Ognard, Julien

ABSTRACT Endoluminal flow diverters are increasingly used to treat cerebral aneurysms. Despite good aneurysm occlusion efficacy, delayed ischemic complications due to side branch or perforator occlusion remain a serious concern. However, the mechanisms leading to side branch occlusion are poorly understood. To investigate these mechanisms, a combination of animal and computational models was utilized. Flow diverters were deployed in four rabbit superior mesenteric artery (SMA) and studied with computational fluid dynamics (CFD) and a previously developed fibrin dynamics model. Subject‐specific vascular models were reconstructed from 3D rotational angiography images and flow conditions were derived from Doppler ultrasound velocity measurements. Flow diverting devices were virtually deployed within the vascular models under guidance from angiography images. Coupled flow and fibrin production, transport, and adhesion simulations were carried out and the effects of fibrin accumulation at the origin of jailed side branches after flow diverter implantation were analyzed. The results of the computational models suggest significant fibrin accumulation across the struts of all flow diverting devices jailing side branches. Larger accumulation was observed at the more distal branches. However, minor flow alterations were produced which were not detectable in angiography sequences. These results were in agreement with experimental observations. On the other hand, fibrin accumulation alone did not explain complete side branch occlusions, which are likely the result of the interaction between initial fibrin accumulation and subsequent cell migration from the peripheral parent artery.

Background: Pulsatile tinnitus (PT) is frequently caused by venous sinus stenosis and may be associated with idiopathic intracranial hypertension (IIH). Venous sinus stenting (VSS) directly addresses venous outflow obstruction and has emerged as a therapeutic option; however, outcome data remain heterogeneous. We performed an updated systematic review and meta-analysis to evaluate the efficacy and durability of VSS for PT and to compare outcomes between IIH-associated and isolated PT. Methods: MEDLINE, Scopus, and Web of Science were searched from inception through December 2025 following PRISMA guidelines. Clinical studies reporting PT outcomes after VSS were included. Random-effects meta-analyses of proportions were conducted to estimate pooled rates of overall improvement, complete resolution, and recurrence. Prespecified subgroup analyses compared IIH versus isolated PT. Results: Thirty-two studies comprising 850 patients were included (641 with IIH; 209 with isolated PT). Venous sinus stenosis accounted for 90.3% of treated etiologies. The pooled rate of overall PT improvement was 89.8% (95% CI, 85.5-92.9). Complete resolution occurred in 87.1% (95% CI, 82.5-90.6). Recurrence at last follow-up was 10.9% (95% CI, 8.3-14.2). Improvement and complete resolution rates did not differ significantly between IIH and isolated PT. Recurrence was higher in IIH (12.0%) than in isolated PT (5.7%), without reaching statistical significance. Conclusions: VSS is associated with high rates of PT improvement and complete resolution with low recurrence. Recurrence trends appear higher in IIH, suggesting underlying pathophysiology may influence durability.

Background Animal models are essential for evaluating endovascular device safety and efficacy. Rats offer advantages, such as genetic manipulability, lower cost, and shorter healing and breeding cycles, compared to large animals. These features support studying aneurysm healing mechanisms and enable high-throughput testing. We developed an optimal rat aneurysm model for device evaluation. Methods Saccular aneurysms were created at the origins of the left renal artery (LRA) with acetylsalicylic acid (ASA) (LRA/ASA group, n = 7); the right common iliac artery (RCIA) with ASA alone (RCIA/ASA group, n = 6) or ASA plus clopidogrel (CLP) (RCIA/ASA + CLP group, n = 7); and the left common iliac artery (LCIA) with ASA + CLP (LCIA/ASA + CLP group, n = 7). The origins of these arteries were surgically exposed. During temporary ligation of the vessel origin, the vessel was bisected and endoluminal elastase was incubated in the proximal stump for 10 min, followed by release of the proximal ligation and permanent ligation of the stump. Angiographical and histological analysis were performed 4 weeks post-procedure. Results Follow-up digital subtraction angiography revealed mean ± standard deviation aneurysm height/neck dimensions of 1.2 ± 0.4/1.2 ± 0.1, 2.9/3.1, 2.3 ± 0.6/1.9 ± 0.3, and 2.1 ± 0.6/2.0 ± 0.4 mm for the LRA/ASA, RCIA/ASA, RCIA/ASA + CLP, and LCIA/ASA + CLP groups, respectively. The survival rate was 29%, 17%, 71%, and 86% in the LRA/ASA, RCIA/ASA, RCIA/ASA + CLP, and LCIA/ASA + CLP groups, respectively. Histopathological analysis of these aneurysms confirmed the absence of the internal elastic lamina and revealed aneurysmal changes in the arterial wall, resembling the pathological findings observed in human aneurysm specimens. Conclusions Common iliac aneurysm models with ASA + CLP can be used to evaluate the safety and efficacy of endovascular devices.

Introduction Spontaneous intracranial hypotension (SIH) has been underdiagnosed, primarily due to limited clinical recognition and diagnostic capabilities. Recent improvements in diagnostic awareness and the implementation of advanced imaging techniques, notably targeted myelography and photon‐counting computed tomography (PCCT), have improved detection of cerebrospinal fluid‐venous fistulas (CSFVFs). We provide an updated SIH incidence within a defined U.S. County and quantify the proportional contribution of CSFVFs in this evolving diagnostic context. Methods We performed a retrospective, population‑based cohort study of adults evaluated for SIH from January 2019 through August 2025 at a quaternary referral center. Standard evaluation included brain MRI, whole‑spine MRI screening for spontaneous spinal CSF leaks (SLEC), and targeted myelography (lateral‑decubitus digital subtraction or dynamic CT/PCCT when available). Incident SIH was defined as the first imaging‑confirmed leak per patient. Incidence per 100,000 adult person‑years used adult population denominators with exact Poisson 95% CIs. Results We identified 33 incident SIH cases; 22/33 (66.7%) were CSFVF. Overall SIH incidence was 4.02 (95% CI 2.77‐5.65) per 100,000 person‑years; CSFVF‑specific incidence was 2.68 (95% CI 1.68‐4.06), 2.35 in women (95% CI 1.25‐4.02) and 1.50 in men (95% CI 0.65‐2.96). Significant upward trends were observed in annual incidence rates for SIH (Incidence Rate Ratio [IRR]: 1.23, 95% CI: 1.02‐1.48, p = 0.027) and specifically for CSFVFs (IRR: 1.29, 95% CI: 1.03‐1.63, p = 0.029). The symptom duration before diagnosis had a median of 4 months and appears to be shortening over time: 7 months in 2019‐2021 versus 4 months in 2022‐2025, consistent with faster recognition and targeted imaging. Conclusion The incidence of SIH, particularly due to CSFVFs, has increased significantly, likely attributable to improved clinical recognition and advanced imaging techniques rather than a true epidemiological shift. This highlights an urgent clinical message: maintain a high index of suspicion, image accordingly, and treat promptly. image image

Background/Objectives: Idiopathic intracranial hypertension (IIH) often features dural venous sinus stenosis; venous sinus stenting (VSS) improves venous outflow and intracranial pressure, but most stents are off-label, and few are engineered for intracranial venous anatomy. The aim was to synthesize animal models relevant to IIH/VSS, catalogue stents used clinically for VSS and summarize corresponding animal data, appraise current preclinical VSS research, and propose a pragmatic preclinical evaluation framework. Methods: We performed a targeted search (PubMed, Web of Science, Scopus; through to May 2025), dual-screened the records in Nested Knowledge, and extracted the model/device characteristics and outcomes as per the predefined criteria. Results: We identified 65 clinical VSS studies; most were retrospective and used off-label carotid/peripheral/biliary stents (Precise, Zilver, and Wallstent were the most frequent). Recent dedicated systems (River, BosStent) have limited animal evidence; VIVA has GLP porcine venous peripheral data demonstrating its patency, structural integrity, and benign healing outcomes. Rodent models reproduce obesity/androgen drivers with modest, sustained ICP elevation; large animal models show the technical feasibility of in sinus implantation, but no chronic focal venous stenosis model fully mirrors the IIH condition. Conclusions: Despite broad clinical uptake, the translational underpinnings of VSS in IIH remain incomplete: most devices lack intracranial venous-specific preclinical validation, and there is no existing animal model that recapitulates both IIH biology and focal sinus stenosis.

Background Guide catheter (GC) placement, whether distal or proximal, may influence the efficacy and safety of mechanical thrombectomy (MT) for acute ischemic stroke (AIS) due to large vessel occlusion (LVO). However, definitions of placement and procedural strategies vary across studies, limiting clarity. Methods We systematically searched PubMed, Embase, Scopus, and Web of Science from inception to September 1, 2024. Comparative studies of adult patients with anterior circulation AIS-LVO undergoing MT that reported GC placement were included. Both balloon GCs (BGCs) and non-BGCs were eligible. Data were pooled using random-effects models in R. Outcomes included functional independence (modified Rankin Scale 0–2 at 90 days), successful reperfusion (modified thrombolysis in cerebral infarction ≥2b or expanded thrombolysis in cerebral infarction ≥2c), first-pass recanalization (FPR), mortality, puncture-to-recanalization (PTR) time, and complications. Subgroup analyses were performed by thrombectomy technique and catheter type. Results Seven retrospective studies comprising 2148 patients (1042 proximal, 1106 distal) were analyzed. Distal placement was associated with higher rates of functional independence (risk ratio (RR): 1.25, 95% confidence interval (CI): 1.10–1.42), successful reperfusion (RR: 1.13, 95% CI: 1.04–1.22), and FPR (RR: 1.35, 95% CI: 1.15–1.58), as well as lower 90-day mortality (RR: 0.52, 95% CI: 0.28–0.82). PTR time was shorter with distal placement (mean difference: −7.7 min, 95% CI: −10.8 to −4.6). No significant differences were observed for symptomatic intracranial hemorrhage (RR: 0.96, 95% CI: 0.55–1.65) or emboli to new territory (RR: 0.84, 95% CI: 0.28–2.52). Benefits were consistent across both BGCs and non-BGCs. Heterogeneity existed in outcome definitions and techniques, and publication bias could not be excluded. Conclusions Distal GC placement is associated with improved reperfusion, efficiency, and functional outcomes in MT for anterior circulation AIS-LVO, without increased complications. Given the retrospective nature of included studies, anatomic confounding, and inconsistent outcome definitions, findings should be considered preliminary. Multicenter trials are needed to confirm whether catheter position independently predicts MT outcomes.