Scoring of Growth of Unruptured Intracranial Aneurysms

The incidence and prevalence of unruptured intracranial aneurysms in sickle cell disease patients: a systematic review

BACKGROUND

Unruptured Intracranial Aneurysms (UIAs) pose a significant risk of morbidity in the general population and much more so among sickle cell disease (SCD) patients. Meanwhile, the proportion of these patients with UIAs is not established just as the course and characteristics of the aneurysms are not well known.

AIM

To estimate the prevalence, incidence and characteristics of UIAs in SCD patients and compare same with the metrics and features in the general population.

METHODS

The Data repositories, Medline (PubMed), Embase and Web of science were systematically searched from January 1st, 1990, to July 31st, 2021. Publications that passed an inclusion test were reviewed for data on the incidence and prevalence of UIAs, aneurysm characteristics and outcomes in SCD patients extracted. Findings from the included studies were appraised, using the Methodological Index for Non-randomized studies score (MINORS). The results were descriptively analysed. Given the marked heterogeneity of retrieved data, results were reported as standardized values, including the mean weighted annual incidence rate.

RESULTS

105 SCD patients with 186 UIAs were identified in 10 retrospective studies. Mean age ranged from 10.5 to 40.18 across studies with adult (>18 years) predominance. The prevalence of UIAs in SCD was 4.1% (95%CI 3.6 and 4.6) incidence rate was 1290.3/100,000 patient-years (95% CI 1018.0-1562.6). Aneurysms tended to be small (60%), anterior (76.1%), multiple (45.7%), and managed conservatively (62%) with mostly good outcomes (95%). The average MINORS score was 9.4 ± 3.1 for non-comparative studies (n = 8) and 19.5 ± 0.7 for comparative studies (n = 2).

CONCLUSION

UIAs have a definite relationship with SCD, with higher incidence figures relative to the general population. Aneurysmal characteristics although largely similar, tend to be smaller in SCD patients. The low methodological quality of reviewed studies informs the need for well-designed prospective randomized controlled studies to better understand the mechanics of this relationship.

Predicting the growth of middle cerebral artery bifurcation aneurysms using differences in the bifurcation angle and inflow coefficient

OBJECTIVE

Growing intracranial aneurysms (IAs) are prone to rupture. Previous cross-sectional studies using postrupture morphology have shown the morphological or hemodynamic features related to IA rupture. Yet, which morphological or hemodynamic differences of the prerupture status can predict the growth and rupture of smaller IAs remains unknown. The purpose of this longitudinal study was to investigate the effects of morphological features and the hemodynamic environment on the growth of IAs at middle cerebral artery (MCA) bifurcations during the follow-up period.

METHODS

One hundred two patients with MCA M1–2 bifurcation saccular IAs who underwent follow-up for more than 2 years at the authors’ institutions between 2011 and 2019 were retrospectively identified. During the follow-up period, cases involving growth of MCA IAs were assigned to the event group, and those with MCA IAs unchanged in size were assigned to the control group. The morphological parameters examined were aneurysmal neck length, dome height, aspect ratio and volume, M1 and M2 diameters and their ratio, and angle configurations among M1, M2, and the aneurysm. Hemodynamic parameters were flow rate and wall shear stress in M1, M2, and the aneurysm, including the aneurysmal inflow rate coefficient (AIRC), defined as the ratio of the aneurysmal inflow rate to the M1 flow rate. Those parameters were compared statistically between the two groups. Correlations between morphological and hemodynamic parameters were also examined.

RESULTS

Eighty-three of 102 patients were included: 25 with growing MCA IAs (event group) and 58 with stable MCA IAs (control group). The median patient age at initial diagnosis was 66.9 (IQR 59.8–72.3) years. The median follow-up period was 48.5 (IQR 36.5–65.6) months. Both patient age and the AIRC were significant independent predictors of the growth of MCA IAs. Moreover, the AIRC was strongly correlated with sharper bifurcation and inflow angles, as well as wider inclination angles between the M1 and M2 arteries.

CONCLUSIONS

The AIRC was a significant independent predictor of the growth of MCA IAs. Sharper bifurcation and inflow angles and wider inclination angles between the M1 and M2 arteries were correlated with the AIRC. MCA IAs with such a bifurcation configuration are more prone to grow and rupture.

Timing and outcome of bystanders treatment in patients with subarachnoid hemorrhage associated with multiple aneurysms

In case of subarachnoid hemorrhage (SAH) associated with multiple intracranial aneurysms (MIAs), the main goal of acute treatment is securing the source of bleeding (index aneurysm). Indications and timing of bystanders treatment are instead still debated as the risk of new SAHs in patients harboring MIAs is not yet established. However, even if technically feasible, a simultaneous management of all aneurysms remains questionable, especially for safety issues. We retrospectively reviewed our last 5-year experience with SAH patients harboring MIAs entered in a clinic-radiological monitoring for bystanders follow-up in order to evaluate the occurrence of morphological changes, bleeding events, and safety and efficacy of a delayed treatment. We included 39 patients with mean age of 59.5 ± 12.2 years who survived a SAH. Among them, 14 underwent treatment, whereas 25 continued follow-up. The mean time between index and bystanders treatment was 14.3 ± 19.2 months. Patients undergoing bystanders treatment were mainly female and in general younger than patients undergoing observation. No cases of growth or bleeding were observed among bystanders within the two groups during the follow-up, which was longer than 1 year for the intervention group, and almost 40 months for the observation group. No major complications and mRS modifications were observed after bystanders treatment. Our data seem to suggest that within the short follow-up, intervention and observation seem to be likewise safe for bystander aneurysms, showing at the same time that a delayed management presents a similar risk profile of treating unruptured aneurysms in patients with no previous history of SAH.

Machine Learning and Intracranial Aneurysms: From Detection to Outcome Prediction

Machine learning (ML) is a rapidly rising research tool in biomedical sciences whose applications include segmentation, classification, disease detection, and outcome prediction. With respect to traditional statistical methods, ML algorithms have the potential to learn and improve their predictive performance when fed with large data sets without the need of being specifically programmed. In recent years, this technology has been increasingly applied for tackling clinical issues in intracranial aneurysm (IA) research. Several studies attempted to provide reliable models for enhanced aneurysm detection. Convolutional neural networks trained with variable degrees of human interaction on data from diverse imaging modalities showed high sensitivity in aneurysm detection tasks, also outperforming expert image analysis. Algorithms were also shown to differentiate ruptured from unruptured IAs, with however limited clinical relevance. For prediction of rupture and stability assessment, ML was preliminarily shown to achieve better performance compared to conventional statistical methods and existing risk scores. ML-based complication and functional outcome prediction in the event of SAH have been more extensively reported, in contrast with periprocedural outcome investigation in unruptured IA patients. ML has the potential to be a game changer in IA patient management. Currently clinical translation of experimental results is limited.

Risk Factors of Anterior Circulation Intracranial Aneurysm Rupture: Extracranial Carotid Artery Tortuosity and Aneurysm Morphologic Parameters

Background: This study was conducted to explore the risk factors of anterior circulation intracranial aneurysm rupture based on extracranial carotid artery (ECA) tortuosity.

Methods: This retrospective study, conducted from January 1, 2017, to March 1, 2021, collected and reviewed the clinical and imaging data of 308 patients with anterior circulation intracranial aneurysm [133 (43.2%) patients in the ruptured aneurysm group; 175 (56.8%) patients in the unruptured aneurysm group]. Computed tomography angiography (CTA) of the head and neck was used to determine the ECA tortuosity (normal, simple tortuosity, kink, coil) and the morphologic parameters of the aneurysms. The relationship of aneurysm rupture to ECA tortuosity and the morphologic parameters were analyzed.

Results: After univariate analysis, kink, angle of flow inflow (FA), aspect ratio (AR), aneurysm length (L), the distance from the tortuosity to the aneurysm (distance), and size ratio (SR) were significantly correlated with anterior circulation intracranial aneurysm rupture (p < 0.05). Spearman correlation analysis showed that ECA tortuosity was correlated with FA and SR (p < 0.05). Multiple logistic analyses showed that FA [odds ratio (OR), 1.013; 95% CI, 1.002–1.025], SR (OR, 1.521; 95% CI, 1.054–2.195), and kink (OR, 1.823; 95% CI, 1.074–3.096) were independently associated with aneurysm rupture.

Conclusion: Study results suggest that FA, SR, and ECA kink were independent risk factors associated with anterior circulation intracranial aneurysm rupture.

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.

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.