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Background and Objectives: Advances in endovascular flow diverters have led to a secular shift in the management of brain aneurysms, causing debate on current bypass indications. We therefore sought to investigate the long-term results, current indications, and trends of bypasses for brain aneurysms., Methods: We retrospectively reviewed bypasses performed between 2005 and 2022 to treat brain aneurysms. Demographic, clinical, and radiological data were collected till the most recent follow-up. Aneurysm occlusion and graft patency was noted on cerebral angiogram in the immediate postoperative, 3-month, and most recent follow-up periods. Clinical outcomes (modified Rankin scores) and complications were assessed at 3 month and most recent follow-up. Trends in bypass volume and graft patency were assessed in 5-year epochs. Results were dichotomized based on aneurysm location to generate location-specific results and trends., Results: Overall, 203 patients (mean age 50 years, 57% female patients) with 207 cerebral aneurysms were treated with 233 cerebral bypasses with a mean follow-up of 2 years. Fusiform morphology was the most common bypass indication. Aneurysm occlusion on immediate postoperative and final follow-up angiogram was 89% (184/207) and 96% (198/207), respectively. Graft patency rate in the immediate postoperative period and most recent follow-up was 95% (222/233) and 92% (215/233), respectively. Of 207 aneurysms, 5 (2%) recurred. Of 203 patients, 81% (165) patients had modified Rankin scores of 0-2 at the 3-month follow-up and 11 patients died (mortality 5%). Although there was a steady decrease in the bypass volume over the study period, the proportion of bypasses for recurrent aneurysms increased serially. Posterior circulation aneurysms had lower rates of aneurysm occlusion and significantly higher incidence of postoperative strokes and deaths ( P = .0035), with basilar artery aneurysms having the worst outcomes., Conclusion: Bypass indications have evolved with the inception of novel flow diverters. However, they remain relevant in the cerebrovascular surgeon's armamentarium, and long-term results are excellent., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Subacute in-stent thrombosis is a rare but potentially fatal condition that can occur after treatment for intracranial aneurysms or stenosis. While immediate and late thromboembolic post-stent complications are well-described, subacute (2-30 days post-intervention) thrombosis is unusual. The administration of peri-operative dual anti-platelet therapy (DAPT) has significantly reduced the risk for thrombosis, but questions remain as to the choice of agents and treatment of thromboembolic complications in this setting. We present our acute endovascular management strategies for three patients who suffered thromboembolic complications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Ideal management of unruptured intracranial aneurysms (UIAs) and ruptured intracranial aneurysms (RIAs) is a controversial issue. Over the last few decades, a significant paradigm shift has occurred away from open microsurgical clipping toward endovascular coil embolization. Multiple studies have been performed with mixed results. Some studies suggest that endovascular treatment produces better clinical and functional outcomes, but is associated with increased need for retreatment. Other studies report increased durability in aneurysms treated with microsurgical clipping, but that clipping may be associated with worse functional outcomes in some cases. Further complicating the dialogue are variable costs associated with different treatment modalities, including country-dependent cost differences. Here we provide a review of some of the major studies comparing open surgery versus endovascular treatment for both RIAs and UIAs to distill their key findings and corresponding implications for clinical practice. We relate these research results to our institution's experience with RIAs and UIAs and describe our approach to treatment of these conditions. Finally, we discuss implications of the paradigm shift for both open and endovascular surgery, including educational initiatives directed toward preserving important microsurgical tenets in the setting of diminishing surgical volume., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To analyze a consecutive series of patients with middle cerebral artery (MCA) aneurysms who needed an adjunctive cerebral revascularization procedure to achieve aneurysm occlusion with preservation of flow through all MCA branches., Methods: A total of 42 patients with 43 MCA aneurysms underwent 52 bypass procedures over 13 years. The location of the aneurysm were M1 trunk, M1 bifurcation, M2 and beyond. The bypasses performed included intracranial bypasses (resection with end to end anastomosis, end to side implantation, side to side anastomosis, and short interposition graft), extraintracranial bypasses (superficial temporal to middle cerebral artery anastomosis, and radial artery bypass graft, or saphenous vein graft), double bypasses, Y-grafts, and combined techniques., Results: Forty-two of 43 aneurysms (98%) had patent bypasses at long-term follow-up. All 43 aneurysms were completely occluded at last follow-up. Six patients (14%) developed strokes related to the surgical treatment. At last follow-up, 36 patients had a modified Rankin score of 0-2, 5 patients had modified Rankin score 3-5, and 1 died. In this series, 31 (73.8%) patients improved, 8 (19%) patients had same functional status, and 3 (7.2%) patients deteriorated, including 1 patient who expired due to sepsis. The mean clinical follow-up duration was 39.3 months (0.4-124 months) and the mean radiological follow-up was 37 months (0.4-134 months)., Conclusions: Cerebral revascularization is an important adjunct for treating MCA aneurysms and can be done safely. The article provides the insights we gained by rising through the learning curve., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Endovascular treatment of intracranial aneurysms is associated with higher rates of recurrence and retreatment, though contemporary rates and risk factors for basilar tip aneurysms (BTAs) are less well-described., Objective: To characterize progression, retreatement, and retreated progression of BTAs treated with microsurgical or endovascular interventions., Methods: We retrospectively reviewed records for 141 consecutive BTA patients. We included 158 anterior communicating artery (ACoA) and 118 middle cerebral artery (MCA) aneurysms as controls. Univariate and multivariate analyses were used to calculate rates of progression (recurrence of previously obliterated aneurysms and progression of known residual aneurysm dome or neck), retreatment, and retreated progression. Kaplan-Meier analysis was used to characterize 24-mo event rates for primary outcome prediction., Results: Of 141 BTA patients, 62.4% were ruptured and 37.6% were unruptured. Average radiographical follow-up was 33 mo. Among ruptured aneurysms treated with clipping, there were 2 rehemorrhages due to recurrence (6.1%), and none in any other cohorts. Overall rates of progression (28.9%), retreatment (28.9%), and retreated progression (24.7%) were not significantly different between surgical and endovascular subgroups, though ruptured aneurysms had higher event rates. Multivariate modeling confirmed rupture status (P = .003, hazard ratio = 0.14) and aneurysm dome width (P = .005, hazard ratio = 1.23) as independent predictors of progression requiring retreatment. In a separate multivariate analysis with ACoA and MCA aneurysms, basilar tip location was an independent predictor of progression, retreatment, and retreated progression., Conclusion: BTAs have higher rates of progression and retreated progression than other aneurysm locations, independent of treatment modality. Rupture status and dome width are risk factors for progression requiring retreatment., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background: Results of and the complications encountered during surgery for very large and giant intracranial aneurysms are illustrated., Objective: To analyze a consecutive series of patients with very large and giant aneurysms treated with microsurgery., Methods: This retrospective study included seventy six very large and giant aneurysms which were managed by clipping and bypass technique. Sixty two (82%) aneurysms were located in anterior circulation, and 14 (18%) aneurysms were located in posterior circulation. The bypasses performed included local bypasses, extra-intracranial bypasses, double bypasses and combination techniques of external carotid-internal carotid (EC-IC) bypass and local bypasses., Results: 73 patients with 76 aneurysms were treated over 13 years. There were 44 very large and 32 giant aneurysms. Twenty-four patients presented with subarachnoid hemorrhage [SAH] (32%) while forty nine patients with 52 aneurysms (68%) were unruptured. These 73 patients underwent 63 bypass procedures with aneurysm occlusion and 13 clipping procedures. Out of 62 anterior circulation aneurysms, bypass surgery was performed in 49 patients while 13 underwent clipping. In posterior circulation aneurysms, all patients were treated with bypass procedures with proximal occlusion or trapping. In the ruptured group, 16 (67%) patients had postoperative modified Rankin Scale (mRs) 0-2, six patients (25%) had mRs 3-5, and two patients (8.4%) died. In the unruptured group, 45 patients (87%) had mRs 0-2, 3 patients (6%) had mRs 3-5, and four patients (7.6%) died., Conclusions: In this large series of very large and giant aneurysms treated with microsurgical clipping and bypasses, excellent results were obtained in the long term, in regards to aneurysm occlusion, functional status, and graft patency. Our experience will be very useful to other neurosurgeons who treat these complex lesions., Competing Interests: There are no conflicts of interest

Background: High-risk components of brain arteriovenous malformations (BAVMs) can be targeted to reduce the risk of lesion rupture., Objective: To evaluate targeted embolization of aneurysms against other means of treatment with a case-control analysis; we previously investigated this approach associated with BAVMs., Methods: Retrospective analysis of patients with BAVMs was performed, identifying patients treated with intention to occlude only an aneurysm associated with a BAVM. For each targeted aneurysm embolization (TAE) patient identified, 4 control patients were randomly selected, controlling for rupture status, age, and Spetzler-Martin plus Lawton-Young supplemental score. Analysis was performed to compare rates of adverse events (hemorrhage, new seizure, and death) between the 2 groups., Results: Thirty-two patients met inclusion criteria, and 128 control patients were identified, out of 1103 patients treated during the study period. Thirty-four adverse events occurred (15 ruptures, 15 new seizures, and 11 deaths) during the follow-up period (mean 1157 d for the TAE cohort and 1036 d for the non-TAE cohort). Statistically lower associations were noted for the TAE group for any adverse event (hazard ratio 0.28, P = .037) and the composite outcome of hemorrhage or new seizure (hazard ratio 0.20, P = .029)., Conclusion: For BAVMs at high risk for surgical resection, TAE can be performed safely and effectively. Patients treated with TAE had better outcomes than matched patients undergoing other combinations of treatment. TAE can be considered for BAVMs with high operative risk prior to radiosurgery or when no other treatment options are available., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: Cerebral bypass has been an important tool in the treatment of complex intracranial aneurysms. The recent advent of flow-diverting stents (FDS) has expanded the capacity for endovascular arterial reconstruction., Objective: We investigated how the advent of FDS has impacted the application and outcomes of cerebral bypass in the treatment of intracranial aneurysms., Methods: We reviewed a consecutive series of cerebral bypasses during aneurysm surgery over the course of 10 years. FDS were in active use during the last 5 years of this series. We compared the clinical characteristics, surgical technique, and outcomes of patients who required cerebral bypass for aneurysm treatment during the preflow diversion era (PreFD) with those of the postflow diversion era (PostFD)., Results: We treated 1061 aneurysms in the PreFD era (from July 2005 through June 2010) and 1348 in the PostFD era (from July 2010 through June 2015). Eighty-five PreFD patients (8%) and 45 PostFD patients (3%) were treated with cerebral bypass. PreFD patients had better baseline functional status compared to PostFD patients with average preoperative modified Rankin Scale score of 0.55 in PreFD and 1.18 in PostFD., Conclusion: After the introduction of FDS, cerebral bypass was performed in a lower proportion of patients with aneurysms. Patients selected for bypass in the flow-diverter era had worse preoperative modified Rankin Scale scores indicating a greater complexity of the patients. Cerebral bypass in well-selected patients and revascularization remains an important technique in vascular neurosurgery. It is also useful as a rescue technique after failed FDS treatment of aneurysms., (Copyright © 2017 by the Congress of Neurological Surgeons)

Introduction: To mitigate risks of hemorrhage, high-risk features of brain arteriovenous malformations (BAVMs) can be targeted to reduce the risk of rupture. Previous investigation has examined embolization of a pedicle supplying a high-risk feature; this study examines embolization targeted specifically at aneurysms associated with BAVMs., Materials and Methods: Patients with BAVMs treated at two high-volume neurointerventional services were retrospectively reviewed. Patients treated with intention to occlude only the associated aneurysm itself were analyzed. Demographic and lesion characteristics were identified, as were technical and clinical outcomes. Adverse events were defined as hemorrhage, new seizure, and death., Results: Thirty-two patients met inclusion criteria out of 1103 patients treated during the study period. Twenty-seven (84.4%) BAVMs were acutely ruptured, all with the aneurysm identified as the hemorrhage source. Twenty-four (75.0%) lesions involved eloquent territory. There were equal numbers of feeding artery and nidus aneurysms. Follow-up data were available for a total of 101.3 patient-years for a mean follow-up time of 2.9 years. One patient died; the remaining 31 patients had improved functional status at last contact. Annualized rate of hemorrhage after treatment was 1.0%; rate of adverse events after treatment was 3.0%. Excluding time after confirmed occlusion following radiosurgery, annualized rates were 1.4% and 4.8%, respectively., Conclusion: In inoperable BAVMs, targeted embolization of associated aneurysms can be performed safely and effectively. This should be considered in high-risk lesions prior to radiosurgery or in cases when no other treatment options are available. Such intervention warrants further investigation., (© The Author(s) 2016.)

Background: Blood blister type aneurysms (BBAs) and pseudoaneurysms create a unique treatment challenge. Despite many advances in open surgical and endovascular techniques, this subset of patients retains relatively high rates of morbidity and mortality. Recently, BBAs have been treated with flow-diverting stents such as the Pipeline Embolization Device (PED) with overall positive results., Methods: Four patients presented with dissecting internal carotid artery (ICA) aneurysms treated with the PED (two BBAs presenting with subarachnoid hemorrhage (SAH), two pseudoaneurysms after injury during endoscopic trans-sphenoidal tumor surgery)., Results: Three patients had a successful angiographic and neurological outcome. One patient with a BBA re-ruptured during initial PED placement, again in the postoperative period, and later died. Primary PED treatment involved telescoping stents in two patients and coil embolization supplementation in one patient., Conclusions: The PED should be used selectively in the setting of acute SAH. Dual antiplatelet therapy can complicate hydrocephalus management, and the lack of immediate aneurysm occlusion creates the risk of short-term re-rupture. PED treatment for iatrogenic ICA pseudoaneurysms can provide a good angiographic and neurological outcome., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Computational hemodynamic simulations of cerebral aneurysms have traditionally relied on stereotypical boundary conditions (such as blood flow velocity and blood pressure) derived from published values as patient-specific measurements are unavailable or difficult to collect. However, controversy persists over the necessity of incorporating such patient-specific conditions into computational analyses. We perform simulations using both endovascularly-derived patient-specific and typical literature-derived inflow and outflow boundary conditions. Detailed three-dimensional anatomical models of the cerebral vasculature are developed from rotational angiography data, and blood flow velocity and pressure are measured in situ by a dual-sensor pressure and velocity endovascular guidewire at multiple peri-aneurysmal locations in 10 unruptured cerebral aneurysms. These measurements are used to define inflow and outflow boundary conditions for computational hemodynamic models of the aneurysms. The additional in situ measurements which are not prescribed in the simulation are then used to assess the accuracy of the simulated flow velocity and pressure drop. Simulated velocities using patient-specific boundary conditions show good agreement with the guidewire measurements at measurement locations inside the domain, with no bias in the agreement and a random scatter of ≈25%. Simulated velocities using the simplified, literature-derived values show a systematic bias and over-predicted velocity by ≈30% with a random scatter of ≈40%. Computational hemodynamics using endovascularly measured patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics than those based on commonly accepted reference values for boundary conditions.

Background: Complex intracranial aneurysms are often treated with endovascular stent-assisted coiling. Intracranial stents are difficult to visualize with conventional computed tomography (CT) or fluoroscopy. "Stent view" flat-detector CT can be used to visualize intracranial stents during endovascular treatment., Methods: Three patients underwent endovascular treatment of complex intracranial aneurysms. Stent view flat-detector CT was used to study stent placement and morphology in vivo., Results: Stent view CT was successful in visualizing stents in all patients. In two patients, stent morphology rendered endovascular coiling technically unfeasible; in one patient, visualization of stent strut herniation into the aneurysm lumen allowed successful coil embolization of the aneurysm., Conclusions: Stent view CT provided detailed imaging of stent placement and morphology in all three cases. The technique influenced treatment decisions and technical outcomes. Stent view CT is a valuable intraprocedural technical tool in stent-assisted endovascular procedures., (Copyright © 2011 Elsevier Inc. All rights reserved.)