Machine Learning–Based Rupture Risk Prediction for Intracranial Aneurysms: A Systematic Review and Meta-Analysis

Neurosurgery 97:1072–1082, 2025

This systematic review and meta-analysis evaluates machine learning (ML) applications for predicting intracranial aneurysm rupture, comparing 124 ML models across 36 retrospective studies (22,462 patients) with the PHASES score. Results show ML—especially deep learning and SVM—achieves higher AUC and specificity than PHASES, with hemodynamic inputs improving test-set specificity but not external validation.

The authors highlight methodological heterogeneity, risks of bias, and overfitting concerns from retrospective single‑center data, urging prospective, standardized studies and external validation before clinical integration of ML rupture‑risk tools.

Machine Learning (ML) Models: ML techniques, including deep learning (DL), support vector machines (SVM), and regression models, show higher specificity and overall diagnostic accuracy than the traditional PHASES score for predicting intracranial aneurysm rupture risk, with comparable sensitivity.

• Deep Learning Performance: DL models achieved the highest sensitivity (up to 0.87), specificity (up to 0.86), and area under the curve (AUC-ROC up to 0.92) among all ML families, indicating strong discriminative ability in rupture risk prediction.

• PHASES Score Limitations: The PHASES score, though widely used, demonstrates lower specificity (0.51) and modest overall discriminative ability (AUC-ROC 0.66), and does not incorporate important risk factors like aneurysm morphology or family history.

• Hemodynamic Parameters: Incorporating hemodynamic variables (e.g., wall shear stress, flow patterns) into ML models improves specificity and accuracy in test sets, but benefits are less pronounced in external validation, possibly due to sample size and generalizability issues.

• Retrospective Data and Overfitting: All included ML models were trained on retrospective, post-rupture data, raising concerns about overfitting and the applicability of these models to pre-rupture clinical decision-making.

• Generalizability Concerns: ML models often perform less well on external validation data due to biases in patient selection, single-center data, and differences in imaging or clinical protocols, while the PHASES score maintains more consistent performance across settings.

• Need for Prospective Validation: There is a critical need for prospective studies and standardized protocols to confirm the clinical utility and reliability of ML-based rupture risk prediction models before integration into routine practice.

• Clinical Implications: ML approaches, especially DL and SVM, have the potential to enhance individualized risk stratification and reduce overtreatment, but methodological challenges and validation in diverse populations remain essential for safe clinical adoption.

Microsurgical treatment of ruptured aneurysms beyond 72 hours after rupture: implications for advanced management

Acta Neurochirurgica (2022) 164:2431–2439

Aneurysmal subarachnoid hemorrhage (aSAH) patients admitted to primary stroke centers are often transferred to neurosurgical and endovascular services at tertiary centers. The effect on microsurgical outcomes of the resultant delay in treatment is unknown. We evaluated microsurgical aSAH treatment > 72 h after the ictus.

Methods All aSAH patients treated at a single tertiary center between August 1, 2007, and July 31, 2019, were retrospectively reviewed. The additional inclusion criterion was the availability of treatment data relative to time of bleed. Patients were grouped based on bleed-to-treatment time as having acute treatment (on or before postbleed day [PBD] 3) or delayed treatment (on or after PBD 4). Propensity adjustments were used to correct for statistically significant confounding covariables.

Results Among 956 aSAH patients, 92 (10%) received delayed surgical treatment (delayed group), and 864 (90%) received acute endovascular or surgical treatment (acute group). Reruptures occurred in 3% (26/864) of the acute group and 1% (1/92) of the delayed group (p = 0.51). After propensity adjustments, the odds of residual aneurysm (OR = 0.09; 95% CI = 0.04–0.17; p < 0.001) or retreatment (OR = 0.14; 95% CI = 0.06–0.29; p < 0.001) was significantly lower among the delayed group. The OR was 0.50 for rerupture, after propensity adjustments, in the delayed setting (p = 0.03). Mean Glasgow Coma Scale scores at admission in the acute and delayed groups were 11.5 and 13.2, respectively (p < 0.001).

Conclusions Delayed microsurgical management of aSAH, if required for definitive treatment, appeared to be noninferior with respect to retreatment, residual, and rerupture events in our cohort after adjusting for initial disease severity and significant confounding variables.

Current surgical results with low-grade brain arteriovenous malformations

Low-grade brain arteriovenous malformations

J Neurosurg 122:912–920, 2015

Resection is an appealing therapy for brain arteriovenous malformations (AVMs) because of its high cure rate, low complication rate, and immediacy, and has become the first-line therapy for many AVMs. To clarify safety, efficacy, and outcomes associated with AVM resection in the aftermath of A Randomized Trial of Unruptured Brain AVMs (ARUBA), the authors reviewed their experience with low-grade AVMs—the most favorable AVMs for surgery and the ones most likely to have been selected for treatment outside of ARUBA’s randomization process.

Methods A prospective AVM registry was searched to identify patients with Spetzler-Martin Grade I and II AVMs treated using resection during a 16-year period.

Results Of the 232 surgical patients included, 120 (52%) presented with hemorrhage, 33% had Spetzler-Martin Grade I, and 67% had Grade II AVMs. Overall, 99 patients (43%) underwent preoperative embolization, with unruptured AVMs embolized more often than ruptured AVMs. AVM resection was accomplished in all patients and confirmed angiographically in 218 patients (94%). There were no deaths among patients with unruptured AVMs. Good outcomes (modified Rankin Scale [mRS] score 0–1) were found in 78% of patients, with 97% improved or unchanged from their preoperative mRS scores. Patients with unruptured AVMs had better functional outcomes (91% good outcome vs 65% in the ruptured group, p = 0.0008), while relative outcomes were equivalent (98% improved/unchanged in patients with ruptured AVMs vs 96% in patients with unruptured AVMs).

Conclusions Surgery should be regarded as the “gold standard” therapy for the majority of low-grade AVMs, utilizing conservative embolization as a preoperative adjunct. High surgical cure rates and excellent functional outcomes in patients with both ruptured and unruptured AVMs support a dominant surgical posture for low-grade AVMS, with radiosurgery reserved for risky AVMs in deep, inaccessible, and highly eloquent locations. Despite the technological advances in endovascular and radiosurgical therapy, surgery still offers the best cure rate, lowest risk profile, and greatest protection against hemorrhage for low-grade AVMs. ARUBA results are influenced by a low randomization rate, bias toward nonsurgical therapies, a shortage of surgical expertise, a lower rate of complete AVM obliteration, a higher rate of delayed hemorrhage, and short study duration. Another randomized trial is needed to reestablish the role of surgery in unruptured AVM management.