Enlargement of small, asymptomatic, unruptured intracranial aneurysms in patients with no history of subarachnoid hemorrhage: the different factors related to the growth of single and multiple aneurysms

Treatment of small intracranial aneurysms using the SMALLSS scoring system: a novel system for decision making

BACKGROUND

Treatment of unruptured intracranial aneurysms (UIA) less than 7 mm is controversial. We created a scoring system to guide decision making and validated the system utilizing over 700 cases treated with microsurgery or endovascular procedures.

METHODS

The scoring system SMALLSS included Size, (4-7 mm: 1 point, < 3.9 mm: 0 point), Multiple aneurysms (yes: 1, no: 0), Anatomic location (posterior: 1, anterior: 0), Lineage- family history of aneurysm (yes:1, no: 0), Lifetime risk (age < 65: 1, age > 65: 0), Smoking history (yes: 1, no: 0 ), Shape (irregular:1, smooth:0 ). Validation of this system was performed through retrospective review of prospectively maintained data for UIA patients treated between 2014 and 2021. We then performed an external validation of a cohort of 200 small aneurysms < 7 mm treated at a high volume cerebrovascular center.

RESULTS

A total of 1152 cases with unruptured intracranial aneurysms were treated over the study interval, of which 771 aneurysms (66.9%) were under 7 mm, with the majority (64.3%) having SMALLSS score more than 2. Serious neurologic complications occurred in 18 out of 771 aneurysms (2.33%) of which 4 were hemorrhagic and 14 were ischemic. The obliteration rate was 98% in microsurgery group, 89.7% in endovascular group. During this same interval, 1126 patients with aneurysms < 7 mm were evaluated and not offered treatment, with 74.7% SMALLSS scores of 2 and under. External validation data showed no significant deviations from our cohort with 150 out of 200 aneurysms (75%) with a SMALLSS score of 2 or greater.

CONCLUSION

The SMALLSS scoring system can be a good tool to guide treatment decision making for patients with small UIA. The risk of treatment did not increase with the projected increased risk of rupture and overall high obliteration rates were achieved with endovascular and surgical techniques.

Risk of unruptured aneurysms in subarachnoid hemorrhage patients with multiple intracranial aneurysms: a multicenter, longitudinal, comparative study from China

BACKGROUND

In aneurysmal subarachnoid hemorrhage patients with multiple intracranial aneurysms (aSAH-MIA patients), the risk of secondary unruptured intracranial aneurysms is inconsistent. This study aimed to explore the risk of unruptured aneurysms in Chinese aSAH-MIA patients.

METHODS

The medical records and angiographic images of aSAH-MIA patients from eight cerebrovascular centers in China were retrospectively reviewed and analyzed. Patients with a single unruptured intracranial aneurysm (UIA) and no prior aSAH were used as controls. Propensity score matching (PSM) was employed to balance the differences in age, gender, aneurysm size, aneurysm site, and follow-up duration between the two groups.

RESULTS

The study included 267 unruptured aneurysms from 204 aSAH-MIA patients and 769 single UIA. After PSM, 201 aneurysms were enrolled in the aSAH-MIA group and 201 aneurysms in the control group. The mean follow-up was 2.2 years. Thirty-four aneurysm instability events (28 growth and 6 rupture, 16.9%) occurred during follow-up in the aSAH-MIA group and 16 instability events (13 growth and 3 rupture, 8%) occurred in the control group. Risk factors for aneurysmal instability were aneurysm irregularity (OR 2.53; 95% CI 1.18 to 4.31), higher size ratio (OR 1.23; 95% CI 1.37 to 4.39), and middle cerebral artery location (OR 1.86; 95% CI 1.03 to 3.17). The risk of aneurysmal instability was substantially elevated in the aSAH-MIA group (HR 2.07; 95% CI 1.12 to 3.02).

CONCLUSIONS

Unruptured aneurysms in Chinese aSAH-MIA patients exhibited higher risks of growth and rupture than in patients with a single UIA. Middle cerebral artery location, higher size ratio and irregular shape were associated with higher risk of growth or rupture.

The clinical challenge of subarachnoid hemorrhage associated with multiple aneurysms when the bleeding source is not certainly identifiable

BACKGROUND

Multiple intracranial aneurysms (IAs) are encountered in 20-30% of the subarachnoid hemorrhages (SAH). Neuroimaging and clinical examination are usually sufficient to detect the bleeding source, but sometimes it can be misdiagnosed with catastrophic consequences.

METHODS

We reviewed our diagnostic work-up for all patients admitted from January 2016 to December 2020 for SAH with multiple IAs accounting for our rate of diagnostic failure. Then, we grouped the patients into 4 categories according to aneurysms topography and described our operative protocol in case of uncertain bleeding origin.

RESULTS

Sixty-two patients harboring 161 IAs were included. The bleeding source was identified in 56 patients (90.3%), who harbored other 81 bystander aneurysms. In 6 cases (9.7%) with a total of 24 aneurysms we failed the bleeding source identification. According to IAs topography, we grouped the IAs multiplicity in: 1) anterior plus posterior circulation IAs; 2) multiple posterior circulation IAs; 3) bilateral anterior circulation IAs; and 4) multiple ipsilateral anterior circulation IAs. In case of unidentified bleeding source, key-elements favoring the simultaneous multiple IAs treatment were their number, morphology, topography, clinicians' experience, and management modality as endovascular treatment allows a faster exclusion of multiple IAs distant one each other compared with surgery. MCA involvement represented the more frequent reason to prefer multiple clipping rather than multiple coiling.

CONCLUSIONS

In a small percentage of patients with SAH with multiple IAs, bleeding source identification can be difficult. Until the routinely availability of new tools such as vessel wall imaging or computational fluid dynamics, an experienced neurovascular team and strategies aiming to simultaneously exclude multiple IAs remain mandatory.

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.

Mathematical Analysis of the Effectiveness of Screening for Intracranial Aneurysms in First-Degree Relatives of Persons with Subarachnoid Hemorrhage

OBJECTIVE

Population screening for aneurysms in patients with risk factors and preventive surgical treatment are beneficial according to numerous studies. One of the most significant risk factors is heredity, namely, the presence of first-degree relatives (FDR) with aneurysmal subarachnoid hemorrhage (aSAH). Nevertheless, there are still no generally accepted approaches or evidence bases regarding the benefits of the aneurysm screening strategy.

METHODS

Mathematical modeling of the dynamics of aneurysm development in the population was carried out using an algorithm implementing a discrete Markov's chain. To implement the model, all probabilities of events and distributions are taken from available literature sources. Three-dimensional time of flight noncontrast magnetic resonance angiography was chosen as a screening method. Patients underwent preventive surgical treatment if an aneurysm was detected.

RESULTS

Screening and preventive treatment in the general population reduces the prevalence of aneurysms by 1.74% (3.44% in the FDR group) and the prevalence of aSAH by 14.36% (37.48% in the FDR group). Mortality due to aSAH was reduced by 14.44%. The number of disabilities also decreases. The occurrence of deep disability was reduced by 20.2% in the FDR group. Economic analysis of the part of the population consisting of FDRs showed annual savings of ies also decr CONCLUSIONS: The mathematical model demonstrated that screening and preventive treatment of cerebral aneurysms can reduce aSAH-associated morbidity and mortality. In the FDR group, there was decrease in the prevalence of aSAH and decrease in associated mortality. Screening for cerebral aneurysms is cost-effective.

A survey of the radiological follow-up of unruptured intracranial aneurysms in the United Kingdom

OBJECTIVE

Unruptured intracranial aneurysms (UIA) are common. For many the treatment risks outweigh their risk of subarachnoid haemorrhage and patients undergo surveillance imaging. There is little data to inform if and how to monitor UIAs resulting in widely varying practices. This study aimed to determine the current practice of unruptured UIA surveillance in the United Kingdom.

METHODS

A questionnaire was designed to address the themes of surveillance protocols for UIA including when surveillance is initiated, how frequently it is performed, and when it is terminated. Additionally, how aneurysm growth is managed and how clinically meaningful growth is defined were explored. The questionnaire was distributed to members of the British Neurovascular Group using probability-based cluster and non-probability purposive sampling methods.

RESULTS

Responses were received from 30 of the 30 (100.0%) adult neurosurgical units in the United Kingdom of which 27 (90.0%) routinely perform surveillance for aneurysm growth. Only four units had a unit policy. The mean patient age up to which a unit would initiate follow-up of a low-risk UIA was 65.4 ± 9.0 years. The time points at which imaging is performed varied widely. There was an even split between whether units use a fixed duration of follow-up or an age threshold for terminating surveillance. Forty percent of units will follow-up patients more than 5 years from diagnosis. The magnitude in the change in size that was felt to constitute growth ranged from 1 to 3mm. No units routinely used vessel wall imaging although 27 had access to 3T MRI capable of performing it.

CONCLUSIONS

There is marked heterogeneity in surveillance practices between units in the United Kingdom. This study will help units better understand their practice relative to their peers and provide a framework forplanning further research on aneurysm growth.

Reproducibility of the computational fluid dynamic analysis of a cerebral aneurysm monitored over a decade

Computational fluid dynamics (CFD) simulations are increasingly utilised to evaluate intracranial aneurysm (IA) haemodynamics to aid in the prediction of morphological changes and rupture risk. However, these models vary and differences in published results warrant the investigation of IA-CFD reproducibility. This study aims to explore sources of intra-team variability and determine its impact on the aneurysm morphology and CFD parameters. A team of four operators were given six sets of magnetic resonance angiography data spanning a decade from one patient with a middle cerebral aneurysm. All operators were given the same protocol and software for model reconstruction and numerical analysis. The morphology and haemodynamics of the operator models were then compared. The segmentation, smoothing factor, inlet and outflow branch lengths were found to cause intra-team variability. There was 80% reproducibility in the time-averaged wall shear stress distribution among operators with the major difference attributed to the level of smoothing. Based on these findings, it was concluded that the clinical applicability of CFD simulations may be feasible if a standardised segmentation protocol is developed. Moreover, when analysing the aneurysm shape change over a decade, it was noted that the co-existence of positive and negative values of the wall shear stress divergence (WSSD) contributed to the growth of a daughter sac.

Image-derived Metrics Quantifying Hemodynamic Instability Predicted Growth of Unruptured Intracranial Aneurysms

Background

While image-derived predictors of intracranial aneurysm (IA) rupture have been well-explored, current understanding of IA growth is limited. Pulsatility index (PI) and wall shear stress pulsatility index (WSSPI) are important metrics measuring temporal hemodynamic instability. However, they have not been investigated in IA growth research. The present study seeks to verify reliable predictors of IA growth with comparative analyses of several important morphological and hemodynamic metrics between stable and growing cases among a group of unruptured IAs.

Methods

Using 3D images, vascular models of 16 stable and 20 growing cases were constructed and verified using Geodesic techniques. With an overall mean follow-up period of 25 months, cases exhibiting a 10% or higher increase in diameter were considered growing. Patient-specific, pulsatile simulations were performed, and hemodynamic calculations were computed at 5 important regions of each aneurysm (inflow artery, aneurysm neck, body, dome, and outflow artery). Index values were compared between growing and stable IAs using ANCOVA controlling for aneurysm diameter. Stepwise multiple logistic regression and ROC analyses were conducted to investigate predictive models of IA growth.

Results

Compared to stable IAs, growing IAs exhibited significantly higher intrasaccular PI, intrasaccular WSSPI, intrasaccular spatial flow rate deviation, and intrasaccular spatial wall shear stress (WSS) deviation. Stepwise logistic regression analysis revealed a significant predictive model involving PI at aneurysm body, WSSPI at inflow artery, and WSSPI at aneurysm body.

Conclusions

Our results showed that high degree of hemodynamic variations within IAs is linked to growth, even after controlling for morphological parameters. Further, evaluation of PI in conjunction with WSSPI yielded a highly accurate predictive model of IA growth. Upon validation in future cohorts, these metrics may aid in early identification of IA growth and current understanding of IA remodeling mechanism.

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.

Development and External Validation of a Dynamic Nomogram With Potential for Risk Assessment of Ruptured Multiple Intracranial Aneurysms

Background and Purpose

About 20.1% of intracranial aneurysms (IAs) carriers are multiple intracranial aneurysms (MIAs) patients with higher rupture risk and worse prognosis. A prediction model may bring some potential benefits. This study attempted to develop and externally validate a dynamic nomogram to assess the rupture risk of each IA among patients with MIA.

Method

We retrospectively analyzed the data of 262 patients with 611 IAs admitted to the Hunan Provincial People's Hospital between November 2015 and November 2021. Multivariable logistic regression (MLR) was applied to select the risk factors and derive a nomogram model for the assessment of IA rupture risk in MIA patients. To externally validate the nomogram, data of 35 patients with 78 IAs were collected from another independent center between December 2009 and May 2021. The performance of the nomogram was assessed in terms of discrimination, calibration, and clinical utility.

Result

Size, location, irregular shape, diabetes history, and neck width were independently associated with IA rupture. The nomogram showed a good discriminative ability for ruptured and unruptured IAs in the derivation cohort (AUC = 0.81; 95% CI, 0.774–0.847) and was successfully generalized in the external validation cohort (AUC = 0.744; 95% CI, 0.627–0.862). The nomogram was calibrated well, and the decision curve analysis showed that it would generate more net benefit in identifying IA rupture than the “treat all” or “treat none” strategies at the threshold probabilities ranging from 10 to 60% both in the derivation and external validation set. The web-based dynamic nomogram calculator was accessible on https://wfs666.shinyapps.io/onlinecalculator/.

Conclusion

External validation has shown that the model was the potential to assist clinical identification of dangerous aneurysms after longitudinal data evaluation. Size, neck width, and location are the primary risk factors for ruptured IAs.

Analysis of Factors Related to Growth and Growth Patterns of Unruptured Intracranial Aneurysms

Objective

Methods

Results

Conclusion

Risk factors for the progression of unruptured intracranial aneurysms in patients followed by CT/MR angiography

Background

The progression of an unruptured intracranial aneurysm (UIA) is associated with a higher rupture risk. The aim of this study was to identify the risk factors for the progression of UIAs among Chinese adults and compare them with the ELAPSS (Earlier subarachnoid hemorrhage, IA Location, Age, Population, IA Size and Shape) score.

Methods

Four hundred thirty-eight consecutive patients with 491 UIAs were followed and reviewed retrospectively from August 2011 to November 2019. Follow-up images of the UIAs were used to determine changes in IA size and shape. Patients and IAs were divided into non-progression and progression groups. In addition to the clinical characteristics of the patients, the features of the IAs (e.g., size and shape) were evaluated by computed tomography angiography (CTA) or magnetic resonance angiography (MRA). Independent risk factors for UIA progression were studied using multiple Cox proportional hazards regression analysis. In addition, the diagnostic value of the ELAPSS score for the prediction of UIA progression was calculated.

Results

Seventy-two IAs in 68 patients progressed during a mean follow-up time of 24.2±19.68 months. IAs located at the bifurcation [odds ratio (OR) 2.600], with an irregular shape (OR 2.981) or having a high aspect ratio (AR, OR 2.430) were correlated with progression. Based on these three factors, the threshold value of our predictive score was 0.5, and the area under the curve (AUC), sensitivity and specificity were 0.756, 93.1% and 40.6%, respectively, while the AUC, sensitivity and specificity of the ELAPSS score were 0.711, 55.6%, and 75.2%, respectively.

Conclusions

IAs located at the bifurcation, with an irregular shape and with an elevated AR are risk factors for UIA progression in the Chinese population. Our predictive score is of great value in predicting the risk of UIA progression.

A Volumetric Metric for Monitoring Intracranial Aneurysms: Repeatability and Growth Criteria in a Longitudinal MR Imaging Study

BACKGROUND AND PURPOSE

The reliability of contrast-enhanced MRA in monitoring serial volumetric changes of unruptured intracranial aneurysms has not been established. We aimed to determine the coefficient of variance of contrast-enhanced MRA in measuring aneurysm volumes, thus establishing criteria for aneurysm growth and permitting identification of variables predictive of growth.

MATERIALS AND METHODS

Aneurysm volumes were measured from serial contrast-enhanced MRA studies of patients with untreated intracranial aneurysms who underwent >2 sequential MR imaging evaluations. After coregistering all sequential studies in 3D space for each aneurysm and signal intensity normalization, aneurysm volume was determined across all time points. A linear mixed effects model was built to estimate the coefficient of variance of the measurement as well as to determine predictive variables. Growth was defined as relative growth exceeding 2 times the measurement coefficient of variance (sudden growth, as 4 times the coefficient of variance).

RESULTS

A total of 95 patients with 112 aneurysms were included (5.9 scans during 4.0 years on average, 616 scan measurements in total). The coefficient of variance was 5.5% of the aneurysm volume, and the relative growth rate was dependent on the location: anterior cerebral artery, 4.52% per year; vertebral artery, 2.46% per year; middle cerebral artery, 2.74% per year; basilar artery, 2.36% per year; internal carotid artery, 1.14% per year. Thirty-six of 112 (32%) aneurysms were characterized as growing, and 11/36 of them had an episode of sudden growth.

CONCLUSIONS

Volume measurement of unruptured intracranial aneurysms by contrast-enhanced MRA seems a reliable metric for tracking the growth trajectory of aneurysms. Furthermore, the aneurysm growth rate differs among different locations.

Atorvastatin and growth, rupture of small unruptured intracranial aneurysm: results of a prospective cohort study

Background and aims:

The role of statins in unruptured intracranial aneurysm (UIA) growth and rupture remains ambiguous. This study sought to determine whether atorvastatin is associated with aneurysm growth and rupture in patients harboring UIA <7 mm.

Methods:

This prospective, multicenter cohort study consecutively enrolled patients with concurrent UIA <7 mm and ischemic cerebrovascular disease from four hospitals between 2016 and 2019. Baseline and follow-up patient information was recorded. Because of the strong anti-inflammatory effect of aspirin, patients using aspirin were excluded. Patients taking atorvastatin 20 mg daily were atorvastatin users. The primary and exploratory endpoints were aneurysm rupture and growth, respectively.

Results:

Among the 1087 enrolled patients, 489 (45.0%) took atorvastatin, and 598 (55%) took no atorvastatin. After a mean follow-up duration of 33.0 ± 12.5 months, six (1.2%) and five (0.8%) aneurysms ruptured in atorvastatin and non-atorvastatin groups, respectively. In the adjusted multivariate Cox analysis, UIA sized 5 to <7 mm, current smoker, and uncontrolled hypertension were associated with aneurysm rupture, whereas atorvastatin [adjusted hazard ratio (HR) 1.495, 95% confidence interval (CI) 0.417–5.356, p = 0.537] was not. Of 159 patients who had follow-up imaging, 34 (21.4%) took atorvastatin and 125 (78.6%) took no atorvastatin. Aneurysm growth occurred in five (14.7%) and 21 (16.8%) patients in atorvastatin and non-atorvastatin groups (mean follow-up: 20.2 ± 12.9 months), respectively. In the adjusted multivariate Cox analysis, UIAs sized 5 to <7 mm and uncontrolled hypertension were associated with a high growth rate; atorvastatin (adjusted HR 0.151, 95% CI 0.031–0.729, p = 0.019) was associated with a reduced growth rate.

Conclusions:

We conclude atorvastatin use is associated with a reduced risk of UIA growth, whereas atorvastatin is not associated with UIA rupture.

Radiological surveillance of small unruptured intracranial aneurysms: a systematic review, meta-analysis, and meta-regression of 8428 aneurysms

With the widespread use of imaging techniques, the possibility that an asymptomatic unruptured intracranial aneurysm (UIA) is detected has increased significantly. There is no established consensus regarding follow-up, duration, and frequency of such imaging surveillance. The objectives of this study include assessing the growth rate and rupture risk of small (less than 7mm) UIAs, identifying associated risk factors and providing an aneurysm surveillance protocol in appropriately selected patients. Systematic searches of Medline, Embase, and Cochrane Central were undertaken from database inception to March 2020 for published studies reporting the growth and rupture risks of small UIAs. Twenty-one studies reporting 8428 small UIAs were included in our meta-analysis. The pooled mean age was 61 years (95% CI: 55-67). The mean follow-up period for growth and rupture ranged from 11 to 108 months, with the pooled mean follow-up period across 14 studies being 42 months (95% CI: 33-51). Pooled overall growth rate was 6.0% (95% CI: 3.8-8.7). Pooled growth rates for aneurysms < 5mm and < 3 mm were 5.2% (95% CI: 3.0-7.9) and 0.8% (95% CI: 0.0-6.1), respectively. Pooled overall rupture rate was 0.4% (95% CI: 0.2-0.7). From the meta-regression analysis, having multiple aneurysms, smoking, hypertension, and personal history of SAH did not significantly predict growth, and a personal history of SAH, smoking, hypertension, and multiple aneurysms were not statistically significant predictors of rupture. Our findings suggest that small UIAs have low growth and rupture rates and very small UIAs have little or no risk for rupture. In the setting of incidental small UIAs, patients with multiple and/or posterior circulation aneurysms require more regular radiological monitoring.

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.

Aspirin and Growth of Small Unruptured Intracranial Aneurysm

Background and Purpose:

The role of aspirin in unruptured intracranial aneurysm (UIA) growth remains largely unknown. We aim to identify whether aspirin is associated with a lower rate of UIA growth in patients with UIA <7 mm.

Methods:

This prospective cohort study consecutively enrolled patients with UIAs <7 mm with ischemic cerebrovascular disease between January 2016 and December 2019. Baseline and follow-up patient information, including the use of aspirin and blood pressure level, were recorded. Patients were considered aspirin users if they took aspirin, including standard- and low-dose aspirin, ≥3× per week. The primary end point was aneurysm growth in any direction or an indisputable change in aneurysm shape.

Results:

Among the 315 enrolled patients, 272 patients (86.3%) underwent imaging examinations during follow-up (mean follow-up time, 19.6±12.7 months). A total of 113 patients were continuously treated with aspirin. UIA growth occurred in 31 (11.4%) patients. In the multivariate Cox analysis, specific aneurysm locations (anterior communicating artery, posterior communicating artery, or middle cerebral artery; hazard ratio, 2.89 [95% CI, 1.22–6.88]; P =0.016) and a UIA size of 5 to <7 mm (hazard ratio, 7.61 [95% CI, 3.02–19.22]; P <0.001) were associated with a high risk of UIA growth, whereas aspirin and well-controlled blood pressure were associated with a low risk of UIA growth (hazard ratio, 0.29 [95% CI, 0.11–0.77]; P =0.013 and hazard ratio, 0.25 [95% CI, 0.10–0.66]; P =0.005, respectively). The cumulative annual growth rates were as high as 40.0 and 53.3 per 100 person-years in the high-risk patients (>1 risk factor) with and without aspirin, respectively.

Conclusions:

Aspirin therapy and well-controlled blood pressure are associated with a low risk of UIA growth; the incidence of UIA growth in high-risk patients in the first year is high, warranting intensive surveillance in this patient group.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02846259.

Unruptured intracranial aneurysm growth trajectory: occurrence and rate of enlargement in 520 longitudinally followed cases

OBJECTIVE

As imaging technology has improved, more unruptured intracranial aneurysms (UIAs) are detected incidentally. However, there is limited information regarding how UIAs change over time to provide stratified, patient-specific UIA follow-up management. The authors sought to enrich understanding of the natural history of UIAs and identify basic UIA growth trajectories, that is, the speed at which various UIAs increase in size.

METHODS

From January 2005 to December 2015, 382 patients diagnosed with UIAs (n = 520) were followed up at UCLA Medical Center through serial imaging. UIA characteristics and patient-specific variables were studied to identify risk factors associated with aneurysm growth and create a predicted aneurysm trajectory (PAT) model to differentiate aneurysm growth behavior.

RESULTS

The PAT model indicated that smoking and hypothyroidism had a large effect on the growth rate of large UIAs (≥ 7 mm), while UIAs < 7 mm were less influenced by smoking and hypothyroidism. Analysis of risk factors related to growth showed that initial size and multiplicity were significant factors related to aneurysm growth and were consistent across different definitions of growth. A 1.09-fold increase in risk of growth was found for every 1-mm increase in initial size (95% CI 1.04-1.15; p = 0.001). Aneurysms in patients with multiple aneurysms were 2.43-fold more likely to grow than those in patients with single aneurysms (95% CI 1.36-4.35; p = 0.003). The growth rate (speed) for large UIAs (≥ 7 mm; 0.085 mm/month) was significantly faster than that for UIAs < 3 mm (0.030 mm/month) and for males than for females (0.089 and 0.045 mm/month, respectively; p = 0.048).

CONCLUSIONS

Analyzing longitudinal UIA data as continuous data points can be useful to study the risk of growth and predict the aneurysm growth trajectory. Individual patient characteristics (demographics, behavior, medical history) may have a significant effect on the speed of UIA growth, and predictive models such as PAT may help optimize follow-up frequency for UIA management.

Risk Factors for Asymptomatic Intracranial Small Aneurysm Rupture Determined by Electrocardiographic-Gated 4D Computed Tomographic (CT) Angiography

Background

To study the risk predictors of intracranial asymptomatic small aneurysm rupture by electrocardiographic (ECG)-gated 4D-CT angiography (4D-CTA).

Material/Methods

A total of 168 patients with intracranial aneurysms <7 mm who underwent 4D-CTA examinations were retrospectively analyzed and divided into a ruptured group and an unruptured group. The original scanning data of all cases were reconstructed to obtain 20 groups of data in 5% time intervals in the cardiac cycle. After processing with 3D workstation software, 20 sets of images and dynamic images were achieved. The morphological characteristics and clinical features of the 2 groups of aneurysms were analyzed through univariate analysis, then logistic regression analysis was performed for the meaningful indicators. Finally, the optimum diagnostic cut-off point was calculated by ROC curve analysis.

Results

Univariate analysis showed that sex, smoking history, vascular bifurcation point, pulsation point appearance, aneurysm height, aspect ratio (AR), and size ratio (SR) were significantly different (P<0.05) between the ruptured group and unruptured group. Multivariate regression analysis indicated that the pulsation points (OR=8.188, 95% CI: 3.984–17.198) and high SR values (OR=5.325, 95% CI: 1.503–18.867) were independent predictors of asymptomatic small aneurysm rupture. When the SR value was higher than 1.65, the area below the ROC curve was 0.723, the diagnostic sensitivity was 75%, and the specificity was 80%.

Conclusions

The occurrence of pulsation points and SR values >1.65 were independent predictors for the rupture of asymptomatic small intracranial aneurysms <7 mm in diameter.

Cavernous sinus aneurysms: risk of growth over time and risk factors

OBJECTIVE

Cavernous internal carotid artery (ICA) aneurysms are frequently diagnosed incidentally and the benign natural history of these lesions is well known, but there is limited information assessing the risk of growth in untreated patients. The authors sought to assess and analyze risk factors in patients with cavernous ICA aneurysms and compare them to those of patients with intracranial berry aneurysms in other locations.

METHODS

Data from consecutive patients who were diagnosed with a cavernous ICA aneurysm were retrospectively reviewed. The authors evaluated patients for the incidence of cavernous ICA aneurysm growth and rupture. In addition, the authors analyzed risk factors for cavernous ICA aneurysm growth and compared them to risk factors in a population of patients diagnosed with intracranial berry aneurysms in locations other than the cavernous ICA during the same period.

RESULTS

In 194 patients with 208 cavernous ICA aneurysms, the authors found a high risk of aneurysm growth (19.2% per patient-year) in patients with large/giant aneurysms. Size was significantly associated with higher risk of growth. Compared to patients with intracranial berry aneurysms in other locations, patients with cavernous ICA aneurysms were significantly more likely to be female and have a lower incidence of hypertension.

CONCLUSIONS

Aneurysms of the cavernous ICA are benign lesions with a negligible risk of rupture but a definite risk of growth. Aneurysm size was found to be associated with aneurysm growth, which can be associated with new onset of symptoms. Serial follow-up imaging of a cavernous ICA aneurysm might be indicated to monitor for asymptomatic growth, especially in patients with larger lesions.

A systematic review and meta-analysis of risk factors for unruptured intracranial aneurysm growth

BACKGROUND

Many risk factors are associated with the growth of unruptured intracranial aneurysm; however, the effects of these risk factors on intracranial aneurysm growth remain poorly understood. Here, we performed a meta-analysis to evaluate the effects of these risk factors on intracranial aneurysm growth, incorporating different data types to provide comprehensive estimates of individual effects.

METHODS

We searched the Cochrane Library, PubMed, Embase, and Web of Science for cohort studies analyzing risk factors for aneurysm growth prior to January 10, 2019. The hazard ratio (HR) and odds ratio (OR) with its 95% confidence interval (CI) were calculated to assess the effect of individual risk factors on intracranial aneurysm growth. Both univariate analysis (UVA) and multivariate analysis (MVA) were performed. Two reviewers independently assessed the quality of the trials and the associated data. All statistical analyses were performed using standard statistical procedures provided in Review Manager 5.2.

RESULTS

We included 23 studies (N = 7208 participants) in this meta-analysis. A total of 944 patients (13.1%) experienced intracranial aneurysm growth during their follow-up times. Aneurysm size and smoking may have significant effects on the growth of intracranial aneurysm, with pooled ORs of 2.73 (95% CI 2.21-3.36; P < 0.00001) and 1.45 (95% CI 1.07-1.98; P = 0.02) respectively. However, our results indicated that subarachnoid hemorrhage (SAH) had a negative effect on the growth of intracranial aneurysm (OR 0.64; 95% CI 0.48-0.86; P = 0.003). Other risk factors such as irregular shape of intracranial aneurysm, female sex, and multiple aneurysms were inconsistent across studies due to differences in data types and effect estimates.

CONCLUSIONS

Our meta-analysis identified aneurysm size and smoking as independent risk factors for the growth of intracranial aneurysm, while prior SAH had a negative effect on the growth of intracranial aneurysm. The roles of other risk factors for intracranial aneurysm growth were inconsistent, with further research necessary to assess fully the roles of these factors in disease outcomes.

Small Aneurysms Should Be Clipped?

Background:

Cerebral aneurysm prevalence may vary from 0.4% to 10%. The decision to treat or not incidental aneurysms remains controversial, especially when the lesions are small (<5 mm). Many recent publications are demonstrating that these lesions often bleed.

Methods:

We reviewed admitted patients with angiographic studies submitted to intracranial aneurysm surgical treatment from April 2012 to July 2013 in the Neurosurgery Department of São Paulo Medical School University (15 months), to define the rate and risk of bleeding. In addition, we proceeded literature review with collected 357 papers (past 5 years) which were selected 50 that were focused on our research. Clinical patients’ status at the time of discharge was evaluated with the modified Rankin scale.

Results:

A series of 118 cases of surgically clipped aneurysms was analyzed: 73.7% woman; Ruptured (61 cases, 51%); middle cerebral artery (51 cases, 43%) was the more common aneurysm. Small size (<5 mm) was 25 cases (21%); that 2 died (16%), 3 (25%) with severe disability,restricted to bed and dependent on nursing care; blood pressure was the main risk factors (56%); and an aneurysm <2 mm (100%) was ruptured.

Conclusion:

The number of small aneurysms in our series was significant (25 cases, 21%), and its rate of bleeding was high (25 cases, 48%), resulting in death and disability in a significant number of cases. Our tendency is for surgical treatment when it is associated with risk factors.

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

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

Nonsphericity Index and Size Ratio Identify Morphologic Differences between Growing and Stable Aneurysms in a Longitudinal Study of 93 Cases

BACKGROUND AND PURPOSE

Recent studies have strongly associated intracranial aneurysm growth with increased risk of rupture. Identifying aneurysms that are likely to grow would be beneficial to plan more effective monitoring and intervention strategies. Our hypothesis is that for unruptured intracranial aneurysms of similar size, morphologic characteristics differ between aneurysms that continue to grow and those that do not.

MATERIALS AND METHODS

From aneurysms in our medical center with follow-up imaging dates in 2015, ninety-three intracranial aneurysms (23 growing, 70 stable) were selected. All CTA images for the aneurysm diagnosis and follow-up were collected, a total of 348 3D imaging studies. Aneurysm 3D geometry for each imaging study was reconstructed, and morphologic characteristics, including volume, surface area, nonsphericity index, aspect ratio, and size ratio were calculated.

RESULTS

Morphologic characteristics were found to differ between growing and stable groups. For aneurysms of <3 mm, nonsphericity index (P < .001); 3-5 mm, nonsphericity index (P < .001); 5-7 mm, size ratio (P = .003); >7 mm, volume (P < .001); surface area (P < .001); and nonsphericity index (P = .002) were significant. Within the anterior communicating artery, the nonsphericity index (P = .008) and, within the posterior communicating artery, size ratio (P = .004) were significant. The nonsphericity index receiver operating characteristic area under the curve was 0.721 for discriminating growing and stable cases on the basis of initial images.

CONCLUSIONS

Among aneurysms with similar sizes, morphologic characteristics appear to differ between those that are growing and those that are stable. The nonsphericity index, in particular, was found to be higher among growing aneurysms. The size ratio was found to be the second most significant parameter associated with growth.

Small Aneurysms Account for the Majority and Increasing Percentage of Aneurysmal Subarachnoid Hemorrhage: A 25-Year, Single Institution Study

BACKGROUND

Prospective studies of unruptured aneurysms have shown very low rates of rupture for small aneurysms (&lt;10 mm) and suggested that the risk of treatment outweighs benefit. However, common clinical practice shows that patients with aneurysmal subarachnoid hemorrhage (aSAH) frequently have small aneurysms.

OBJECTIVE

To investigate trends in size and location of ruptured aneurysms over a 25-yr period.

METHODS

A prospective, Institutional Review Board-approved database of all patients presenting to our institution with aSAH from 1991 to 2016 was analyzed. Cerebral angiography identified the source of hemorrhage. Patients with nonaneurysmal etiologies were excluded.

RESULTS

Complete data were available for 1306/1562 patients (84%) with aSAH from 1991 to 2016. The average age was 53 yr and 72% of patients were female. The average size of ruptured aneurysms over 25 yr was 8.0 mm. The average size of ruptured aneurysms decreased steadily with each 5-yr interval from 10.1 mm (1991-1996) to 6.6 mm (2012-2016; P &lt; .001). Overall, very small aneurysms (&lt;5 mm) were responsible for aSAH in 41% of patients. The percentage of very small ruptured aneurysms rose from 29% during the initial 5-yr period (1991-1996) to 50% in the most recent period. Likewise, the percentage of ruptured aneurysms that were 5 to 9 mm rose from 26% to 34% (P &lt; .001). In the past 5 yr, aneurysms &lt;10 mm accounted for 84% of aSAH. Vessel of origin (P = .097) and aneurysm location (P = .322) did not vary with time.

CONCLUSION

Ruptured small and very small aneurysms represent a majority and increasing share of aSAH. Identification and prophylactic treatment of these aneurysms remains an important clinical role for cerebrovascular neurosurgery.

Growth and Rupture Risk of Small Unruptured Intracranial Aneurysms: A Systematic Review

BACKGROUND

Small unruptured intracranial aneurysms (UIAs) are increasingly diagnosed. Management depends on growth and rupture risks, which may vary by aneurysm size.

PURPOSE

To summarize evidence about the growth and rupture risk of UIAs 7 mm and smaller and to explore differences in growth and rupture risks of very small (≤3 mm) and small (≤5 mm) aneurysms.

DATA SOURCES

MEDLINE, EMBASE, Scopus, and the Cochrane Library from inception to 2017 (with no language restrictions).

STUDY SELECTION

Published case series and observational studies that reported natural history data on UIAs 7 mm and smaller.

DATA EXTRACTION

2 reviewers abstracted study information, evaluated study quality, and graded strength of evidence.

DATA SYNTHESIS

Of 26 studies, 5, 10, and 8 described the growth rate of aneurysms 3 mm and smaller, 5 mm and smaller, and 7 mm and smaller, respectively, whereas rupture rates were reported in 7, 11, and 13 studies for aneurysms 3 mm and smaller, 5 mm and smaller, and 7 mm and smaller, respectively. The annualized growth rate was less than 3% in all but 1 study for all 3 size categories. The annualized rupture rate was 0%, less than 0.5%, and less than 1% for the 3 size categories, respectively. Strength of evidence was very low quality for growth rates and low quality for rupture rates.

LIMITATION

Heterogeneous definitions of growth; heterogeneous and selective treatment and follow-up methods, particularly in high-risk patients.

CONCLUSION

Poor-quality evidence suggests that small UIAs have low growth and rupture rates and very small UIAs have little or no risk for rupture.

PRIMARY FUNDING SOURCE

None.

Posterior communicating artery aneurysms demonstrate faster interval growth than other growing aneurysms

Background Posterior communicating artery aneurysms are often associated with a high rupture risk. This study compares the differences in the rate of growth and morphological characteristics between growing posterior communicating artery aneurysms and other types of growing aneurysms. Materials and methods Thirteen patients with growing internal carotid artery aneurysms were scanned using Siemens 64 slice computed tomography scanners. Three patients had ophthalmic aneurysms, three had superior hypophyseal aneurysms and seven had posterior communicating artery aneurysms. Each aneurysm case had three distinct time points, with an average separation time of 1.3 ± 0.6 years. Annual aneurysm dimensional growth, annual volume growth, annual increase in surface area, size ratio, aspect ratio, and non-sphericity index were analysed. Results Posterior communicating artery aneurysms demonstrated significantly higher annual increases in dimensional growth, volume and surface area when compared to other internal carotid artery aneurysms. Posterior communicating artery aneurysms also demonstrated a significantly higher increase in aspect ratio, size ratio and lower non-sphericity index. Discussion Posterior communicating artery aneurysms had significantly greater growth per year when compared to other types of internal carotid artery aneurysms, and had different morphological characteristics.

Accuracy in Identifying the Source of Subarachnoid Hemorrhage in the Setting of Multiple Intracranial Aneurysms

BACKGROUND

Subarachnoid hemorrhage cases with multiple cerebral aneurysms frequently demonstrate a hemorrhage pattern that does not definitively delineate the source aneurysm. In these cases, rupture site is ascertained from angiographic features of the aneurysm such as size, morphology, and location.

OBJECTIVE

To examine the frequency with which such features lead to misidentification of the ruptured aneurysm.

METHODS : Records of patients who underwent surgical clipping of a ruptured aneurysm at our institution between 2004 and 2014 and had multiple aneurysms were retrospectively reviewed. A blinded neuroendovascular surgeon provided the rupture source based on the initial head computed tomography scans and digital subtraction angiography images. Operative reports were then assessed to confirm or refute the imaging-based determination of the rupture source.

RESULTS

One hundred fifty-one patients had multiple aneurysms. Seventy-one patients had definitive hemorrhage patterns on initial computed tomography scans and 80 patients had nondefinitive hemorrhage patterns. Thirteen (16.2%) of the cases with nondefinitive hemorrhage patterns had discordance between the imaging-based determination of the rupture source and intraoperative findings of the true ruptured aneurysm, yielding an imperfect positive predictive value of 83.8%. Of all multiple aneurysm cases with subarachnoid hemorrhage treated by surgical or endovascular means at our institution, 4.3% (13 of 303) were misidentified.

CONCLUSION

Morphological features cannot reliably be used to determine rupture site in cases with nondefinitive subarachnoid hemorrhage patterns. Microsurgical clipping, confirming obliteration of the ruptured lesion, may be preferentially indicated in these patients unless, alternatively, all lesions can be contemporaneously and safely treated with endovascular embolization.

Bifurcation Location Is Significantly Associated with Rupture of Small Intracranial Aneurysms (<5 mm)

BACKGROUND AND OBJECTIVE

Patients with small (<5 mm) unruptured intracranial aneurysms (UIAs) are at risk of subarachnoid hemorrhage, but risk assessment of these patients remains controversial in daily clinical practice. We aimed to identify the risk factors of aneurysmal rupture in these patients.

METHODS

We retrospectively analyzed consecutive patients with small UIAs who were admitted to our center between February 2009 and December 2014. The enrolled patients were divided into ruptured and unruptured groups. The risk factors for aneurysmal rupture were determined using multivariate logistic regression analysis.

RESULTS

A total of 548 patients with 618 small intracranial aneurysms (267 ruptured and 351 unruptured) were included. Univariate analysis showed that rupture of small aneurysms was related to sex, age, smoking, hypertension, aspect ratio, size ratio, irregular shape, aneurysm width, height, and neck diameter, and location at bifurcation or posterior circulation. Multivariate logistic regression showed that rupture was associated with bifurcation location (odds ratio [OR], 5.409; 95% confidence interval [CI], 3.656-8.001; P < 0.001), size ratio (OR, 3.092; 95% CI, 2.002-4.774; P < 0.001), location (OR, 2.624; 95% CI, 1.428-4.824; P = 0.002), hypertension (OR, 1.698; 95% CI, 1.1140-2.527; P = 0.009), and age at diagnosis of UIA (OR, 1.826; 95% CI, 1.225-2.723; P = 0.003).

CONCLUSIONS

This study showed that 70.4% of small ruptured intracranial aneurysms (<5 mm) were located at parent artery bifurcations and that bifurcation location was a significant independent factor for the risk of rupture of small UIAs (<5 mm). Prophylactic treatment should be recommended for small UIAs in this location.

Patient and aneurysm characteristics associated with rupture risk of multiple intracranial aneurysms in the anterior circulation system

BACKGROUND

Multiple intracranial aneurysms (MIAs) are associated with poorer outcomes after rupture than are single intracranial aneurysms (SIAs). Although the risk factors for intracranial aneurysm rupture have been widely investigated, few studies have focused on MIAs. Thus, the present study aimed to determine whether there are differences in the patient and aneurysm characteristics between those with ruptured and unruptured anterior circulation MIAs (AC-MIAs).

METHOD

The present study included 97 patients with AC-MIAs (58 ruptured, 39 unruptured). Data regarding patient characteristics, aneurysm location, mirror aneurysms (MirAns), and bleb formations were collected from medical records and angiography images. Three-dimensional (3D) geometries generated with a 3D Slicer were evaluated to determine the range of morphological parameters. A univariate analysis was conducted to identify significant differences between the groups and receiver-operating characteristic (ROC) analyses were performed for each morphological parameter.

RESULTS

There are significantly fewer patients younger than 40 years of age in the ruptured group (P = 0.04); although the groups did not significantly differ with regard to smoking and hypertension, the ruptured group included significantly more current smokers who smoked more than 20 cigarettes per day (P = 0.025) and significantly more patients with a history of hypertension but an irregular use of anti-hypertensive medications (P = 0.043). Ruptured AC-MIAs were more likely to be located in the internal carotid artery (ICA) communicating artery (ICA C7) and anterior communicating artery (AComA; P = 0.000), to have formed a pair of MirAns (P = 0.001), and to have a bleb formation (P = 0.000). In terms of morphological parameters, the two groups differed significantly regarding aneurysm size (P = 0.000), neck width (P = 0.016), bottleneck factor (BNF; P = 0.000), height/width ratio (H/W; P = 0.031), aspect ratio (AR; P = 0.000) and size ratio (SR; P = 0.000). Additionally, the ROC analyses revealed that the optimal threshold size for rupture was 4.00 mm and that the SR had the highest area under the curve (AUC) value (0.826).

CONCLUSIONS

The present study found that current smokers who smoked more than 20 cigarettes per day and those with hypertension but an irregular use of anti-hypertensive medications were more likely to suffer from rupture. Aneurysm location and bleb formation were closely related to the rupture of AC-MIAs, and SR was a better predictor of AC-MIAs rupture status than size, neck width, BNF, H/W and AR. These findings should be verified by future prospective follow-up studies of AC-MIAs.

Aneurysm growth and de novo aneurysms during aneurysm surveillance

OBJECTIVE Many low-risk unruptured intracranial aneurysms (UIAs) are followed for growth with surveillance imaging. Growth of UIAs likely increases the risk of rupture. The incidence and risk factors of UIA growth or de novo aneurysm formation require further research. The authors retrospectively identify risk factors and annual risk for UIA growth or de novo aneurysm formation in an aneurysm surveillance protocol. METHODS Over an 11.5-year period, the authors recommended surveillance imaging to 192 patients with 234 UIAs. The incidence of UIA growth and de novo aneurysm formation was assessed. With logistic regression, risk factors for UIA growth or de novo aneurysm formation and patient compliance with the surveillance protocol was assessed. RESULTS During 621 patient-years of follow-up, the incidence of aneurysm growth or de novo aneurysm formation was 5.0%/patient-year. At the 6-month examination, 5.2% of patients had aneurysm growth and 4.3% of aneurysms had grown. Four de novo aneurysms formed (0.64%/patient-year). Over 793 aneurysm-years of follow-up, the annual risk of aneurysm growth was 3.7%. Only initial aneurysm size predicted aneurysm growth (UIA < 5 mm = 1.6% vs UIA ≥ 5 mm = 8.7%, p = 0.002). Patients with growing UIAs were more likely to also have de novo aneurysms (p = 0.01). Patient compliance with this protocol was 65%, with younger age predictive of better compliance (p = 0.01). CONCLUSIONS Observation of low-risk UIAs with surveillance imaging can be implemented safely with good adherence. Aneurysm size is the only predictor of future growth. More frequent (semiannual) surveillance imaging for newly diagnosed UIAs and UIAs ≥ 5 mm is warranted.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

Risk Factors for Growth of Intracranial Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Understanding risk factors for intracranial aneurysm growth is important for patient management. We performed a meta-analysis examining risk factors for intracranial aneurysm growth in longitudinal studies and examined the association between aneurysm growth and rupture.

MATERIALS AND METHODS

We searched the literature for longitudinal studies of patients with unruptured aneurysms. We examined the associations of demographics, multiple aneurysms, prior subarachnoid hemorrhage, family history of aneurysm or subarachnoid hemorrhage, smoking, and hypertension; and aneurysm shape, size, and location with aneurysm growth. We studied the association between aneurysm growth and rupture. A meta-analysis was performed by using a random-effects model by using summary statistics from included studies.

RESULTS

Twenty-one studies including 3954 patients with 4990 aneurysms with 13,294 aneurysm-years of follow-up were included. The overall proportion of growing aneurysms was 3.0% per aneurysm-year (95% CI, 2.0%-4.0%). Patient risk factors for growth included age older than 50 years (3.8% per year versus 0.9% per year, P < .01), female sex (3.2% per year versus 1.3% per year, P < .01), and smoking history (5.5% per year versus 3.5% per year, P < .01). Characteristics associated with higher growth rates included cavernous carotid artery location (14.4% per year), nonsaccular shape (14.7% per year versus 5.2% per year for saccular, P < .01), and aneurysm size (P < .01). Aneurysm growth was associated with a rupture rate of 3.1% per year compared with 0.1% per year for stable aneurysms (P < .01).

CONCLUSIONS

Observational evidence provided multiple clinical and anatomic risk factors for aneurysm growth, including age older than 50 years, female sex, smoking history, and nonsaccular shape. These findings should be considered when counseling patients regarding the natural history of unruptured intracranial aneurysms.

Emerging techniques for evaluation of the hemodynamics of intracranial vascular pathology

Advances in imaging modalities have improved the assessment of intracranial hemodynamics using non-invasive techniques. This review examines new imaging modalities and clinical applications of currently available techniques, describes pathophysiology and future directions in hemodynamic analysis of intracranial stenoses, aneurysms and arteriovenous malformations and explores how hemodynamic analysis may have prognostic value in predicting clinical outcomes and assist in risk stratification. The advent of new technologies such as pseudo-continuous arterial spin labeling, accelerated magnetic resonance angiography (MRA) techniques, 4D digital subtraction angiography, and improvements in clinically available techniques such as phase-contrast MRA may change the landscape of vascular imaging and modify current clinical practice guidelines.

Changes of size and shape of small, unruptured intracranial aneurysms in repeated computed tomography angiography studies

Introduction

Unruptured intracranial aneurysms (UIAs) are frequently detected in noninvasive imaging studies such as computed tomography angiography (CTA) or magnetic resonance angiography (MRA). If small, UIAs are observed in these modalities in order to detect growth or shape change, but there are many questions about proper protocol of the follow-up.

Aim

To assess changes of small (< 7 mm) UIAs dome size and shape in repeated CTA studies as predictors of growth and rupture.

Material and methods

One hundred and ten UIAs (10 posterior circulation) in 70 patients (55 women) were observed, with a cumulative observation time of 333.32 years. Aneurysms’ dome and neck perpendicular dimensions were measured in the first and the last CTA study at least twice with the developed application. Confidence intervals (CI) for measurements and dome shape parameters were calculated. For aneurysms ruptured during follow-up intermediate studies were analyzed. Patients’ clinical information was recorded. The aneurysm growth detection algorithm integrated CI and spatial resolution of the CT scanner.

Results

Twenty-three aneurysms increased in volume, 10 in height and 14 in dome width. Volume increased in 90% of cases of height and 93% of width increase. Posterior circulation aneurysms grew faster than anterior ones (p < 0.003), but calculated time to significant size increase (eT) did not differ between the groups due to higher CI in the posterior circulation. Analysis of eT with Kaplan-Meier curves showed that 75% of growing aneurysms could be detected in the first 3 years of observation. During the follow-up 3 aneurysms bled, and they grew faster than other growing aneurysms. Two of the bleeding aneurysms formed daughter sacs.

Conclusions

Dome volume assessment is superior to single dimension assessment in aneurysm growth detection. Confidence intervals assessment helps to avoid overestimation of growth. Seventy-five percent of growing aneurysms could be detected in the first 3 years of observation. Daughter sac formation and fast increase in size are strong predictors of aneurysm rupture.

Elevated relative risk of aneurysmal subarachnoid hemorrhage with colder weather in the mid-Atlantic region

We have previously reported an increase of 0.6% in the relative risk of aneurysmal subarachnoid hemorrhage (aSAH) in response to every 1°F decrease in the maximum daily temperature (Tmax) in colder seasons from patients presenting to our regional tertiary care center. We hypothesized that this relationship would also be observed in the warmer summer months with ambient temperatures greater than 70°F. From prospectively collected incidence data for aSAH patients, we investigated absolute Tmax, average daily temperatures, intraday temperature ranges, and the variation of daily Tmax relative to 70°F to assess associations with aSAH incidence for patients admitted to our institution between 1991 and 2009 during the hottest months and days on which Tmax>70°F. For all days treated as a group, the mean Tmax (± standard deviation) was lower when aSAH occurred than when it did not (64.4±18.2°F versus 65.8±18.3°F; p=0.016). During summer months, the odds ratio (OR) of aSAH incidence increased with lower mean Tmax (OR 1.019; 95% confidence interval 1.001-1.037; p=0.043). The proportion of days with aSAH admissions was lower on hotter days than the proportion of days with no aSAH (96% versus 98%; p=0.006). aSAH were more likely to occur during the summer and on days with a temperature fluctuation less than 10°F (8% versus 4%; p=0.002). During the hottest months of the year in the mid-Atlantic region, colder maximum daily temperatures, a smaller heat burden above 70°F, and smaller intraday temperature fluctuations are associated with increased aSAH admissions in a similar manner to colder months. These findings support the hypothesis that aSAH incidence is more likely with drops in temperature, even in the warmer months.

AView: An Image-based Clinical Computational Tool for Intracranial Aneurysm Flow Visualization and Clinical Management

Intracranial aneurysms (IAs) occur in around 3% of the entire population. IA rupture is responsible for the most devastating type of hemorrhagic strokes, with high fatality and disability rates as well as healthcare costs. With increasing detection of unruptured aneurysms, clinicians are routinely faced with the dilemma whether to treat IA patients and how to best treat them. Hemodynamic and morphological characteristics are increasingly considered in aneurysm rupture risk assessment and treatment planning, but currently no computational tools allow routine integration of flow visualization and quantitation of these parameters in clinical workflow. In this paper, we introduce AView, a prototype of a clinician-oriented, integrated computation tool for aneurysm hemodynamics, morphology, and risk and data management to aid in treatment decisions and treatment planning in or near the procedure room. Specifically, we describe how we have designed the AView structure from the end-user's point of view, performed a pilot study and gathered clinical feedback. The positive results demonstrate AView's potential clinical value on enhancing aneurysm treatment decision and treatment planning.

Guidelines for the Management of Patients With Unruptured Intracranial Aneurysms: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

PURPOSE

The aim of this updated statement is to provide comprehensive and evidence-based recommendations for management of patients with unruptured intracranial aneurysms.

METHODS

Writing group members used systematic literature reviews from January 1977 up to June 2014. They also reviewed contemporary published evidence-based guidelines, personal files, and published expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulated recommendations using standard American Heart Association criteria. The guideline underwent extensive peer review, including review by the Stroke Council Leadership and Stroke Scientific Statement Oversight Committees, before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee.

RESULTS

Evidence-based guidelines are presented for the care of patients presenting with unruptured intracranial aneurysms. The guidelines address presentation, natural history, epidemiology, risk factors, screening, diagnosis, imaging and outcomes from surgical and endovascular treatment.

PHASES Score for Prediction of Intracranial Aneurysm Growth

BACKGROUND AND PURPOSE

Growth of an intracranial aneurysm occurs in around 10% of patients at 2-year follow-up imaging and may be associated with aneurysm rupture. We investigated whether PHASES, a score providing absolute risks of aneurysm rupture based on 6 easily retrievable risk factors, also predicts aneurysm growth.

METHODS

In a multicenter cohort of patients with unruptured intracranial aneurysms and follow-up imaging with computed tomography angiography or magnetic resonance angiography, we performed univariable and multivariable Cox regression analyses for the predictors of the PHASES score at baseline, with aneurysm growth as outcome. We calculated hazard ratios and corresponding 95% confidence intervals (CI), with the PHASES score as continuous variable and after division into quartiles.

RESULTS

We included 557 patients with 734 unruptured aneurysms. Eighty-nine (12%) aneurysms in 87 patients showed growth during a median follow-up of 2.7 patient-years (range 0.5-10.8). Per point increase in PHASES score, hazard ratio for aneurysm growth was 1.32 (95% CI, 1.22-1.43). With the lowest quartile of the PHASES score (0-1) as reference, hazard ratios were for the second (PHASES 2-3) 1.07 (95% CI, 0.49-2.32), the third (PHASES 4) 2.29 (95% CI, 1.05-4.95), and the fourth quartile (PHASES 5-14) 2.85 (95% CI, 1.43-5.67).

CONCLUSIONS

Higher PHASES scores were associated with an increased risk of aneurysm growth. Because higher PHASES scores also predict aneurysm rupture, our findings suggest that aneurysm growth can be used as surrogate outcome measure of aneurysm rupture in follow-up studies on risk prediction or interventions aimed to reduce the risk of rupture.

Clinical, Radiological, and Flow-Related Risk Factors for Growth of Untreated, Unruptured Intracranial Aneurysms

Background and Purpose—

Unruptured intracranial aneurysms are frequently followed to monitor aneurysm growth. We studied the yield of follow-up imaging and analyzed risk factors for aneurysm growth.

Methods—

We included patients with untreated, unruptured intracranial aneurysms and ≥6 months of follow-up imaging from 2 large prospectively collected databases. We assessed the proportion of patients with aneurysm growth and performed univariable and multivariable Cox regression analyses to calculate hazard ratios with corresponding 95% confidence intervals (CI) for clinical and radiological risk factors for aneurysm growth. We repeated these analyses for the subset of small (<7 mm) aneurysms.

Results—

Fifty-seven (12%) of 468 aneurysms in 363 patients grew during a median follow-up of 2.1 years (total follow-up, 1372 patient-years). In multivariable analysis, hazard ratios for aneurysm growth were as follows: 1.1 (95% CI, 1.0–1.2) per each additional mm of initial aneurysm size; 2.7 (95% CI, 1.2–6.4) for dome > neck ratio; 2.1 (95% CI, 0.9–4.9) for location in the posterior circulation; and 2.0 (95% CI, 0.8–4.8) for multilobarity. In the subset of aneurysms <7 mm, 37 of 403 (9%) enlarged. In multivariable analysis, hazard ratios for aneurysm growth were 1.1 (95% CI, 0.8–1.5) per each additional mm of initial aneurysm size, 2.2 (95% CI, 1.0–4.8) for smoking, 2.9 (95% CI, 1.0–8.5) for multilobarity, 2.4 (95% CI, 1.0–5.8) for dome/neck ratio, and 2.0 (95% CI, 0.6–7.0) for location in the posterior circulation.

Conclusions—

Initial aneurysm size, dome/neck ratio, and multilobarity are risk factors for aneurysm growth. Cessation of smoking is pivotal because smoking is a modifiable risk factor for growth of small aneurysms.

Female sex as a risk factor for the growth of asymptomatic unruptured cerebral saccular aneurysms in elderly patients

Object

The prevalence of patients with asymptomatic unruptured intracranial aneurysms (UIAs) increases with the advancing age of the general population. The goal of the present study was to identify risk factors for the growth of UIAs detected with serial MR angiography (MRA) in patients 70 years of age or older.

Methods

This prospective study enrolled 79 patients (age range 70–84 years) with 98 UIAs. Patients were followed up every 4 months, including an assessment of the aneurysm diameter and morphological changes on MRA, neurological status, and other medical conditions. Aneurysm growth was categorized into two different patterns on the basis of the MRA findings: 1) maximum increase in aneurysm diameter of 2 mm or more; and 2) obvious morphological change, such as the appearance of a bleb.

Results

The mean duration of follow-up was 38.5 months (250.2 patient-years). Aneurysm rupture did not occur, but aneurysm growth was observed in 8 aneurysms (8 patients) during the study period. Univariate analysis showed that female sex, patient age ≥ 75 years, and an aneurysm location in the internal carotid artery (ICA) or middle cerebral artery (MCA) were associated with aneurysm growth (p = 0.04, p = 0.04, and p < 0.001, respectively). Multivariate analysis demonstrated that female sex was the only independent predictor of aneurysm growth (p = 0.0313, OR 2.3, 95% CI 1.3–30.2).

Conclusions

Female sex is an independent risk factor for the growth of UIAs in elderly patients. In addition, an age ≥ 75 years and aneurysm location in the ICA or MCA are characteristics that may warrant additional attention during follow-up imaging.