OBJECTIVE: Thromboembolic (TE) events are among the most feared complications after flow diversion (FD) and have been reported to occur even with adequate dual antiplatelet therapy. Herein, the authors characterize thrombotic and embolic events that developed after FD, focusing on the morbidity of each of these events and the predisposing factors associated with their development.
METHODS: A retrospective analysis of aneurysms treated with FD at a single institution in the US between 2013 and 2023 was performed. The authors documented the emergence of intraprocedural and postoperative TE events. A survival analysis and a Cox regression model was conducted to identify predictors associated with these events.
RESULTS: The authors included 651 procedures performed in 591 patients to treat 746 aneurysms. TE events occurred in 38 of the procedures performed (5.8%), causing permanent deficit in 20 patients and death in 4 patients. Eleven cases presented with acute stent thrombosis, 11 with large-vessel occlusion, and 9 with perforator strokes. At a median follow-up of 9.5 months, 73.0% of patients with an ischemic event had a modified Rankin Scale score ≤ 2. Three of the deaths were secondary to occlusion at the basilar trunk and vertebral artery. In patients with TE events in the anterior circulation, 7 of 11 patients with middle cerebral artery occlusion and 9 of 12 patients with internal carotid artery occlusion achieved independence. Time-to-event Cox regression analysis demonstrated that TE events were more frequent in patients exhibiting aspirin resistance (hazard ratio 2.66; 95% CI 1.10-6.70).
CONCLUSIONS: TE events after FD result from multiple factors, including age, aneurysm characteristics, aneurysm location, antiplatelet resistance, and procedural factors. In our cohort, we found the highest morbidity for patients with TE events presenting with large-vessel occlusion at the middle cerebral artery, and vertebrobasilar system.

OBJECTIVE: Anterior choroidal artery (AChA) aneurysms account for 2%-5% of all intracranial aneurysms. Treatment considerations include microsurgical clipping, flow diversion, or coiling with or without adjunctive devices. AChA aneurysms pose challenges in treatment due to the origination of the aneurysm from the origin or proximal segment of the AChA. The AChA is particularly susceptible to vasospasm and occlusion during treatment with devastating neurological deficits, including hemiparesis, hemianesthesia, lethargy, neglect, and hemianopia. In this study, the authors performed a meta-analysis to quantify the outcomes and complication rates across treatment modalities for AChA aneurysms and to identify risk factors reported in the literature.
METHODS: The authors performed a systematic review of AChA aneurysms treated with surgical clipping, endovascular coiling, or flow diversion and reported in the PubMed, Embase, Scopus, and Cochrane search databases. Single-arm meta-analyses of the selected outcomes were performed in RStudio.
RESULTS: Literature review yielded 25 studies that met the inclusion criteria. In total, 1627 patients were included in the analysis, with 554 males, 1009 females, and 64 unspecified. The rate of any complication in the full cohort was 11.6%, with a rate of ischemic complications of 5.5% and a favorable recovery rate of 90.3% of all patients treated. In total, 1064 patients underwent surgical clipping, 443 were treated with coiling, and 120 patients with flow diversion. In clipped patients, the rate of total surgical complications was 17.6%, with an ischemic complication rate of 9.4%. The rate of good functional recovery, defined on the basis of a Glasgow Outcome Scale score of 4-5 or modified Rankin Scale score of 0-2, was 88.0%, and complete obliteration was achieved in 84.5% of surgically clipped aneurysms. The complication rate in coiled patients was 10.3%, with an ischemic complication rate of 3.0%. Good functional recovery was achieved in 88.6% of coiled patients and complete aneurysm obliteration in 74.1%. Flow diversion resulted in a complication rate of 1.3%, with 0.7% rate of ischemic complications. Good functional recovery was achieved in 98.4% of patients and complete aneurysm obliteration in 79.0% in the flow diversion group. Aneurysm morphological features that impacted the complication rate were also identified to augment quantitative data and to help guide treatment selection for AChA aneurysms.
CONCLUSIONS: Flow diversion showed significantly lower total and ischemic complications and improved outcomes compared to clipping and coiling. There may be differences in outcomes between treatment types, especially when considering the varied patient presentations that guide treatment selection.

BACKGROUND: Endovascular options for the treatment of basilar apex aneurysms (BAAs) are heterogeneous, and evidence is limited to retrospective cohorts and case series. We seek to evaluate the efficacy and complications associated with various endovascular treatment methods of BAAs.
METHODS: Systematic review of PubMed, Embase, and Web of Science adhering to the PRISMA guidelines. Retrospective and prospective studies evaluating endovascular treatment of BAAs between January 2010 and July 2024 were included. Relevant information including occlusion rates, aneurysm recurrence, retreatment rates, and complications were subjected to meta-analysis.
RESULTS: Fifteen studies with 1,049 BAAs were included. The median aneurysm diameter was 8.5 mm (range 4.6-19.75), with a median follow-up of 33.7 months (range 6.0-117.6). Residual aneurysm filling occurred in 24% after primary coiling (95% CI=0.16-0.32), 25% after single stent-assisted coiling (s-SAC; 95% CI=0.04-0.46), 25% after Y-stenting (95% CI=0.12-0.37), and 23% after flow diverter stenting (FDS; 95% CI=0.11-0.35). Recurrence rates were high for primary coiling (27%, 95% CI=0.18-0.36) and s-SAC (19%, 95% CI=0.13-0.26), but significantly lower for Y-stenting (9%, 95% CI=0.03-0.15) and FDS (4%, 95% CI=-0.04-0.11). Retreatment rates were 19% for primary coiling (95% CI=0.12-0.26), 17% for s-SAC (95% CI=0.07-0.27), 5% for Y-stenting (95% CI=-0.03-0.12), and 13% for FDS (95% CI=-0.01-0.27). Meta-regression indicated larger aneurysms had higher complication rates (p=0.02). Thromboembolic events were most frequent with FDS and Y-stenting (12%).
CONCLUSIONS: Occlusion rates were similar across treatments, but recurrence rates were significantly lower after Y-stenting and FDS treatments compared to primary coiling, although they carried a higher number of thromboembolic complications.

Flow diversion for intracranial aneurysms emerged as an efficacious and durable treatment option over the last two decades. In a paradigm shift from intrasaccular aneurysm embolization to parent vessel remodeling as the mechanism of action, the proliferation of flow-diverting devices has enabled the treatment of many aneurysms previously considered untreatable. In this review, we review the history and development of flow diverters, highlight the pivotal clinical trials leading to their regulatory approval, review current devices including endoluminal and intrasaccular flow diverters, and discuss current and expanding indications for their use. Areas of clinical equipoise, including ruptured aneurysms and wide-neck bifurcation aneurysms, are summarized with a focus on flow diverters for these pathologies. Finally, we discuss future directions in flow diversion technology including bioresorbable flow diverters, transcriptomics and radiogenomics, and machine learning and artificial intelligence.

Despite advancements in treatment modalities such as flow diverters, the optimal management of posterior communicating artery (PComA) aneurysms remains uncertain. While PComA aneurysms treated with the Pipeline Embolization Device (PED) has been reported, the characteristics and progression of incomplete occluded aneurysms remain unclear. Therefore, our study aims to investigate the occlusion status and recurrence rates of PComA aneurysms treated with PED. A retrospective review of consecutive PComA aneurysm patients treated with PED was conducted between January 2015 and December 2020. Only patients with radiological follow-up were included. PComA aneurysms were categorized into incomplete occlusion and complete occlusion group. The primary outcomes included the characteristics of incomplete occlusion at the follow-up angiography. Among 121 PComA aneurysms treated with PED at our institution, 80 aneurysms were eligible in our study. During the follow-up period, 19 (23.8%) aneurysms demonstrated incomplete occlusion. Notably, there were no instances of recurrence among the 80 followed-up cases. Baseline characteristics of patients and aneurysms were comparable between the groups with complete and incomplete occlusion. However, the incomplete occlusion group showed a lower rate of assisted coils embolization (21.2% vs. 55.7%, P = 0.017) and shorter median operative time (91.0 vs. 145.5 min, P = 0.039). Differences in functional outcomes, complications, and PComA occlusion status between the groups were not significant. Multivariate analysis revealed the use of coils was associated with lower odds of incomplete PComA aneurysm occlusion (OR 0.01, 95% CI 0.001-0.12; P = 0.001), while aneurysm size was associated with higher odds of incomplete occlusion (OR 1.25, 95% CI 1.10-1.46; P = 0.002). The treatment of PED for PComA aneurysm demonstrated favorable outcomes, with an acceptable rate of incomplete occlusion and no instances of recurrence observed. However, further research is needed to explore the optimal procedural strategy for large-sized PComA aneurysms.

UNASSIGNED: Cerebral aneurysms located along the internal carotid artery at the origin of the ophthalmic artery can be treated through open surgery or endovascular technique. The former affords more certainty of aneurysm obliteration, while the latter poses less risk to vision. Flow diversion is an increasingly accepted treatment for side-wall carotid aneurysms, although location at the branch point of the ophthalmic artery is known to moderate occlusion outcomes.
UNASSIGNED: We present a case of a middle-aged female patient with a morphologically irregular 4-mm ophthalmic artery aneurysm (OphA) and a smaller superior hypophyseal artery (SHA) aneurysm whose successful and uncomplicated obliteration by flow diversion with adjunctive coiling was predicted via a balloon test occlusion (BTO). BTO was employed prior to stent placement to confirm a) ophthalmic artery distal collateralization with external carotid artery (ECA) branches and b) preserved arterial flow in the retina visualized via fundoscopy. At 1 year following angiography, the patient had no postoperative deficits and benefitted from complete occlusion of the OphA and SHA.
UNASSIGNED: OphAs constitute a complex surgical disease that is historically associated with high visual morbidity. We present a novel advanced endovascular technique of BTO followed by flow diversion with adjunctive coiling that successfully obliterated an OphA while preserving vision.

BACKGROUND: The Derivo 2 Heal Embolization Device (D2HED) is a novel flow diverter (FD) providing a fibrin-/heparin-based surface coating aiming at lower thrombogenicity. We evaluate periprocedural aspects and preliminary aneurysm occlusion efficacy for intracranial aneurysm treatment.
METHODS: Thirty-four D2HEDs deployments (34 aneurysms, 32 patients) between 04/2021 and 10/2023 were analyzed. All patients were under dual antiplatelet therapy (dAPT). Periprocedural details, adverse events, and follow-up (FU) imaging were reviewed by consultant-level neuroradiologists. Complication rates and aneurysm occlusion efficacy are compared with performance data of other FDs based on literature research.
RESULTS: Each intervention succeeded in the deployment of one D2HED. Significant and/or increased intraaneurysmal contrast stagnation immediately after D2HED deployment was seen in 73.5% of cases according to O\'Kelly-Marotta (OKM) grading scale. Clinically relevant early adverse events occurred in three patients: Among them two cases with fusiform aneurysms in the posterior circulation (ischemic events, early in-stent-thrombosis) and one patient (ischemic event) out of the majority of 31 treated internal carotid artery aneurysms (3,2%). Regarding mid-term FU (> 165 days), one aneurysm did not show progressive occlusion presumably caused by a prominent A1 segment arising from the terminal ICA aneurysm itself. Apart from that, mid-term complete / partial occlusion rates of 80% / 20% could be demonstrated.
CONCLUSIONS: Our case series - although suffering from restricted sample size - suggests a potential effectiveness of D2HED in managing intracranial aneurysms. Further studies with larger samples are warranted to quantify long-term occlusion efficacy and the impact of antithrombogenic surface coating on the necessary (d)APT.

Objective: Comparison of the results of stent-assisted coiling (SAC) with braided stents (BS), flow diverters (FD), and laser-cut stents (LCS) to determine the relative flow-diverting capacity of BS (Leo baby and Accero). Methods: Saccular intracranial aneurysms treated by SAC and FD-assisted coiling were retrospectively evaluated. Aneurysm occlusion, as graded per Raymond-Roy score, was categorized as either recanalization/stable residual filling (Group A; lacking a flow diversion effect) or stable/progressive occlusion (Group B with a \"flow diversion effect\"). Factors predicting the flow diversion effect were evaluated. Results: Of the 194 aneurysms included, LCS, BS, and FD were used in 70 (36.1%), 86 (44.3%), and 38 (19.6%) aneurysms, respectively. Aneurysms treated by FD were larger, had wider necks, and were located on larger parent arteries (p < 0.01, 0.02, and <0.01, respectively). The mean imaging follow-up duration was 24.5 months. There were 29 (14.9%) aneurysms in Group A and 165 (85.1%) in Group B. Among a spectrum of variables, including sex, age, aneurysm size, neck width, parent artery diameter, follow-up duration, and stent type, the positive predictors for stable/progressive aneurysm occlusion were aneurysm size and placement of an FD or BS (p < 0.01 and p < 0.01, respectively, and were positive predictors over LCS: ORs 6.34 (95% CI: 1.62-24.76) and 3.11 (95% CI: 1.20-8.07), respectively) in multivariate analysis. Conclusions: The placement of BS was a predictor of flow diversion over laser-cut stents. However, the flow diversion effect was approximately half that of FDs, suggesting that BS may only be considered to have some (partial) flow diversion effects.

This comprehensive review delves into the evolving field of neurointervention for intracranial aneurysms, exploring the critical adjunct of Dual Antiplatelet Therapy (DAPT) to endovascular coiling, stent-assisted coiling (SAC), flow-diversion stents, and flow-disruption (intrasaccular) devices. Despite growing evidence supporting the success of DAPT in reducing thromboembolic events, the lack of consensus on optimal regimens, doses, and duration is evident. Factors contributing to this variability include genetic polymorphisms affecting treatment response and ongoing debates regarding the clinical significance of hemorrhagic complications associated with DAPT. This review analyzes pre- and post-procedural antiplatelet usage across various interventions. The imperative lies in ongoing research to define optimal DAPT durations, ensuring a nuanced approach to the delicate balance between thrombosis and hemorrhage in intracranial aneurysm management.

This comprehensive review explores the multifaceted role of endothelial progenitor cells (EPCs) in vascular diseases, focusing on their involvement in the pathogenesis and their contributions to enhancing the efficacy of endovascular treatments for intracranial aneurysms (IAs). Initially discovered as CD34+ bone marrow-derived cells implicated in angiogenesis, EPCs have been linked to vascular repair, vasculogenesis, and angiogenic microenvironments. The origin and differentiation of EPCs have been subject to debate, challenging the conventional notion of bone marrow origin. Quantification methods, including CD34+ , CD133+ , and various assays, reveal the influence of factors, like age, gender, and comorbidities on EPC levels. Cellular mechanisms highlight the interplay between bone marrow and angiogenic microenvironments, involving growth factors, matrix metalloproteinases, and signaling pathways, such as phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK). In the context of the pathogenesis of IAs, EPCs play a role in maintaining vascular integrity by replacing injured and dysfunctional endothelial cells. Recent research has also suggested the therapeutic potential of EPCs after coil embolization and flow diversion, and this has led the development of device surface modifications aimed to enhance endothelialization. The comprehensive insights underscore the importance of further research on EPCs as both therapeutic targets and biomarkers in IAs.