/clipping, and finally lower the risk of intraoperative rupture. We present our experience with TBO during aneurysm clipping of posterior circulation aneurysms within the setting of a hybrid operating room (hOR). We report one case each of a basilar tip, posterior cerebral artery, and superior cerebellar artery aneurysm that underwent surgical occlusion under TBO within an hOR. Surgical exposure of the BA was achieved with a pterional approach and selective anterior and posterior clinoidectomy. Intraoperative digital subtraction angiography (iDSA) was performed prior, during, and after aneurysm occlusion. Two patients presented with subarachnoid hemorrhage and one patient presented with an unruptured aneurysm. The intraluminal balloon was inserted through the femoral artery and inflated in the BA after craniotomy to allow further dissection of the parent vessel and branches needed for the preparation of the aneurysm neck. No complications during balloon inflation and aneurysm dissection occurred. Intraoperative aneurysm rupture prior to clipping did not occur. The duration of TBO varied between 9 and 11 min. Small neck aneurysm remnants were present in two cases (BA and PCA). Two patients recovered well with a GOS 5 after surgery and one patient died due to complications unrelated to surgery. Intraoperative TBO within the hOR is a feasible and safe procedure with no additional morbidity when using a standardized protocol and setting. No relevant side effects or intraoperative complications were present in this series. In addition, iDSA in an hOR facilitates the evaluation of the surgical result and 3D reconstructions provide documentation of potential aneurysm remnants for future follow-up.

Contemporaneous Clipping of Unruptured Anterior Cerebral Artery Proximal A1 Segment Aneurysm and Resection of Dural-Based Brain Tumor

The coexistence of brain tumors and unruptured intracranial aneurysms is uncommon, so there is limited data regarding management strategies for these cases. Tumor, aneurysm, and patient factors must be considered in the decision-making process. We present a case of a dural-based left temporal brain tumor with an incidental ipsilateral unruptured anterior cerebral artery (ACA) proximal A1 segment aneurysm.

A 56-year-old female presented with progressive headaches and convulsions without focal neurological deficits. Neuroimaging showed a large dural-based left temporal tumor with adjacent vasogenic edema. The patient underwent a cerebral angiography for preoperative tumor embolization, which revealed a small, unruptured intracranial aneurysm arising from the left ACA proximal A1 segment. We performed a left frontotemporal craniotomy for concurrent resection of the dural-based tumor and clipping of the left A1 aneurysm. She elected to proceed, so she underwent a left-sided craniotomy for tumor resection and clipping of the aneurysm. Postoperatively, the patient developed transient, mild right-sided hemiparesis from a left anterior thalamic infarct that resolved before discharge. Follow-up brain magnetic resonance imaging and catheter cerebral angiography showed gross total resection of the tumor and complete aneurysm obliteration, respectively. Patients with dual diagnoses of a brain tumor and intracranial aneurysm can be challenging to manage. When intervention is indicated for each lesion and both can be safely accessed from the same operative approach, contemporaneous surgical treatment of the tumor and aneurysm is reasonable in appropriately selected cases.

Management of incidentally found unruptured intracranial aneurysms

Incidentally found unruptured intracranial aneurysms are increasing because of the popularity of medical checkups with cerebrovascular imaging and the recent growing interest in health. Accordingly, surgical or endovascular treatments are also increasing in prevalence to improve aneurysm-related symptoms or prevent the rupture of aneurysms causing devastating conditions. However, treatment plans should be carefully determined based on the natural history of aneurysms, comorbidities of the patients, and institutional situations because of the relatively low risk of rupture, no uncommon treatment-related complications, and considerable economical and psychological burdens. Recently, domestic and international clinical guidelines for unruptured intracranial aneurysms were introduced, and the guidelines have been continuously revised according to advancements in imaging and treatment techniques. Here, this review paper introduces the clinical characteristics of unruptured intracranial aneurysms including the epidemiology, risk factors of development, growth and rupture, natural course, symptoms and signs, imaging tools for diagnosis and follow-up, and treatment methods. This paper also includes recent international prospective trials, analytic reports with big data from national health insurance and health insurance review and assessment services, and the guidelines of Korea and other foreign countries.

Low Rank and Sparse Decomposition of Ultrasound Color Flow Images for Suppressing Clutter in Real-Time

In this work, a novel technique for real-time clutter rejection in ultrasound Color Flow Imaging (CFI) is proposed. Suppressing undesired clutter signal is important because clutter prohibits an unambiguous view of the vascular network. Although conventional eigen-based filters are potentially efficient in suppressing clutter signal, their performance is highly dependent on proper selection of a clutter to blood boundary which is done manually. Herein, we resolve this limitation by formulating the clutter suppression problem as a foreground-background separation problem to extract the moving blood component. To that end, we adapt the fast Robust Matrix Completion (fRMC) algorithm, and utilize the in-face extended Frank-Wolfe method to minimize the rank of the matrix of ultrasound frames. Our method automates the clutter suppression process, which is critical for clinical use. We name the method RAPID (Robust mAtrix decomPosition for suppressIng clutter in ultrasounD) since the automation step can substantially streamline clutter suppression. The technique is validated with simulation, flow phantom and two sets of in-vivo data. RAPID code as well as most of the data in this paper can be downloaded from RAPID.sonography.ai.

Decompressive Craniectomy: the Right Call at the Right Moment

Introduction:Massive intracerebral hemorrhages and large internal carotid artery infarcts may cause early death due to severe cerebral edema with elevated intracranial pressure, despite maximal medical therapy. Decompressive craniectomy may be of benefit to these patients in terms of survival and even functional outcome. The aim of our paper is to present two cases that illustrate the use of decompressive craniectomy both in ischemic and hemorrhagic stroke, followed by a discussion on the indication and right timing of the intervention, but also on the outcome of these patients. Materials and methods: We present the cases of a 38-year-old man with a right lenticular and capsular hemorrhage who underwent decompressive craniectomy in the first 24 hours from onset of symptoms and a 64-year-old patient with an ischemic stroke in the territory of the left carotid artery with a decompressive craniectomy performed at more than 72 hours from the beginning. For each of the two cases, we analyzed the following parameters: neurologic status, Glasgow Coma Scale, aspect of the cerebral computed tomography before and after surgery, in-hospital complications and modified Rankin Scale at discharge. Outcomes: While the intervention was life-saving in both cases, the procedure had different functional outcomes. Conclusion: Decompressive craniectomy may be a life-saving procedure for patients with both hemorrhagic or ischemic strokes complicated with massive edema and increased intracranial pressure. When performed in the first 48 hours, especially in patients with ischemic stroke aged less than 60, it may also improve the functional outcome compared to conservative treatment.

Association between aneurysm hemodynamics and wall enhancement on 3D vessel wall MRI

OBJECTIVE

Aneurysm wall enhancement (AWE) on 3D vessel wall MRI (VWMRI) has been suggested as an imaging biomarker for intracranial aneurysms (IAs) at higher risk of rupture. While computational fluid dynamics (CFD) studies have been used to investigate the association between hemodynamic forces and rupture status of IAs, the role of hemodynamic forces in unruptured IAs with AWE is poorly understood. The authors investigated the role and implications of abnormal hemodynamics related to aneurysm pathophysiology in patients with AWE in unruptured IAs.

METHODS

Twenty-five patients who had undergone digital subtraction angiography (DSA) and VWMRI studies from September 2016 to September 2017 were included, resulting in 22 patients with 25 IAs, 9 with and 16 without AWE. High-resolution CFD models of hemodynamics were created from DSA images. Univariate and multivariate analyses were performed to investigate the association between AWE and conventional morphological and hemodynamic parameters. Normalized MRI signal intensity was quantified and quantitatively associated with wall shear stresses (WSSs) for the entire aneurysm sac, and in regions of low, intermediate, and high WSS.

RESULTS

The AWE group had lower WSS (p < 0.01) and sac-averaged velocity (p < 0.01) and larger aneurysm size (p < 0.001) and size ratio (p = 0.0251) than the non-AWE group. From multivariate analysis of both hemodynamic and morphological factors, only low WSS was found to be independently associated with AWE. Sac-averaged normalized MRI signal intensity correlated with WSS and was significantly different in regions of low WSS compared to regions of intermediate (p = 0.018) and high (p < 0.001) WSS.

CONCLUSIONS

The presence of AWE was associated with morphological and hemodynamic factors related to rupture risk. Low WSS was found to be an independent predictor of AWE. Our findings support the hypothesis that low WSS in IAs with AWE may indicate a growth and remodeling process that may predispose such aneurysms to rupture; however, a causality between the two cannot be established.

The Relationship Between Obstructive Sleep Apnea and Ruptured Intracranial Aneurysms

STUDY OBJECTIVES

The role of obstructive sleep apnea (OSA) in the overall outcome of ruptured intracranial aneurysms (RIAs) is unknown. We have investigated the role of OSA in overall outcome of RIAs.

METHODS

Data from 159 consecutive patients were retrospectively reviewed. A chi-square test and regression analysis were performed to determine the significant difference. A value of P < .05 was considered significant.

RESULTS

The prevalence of OSA in RIAs was fivefold higher in the nonaneurysm patient group, P = .002. The number of patients with hypertension (P < .0001), body mass index ≥ 30 (P < .0001), hyperlipidemia (P = .018), chronic heart disease (P = .002) or prior ischemic stroke (P = .001) was significantly higher in the OSA group. Similarly, the number of wide-neck aneurysms (P < .0001) and aneurysm > 7 mm (P = .004), poor Hunt and Hess grade IV-V (P = .005), vasospasms, (P = .03), and patients with poor Modified Rankin Scale scores (3-6) was significantly higher in the OSA group (P < .0001). Interestingly, for the first time in univariate (P = .01) and multivariate (P = .003) regression analysis, OSA was identified as an individual predictor of unfavorable outcome of RIAs. In addition, hypertension (P = .04), smoking (P = .049), chronic heart disease (P = .01), and Hunt and Hess grade IV-V (P = .04) were revealed as predictors of poor outcome of RIAs.

CONCLUSIONS

This is a novel study to determine the association between OSA and ruptured cerebral aneurysm in terms of comorbidities, size of aneurysm, severity of symptoms, and outcomes after treatment. In addition, for the first time, OSA is identified as a positive predictor of unfavorable outcome of RIAs.

Unruptured Giant Intracerebral Aneurysms: Serious Trouble Requiring Serious Treatment - Case Report and Literature Review

Giant intracranial aneurysms (ICGA) represent 3 to 5% of all intracranial aneurysms in adults. They are defined as arterial dilatations, with more than 25 mm in diameter. Despite important advances in the research of endovascular techniques of treating giant intracranial aneurysms, the management of these vascular malformations still poses great difficulties for neurologists and interventional radiologists. In particular, these challenges arise from the difficult and modified cerebral anatomy of patients with ICGA. Choosing the best treatment for patients with ICGA involves not only finding the perfect balance between the potential risks and benefits of endovascular treatment, but also taking into consideration the patient's biological condition and associated diseases. The aim of this paper is to describe the decisional algorithm of treating patients with giant intracranial aneurysms and factors which could influence the choice of endovascular technique. We report a clinical case of a 63-year-old female with cardio-vascular risk factors (atrial fibrillation, high blood pressure), diagnosed with a symptomatic giant aneurysm of the right internal carotid artery and multiple cerebral micro-bleeds. Given the very large size of the aneurysm, its characteristics as well as patient's associated comorbidities, it was decided to exclude the ICA aneurysm from circulation by occluding the parent vessel (right internal carotid artery) by using endovascular techniques. Also, a review of the literature on the currently available endovascular methods for treating patients with giant intracranial aneurysms was performed in order to see the indications and possible long-term complications of each method. In selected cases, the risks of serious complications associated with occluding a large cervical-cerebral vessel (as the internal carotid artery) are far exceeded by the risk for rupture of giant aneurysms, which is fatal in many cases. Nevertheless, it is of utmost importance to mention that, although the use of endovascular methods leads to a significant increase in life expectancy, a severe decline in quality of life might be experienced by these patients.

Interactive exploration of a 3D intracranial aneurysm wall model extracted from histologic slices

PURPOSE

Currently no detailed in vivo imaging of the intracranial vessel wall exists. Ex vivo histologic images can provide information about the intracranial aneurysm (IA) wall composition that is useful for the understanding of IA development and rupture risk. For a 3D analysis, the 2D histologic slices must be incorporated in a 3D model which can be used for a spatial evaluation of the IA's morphology, including analysis of the IA neck.

METHODS

In 2D images of histologic slices, different wall layers were manually segmented and a 3D model was generated. The nuclei were automatically detected and classified as round or elongated, and a neural network-based wall type classification was performed. The information was combined in a software prototype visualization providing a unique view of the wall characteristics of an IA and allowing interactive exploration. Furthermore, the heterogeneity (as variance of the wall thickness) of the wall was evaluated.

RESULT

A 3D model correctly representing the histologic data was reconstructed. The visualization integrating wall information was perceived as useful by a medical expert. The classification produces a plausible result.

CONCLUSION

The usage of histologic images allows to create a 3D model with new information about the aneurysm wall. The model provides information about the wall thickness, its heterogeneity and, when performed on cadaveric samples, includes information about the transition between IA neck and sac.

Observed rupture of unruptured intracranial aneurysms

Aim: To study the aneurysms where pre and post-rupture imaging was available to determine the impact of rupture on morphology and size of the aneurysm.Methods: A retrospective case series where all cases of ruptured aneurysms over a 5-year period were evaluated and cases identified where pre and post rupture imaging was available. These were then studied in detail.Results: The actual change in the volume of the aneurysm pre and post rupture was quite small and the underlying shape/morphology did not change at all.Conclusion: Post-rupture morphology of aneurysms can be used as representative of pre-rupture morphology. Further larger studies in collaboration with other neurosurgical centres to corroborate this view would be helpful.

Multiscale composite model of fiber-reinforced tissues with direct representation of sub-tissue properties

In many fiber-reinforced tissues, collagen fibers are embedded within a glycosaminoglycan-rich extrafibrillar matrix. Knowledge of the structure-function relationship between the sub-tissue properties and bulk tissue mechanics is important for understanding tissue failure mechanics and developing biological repair strategies. Difficulties in directly measuring sub-tissue properties led to a growing interest in employing finite element modeling approaches. However, most models are homogeneous and are therefore not sufficient for investigating multiscale tissue mechanics, such as stress distributions between sub-tissue structures. To address this limitation, we developed a structure-based model informed by the native annulus fibrosus structure, where fibers and the matrix were described as distinct materials occupying separate volumes. A multiscale framework was applied such that the model was calibrated at the sub-tissue scale using single-lamellar uniaxial mechanical test data, while validated at the bulk scale by predicting tissue multiaxial mechanics for uniaxial tension, biaxial tension, and simple shear (13 cases). Structure-based model validation results were compared to experimental observations and homogeneous models. While homogeneous models only accurately predicted bulk tissue mechanics for one case, structure-based models accurately predicted bulk tissue mechanics for 12 of 13 cases, demonstrating accuracy and robustness. Additionally, six of eight structure-based model parameters were directly linked to tissue physical properties, further broadening its future applicability. In conclusion, the structure-based model provides a powerful multiscale modeling approach for simultaneously investigating the structure-function relationship at the sub-tissue and bulk tissue scale, which is important for studying multiscale tissue mechanics with degeneration, disease, or injury.