Background/Objectives: Endovascular treatment has become the primary treatment for intracranial aneurysms, yet direct bypass surgery remains an option in selected cases where standard approaches fail. This study aims to evaluate the role, indications, and outcomes of bypass surgery for intracranial aneurysm management in the current endovascular era. Methods: A single-center retrospective analysis was conducted on consecutive cases who underwent direct intracranial bypass surgery for intracranial aneurysms between 2015 and 2024. Data on demographics, aneurysm characteristics, indications, bypass type, patency, and clinical outcomes (using the modified Rankin Scale) were collected. Results: Of the 101 bypasses performed between 2015 and 2025, 25 were used for complex aneurysm cases. Intracranial bypass was necessary in as many as 5% of all microsurgical aneurysm repairs in 2023 and 10% in 2024. Bypass surgery was indicated in young patients with complex aneurysms not amenable to endovascular therapy (45%) and in 20% of the cases for recanalized aneurysms after previous endovascular repair. Intraoperative and postoperative bypass patency was confirmed for all patients except one case due to ongoing malignant brain swelling after an ongoing infarction. At follow-up, 87% of patients, with both ruptured and unruptured aneurysms, had a good outcome (mRS ≤ 2), and all patients had a patent bypass. Permanent morbidity was observed in 5% and procedure-related mortality in 0%. Conclusions: While bypass surgery constitutes a minority of intracranial aneurysm treatment by volume, its role in intracranial aneurysm repair is crucial and relevant in response to the evolving complexity of aneurysms. Further refinement of techniques is necessary.

The reliable visualization of deep cerebral perforating arteries is a challenge. Despite the advancements in high resolution imaging, the optimal modality to depict deep cerebral perforating arteries remains unclear. The purpose of this systematic review was to provide an overview of the imaging modalities used to visualize perforating arteries and to evaluate their diagnostic performance. EMBASE, Ovid Medline, the Web of Science Core Collection, Google Scholar, and Cochrane Central Register of Controlled Trials were searched from database inception to April 15th, 2025. Original studies using imaging modalities to depict perforating arteries in human subjects were included. The search strategy yielded 3,857 articles of which 1,725 remained after removing duplicates. After the initial sift phase, 215 articles remained to be assessed for eligibility based on full-text sifting. Finally, 106 studies (6,785 participants;14,041 hemispheres) were included. As a performance measure, detection rate was defined as the percentage of participants in which at least one perforating artery in one arterial territory could be detected. Pooled estimate (%) of detection rate per imaging modality was calculated using a random-effects model with a 95% confidence interval (CI). Studies used 7T MRA/MRI (n=56), 3T MRA/MRI (n=32), 1.5T MRA/MRI (n=6), CTA (n=4), CT (n=1), DSA (n=14), and transcranial ultrasound (n=3). Pooled estimates found a detection rate of 94% (95% CI 0.90-0.97; I²=64%) for 7T MRA/MRI and 85% (95% CI 0.63-0.95; I²=84%) for 3T MRA/MRI. One 3T MRA study performed an in-vivo diagnostic validation study by direct intraoperative evaluation. Our findings have not been validated in-vivo. Multiple imaging modalities including 7T, 3T, and 1.5T MRA/MRI, CTA, and DSA, have been used to visualize deep cerebral perforating arteries. High-resolution MRI, particularly 7T MRA, shows the highest detection rates (up to 94%), although most studies were performed in healthy volunteers and lacked anatomical validation. Consequently, reported detection rates may overestimate true vessel visualization. Future research should prioritize rigorous in-vivo validation of these techniques to establish their clinical reliability.

Background/Objectives: The anterior communicating artery (AcomA) is one of the most common sites of intracranial aneurysms. We aimed to investigate the effect of routine extradural anterior clinoidectomy (EAC) and extradural lamina terminalis fenestration (ELTF) on the incidence of shunt-dependent hydrocephalus (SDH) and gyrus rectus injury in patients undergoing microsurgical clip reconstruction. Methods: This matched case–control study included 15 patients treated with routine EAC/ELTF between July 2023 and June 2025, matched 1:2 to 30 historical controls (2000–2019) by aneurysm size, location, dome-to-neck ratio, and rupture status. The primary outcome was the incidence of SDH. The secondary outcomes included the incidence of gyrus rectus hypodensity/injury and clinical outcomes, as assessed by the modified Rankin Scale (mRS) at discharge and follow-up. Results: Among 15 cases, 6 had ruptured aneurysms, 4 had unruptured aneurysms, and 5 were recanalized post-endovascular treatment. EAC was performed in all cases; ELTF was performed in 83% of ruptured cases. SDH occurred in 33% of ruptured cases versus 90% in controls (p = 0.02). Gyrus rectus hypodensity occurred in 13% of cases vs. 50% of controls (p = 0.01). EAC/ELTF was associated with reduced odds of SDH (OR: 0.06; 95% CI: 0.004–0.80; p = 0.03) and gyrus rectus hypodensity (OR: 0.15; 95% CI: 0.03–0.80; p = 0.03). A poor outcome (mRS >2) was seen in 27% at discharge, improving to 14% at follow-up (with a median of 11 months). Delayed cerebral ischemia occurred in 33% of ruptured cases. Conclusions: Routine EAC/ELTF may reduce SDH and gyrus rectus injury after AComA aneurysm clip reconstruction, particularly in ruptured cases. Prospective multi-center studies are needed to validate these preliminary findings.

BACKGROUND: Knowledge of the anatomic distribution of cerebral perforating arteries and the consequences of ischemia in these territories is limited. This study aims to evaluate the effect of perforator territory ischemia on functional outcome in patients with anterior circulation large vessel occlusion. METHODS: A post hoc analysis of the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands, MR CLEAN-MED (Safety and Efficacy of Aspirin, Unfractionated Heparin, Both, or Neither During Endovascular Stroke Treatment) and MR CLEAN-NO IV (Intravenous Treatment Followed by Intra-Arterial Treatment Versus Direct Intra-Arterial Treatment for Acute Ischemic Stroke Caused by a Proximal Intracranial Occlusion) participants, recruited between January 2018 and January 2021 from 20 European stroke centers, was performed. Patients undergoing endovascular thrombectomy for anterior circulation large vessel occlusion with available posttreatment magnetic resonance imaging were included. Patients were assigned to 3 groups based on infarct location identified on ≤24 hours posttreatment magnetic resonance imaging: cortex group, perforator and insular group, and both groups (cortical alongside insular and perforator territory). Multivariable linear and ordinal regression analyses were performed separately with the National Institutes of Health Stroke Scale score at 24 hours as the primary outcome and modified Rankin Scale at 90 days as the secondary outcome, adjusted for baseline scores and prognostic factors. RESULTS: Out of 1167 patients, a total of 397 were included. The median age was 71 (interquartile range, 62–79), and 204 (51%) were men. Although no significant association was found in multivariable analysis between perforator territory infarctions and 24 hours National Institutes of Health Stroke Scale, patients with perforator territory ischemia were more likely to have a worse 90-days modified Rankin Scale (median modified Rankin Scale, 2 [interquartile range, 1–3]; common odds ratio, 2.94 [95% CI, 1.73–4.98]). Besides infarct locations, Thrombolysis in Cerebral Infarction grade 2B-3 and Heidelberg bleeding classifications 1c and 2 significantly influenced the 24-hour National Institutes of Health Stroke Scale and 90-day modified Rankin Scale outcomes. CONCLUSIONS: Patients with anterior circulation large vessel occlusion leading to perforator territory infarctions are more likely to have an unfavorable functional outcome at 90 days. Future research should focus on better visualization of perforating arteries and understanding their functional anatomy to prevent perforator territory ischemia and improve patient outcomes.