Baccin, Carlos E.

Introduction Although Valsalva maneuvers and strenuous exercise are commonly discouraged in patients with intracranial aneurysms (IAs), the cerebrovascular stress they induce remains poorly characterized. To our knowledge, no prior review has systematically quantified their effects on hemodynamic surrogates of rupture risk. Objective To characterize the acute intracranial hemodynamic effects of strenuous physical activity and Valsalva maneuvers in individuals with and without IAs. Methods We searched PubMed, Embase, Scopus, Web of Science, and Cochrane (February 2025; PROSPERO ID: CRD42025637608) following PRISMA. Eligible studies reported acute changes in SBP, ICP, central venous pressure (CVP), cerebrovascular transmural pressure (CVTMP), middle cerebral artery (MCA) velocity, or CFD‐derived parameters (wall shear stress [WSS], oscillatory shear index [OSI], relative residence time [RRT]) in response to physical exertion or Valsalva. Populations included individuals with or without IAs. Acute neurological symptoms were also reviewed. Results From 2,859 records, 14 studies met inclusion criteria. Eight studies assessed real‐time hemodynamic responses during exercise (91 participants without IAs). Three studies (n=39) showed that resistance exercise increased SBP (mean Δ+21.8 mmHg). Two studies (n=22) showed significant MAP elevation (mean Δ+24.7 mmHg). When combined with a Valsalva maneuver, SBP increased further (mean Δ+26 mmHg; range 20–30). Three studies (n=38) evaluating isolated Valsalva identified significant ICP elevation (mean Δ+15 mmHg; range 5.7–24.3), primarily driven by CVP increases (mean Δ+52.0 mmHg; range 39–56). Breath‐holding during exertion reduced MCA velocity (mean Δ–11.6 cm/s), while continuous ventilation preserved more stable flow. In seven patients, resistance exercise without Valsalva increased CVTMP by 24.5%. In contrast, Valsalva alone raised ICP and CVP without increasing SBP, yielding a CVTMP 11% lower than during exercise alone. These paired observations suggest that Valsalva may transiently offset exercise‐induced transmural stress by raising ICP alongside SBP. However, this effect may be time‐limited and reverse during early recovery—when SBP remains elevated as ICP quickly normalizes—potentially producing a CVTMP rebound above exercise‐only levels. Six CFD studies (11 aneurysms; diameter 6.3–23 mm; 2 ruptured) reported exercise‐related increases in time‐averaged WSS (mean +21.7%, range –4.4% to +50%) and peak WSS (mean +382.3%, range +100% to +628%). Exercise‐induced changes in heart rate and flow pulsatility led to complex redistributions of intra‐aneurysmal WSS, potentially exposing the aneurysmal wall to focal mechanical stress. Conclusion Resistance exercise, especially with breath‐holding, provokes dynamic, time‐sensitive cerebrovascular stress. Valsalva maneuver may transiently lower CVTMP during effort, yet its release with lingering SBP elevation can precipitate delayed transmural pressure surges. The proposed biphasic effect of Valsalva offers a novel conceptual framework for prospective. Our findings underscore the need to define safe, individualized activity thresholds for patients with IAs with patient‐specific validation integrating concurrent physiology and CFD to reduce the risk of IA growth and rupture.

Introduction The risk of aneurysmal subarachnoid hemorrhage (aSAH) during exercise is not well quantified. We assessed temporal clustering of aSAH around physical exertion and around Valsalva‐like activities (defecation or urination). Objectives To estimate the proportion of aSAH cases temporally linked to strenuous activities using reported exposure‐to‐onset window uwing within‐person odds of rupture from case‐crossover studies. Methods We searched PubMed/MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Library from inception through January 2025, and hand‐searched reference lists (PRISMA‐aligned; PROSPERO CRD42025637608). Eligible studies reported the activity at aSAH onset or within a defined pre‐onset window. Exposures were analyzed separately (exertion; defecation/urination). Primary proportional estimates used each study's own exposure‐to‐onset window as reported. To improve comparability, subgroup analysis was performed with only a prespecified subset pooled consecutive case series that explicitly used a ≤2‐hour window between the index activity and aSAH. Within‐person odds ratios (ORs) were abstracted from case‐crossover studies. Risk of bias for observational exposure studies was assessed with ROBINS‐E by two independent reviewers. Results Sixteen studies (published 1980–2022) from 10 countries were included with 5,815 cases of aSAH (mean age 55 years; 60.6% female). Designs comprised 10 case series, 3 case reports, 2 case‐crossover studies, and 1 case‐control study. Activity‐at‐onset was recorded for 4,219/5,815 (72.6%); among these 4,219 patients, mean age was 52.7 years. Using each study's reported window, 308/4,219 (7.3%) aSAH occurred during or within the study‐defined window after physical exertion, and 387/4,219 (9.2%) during/within the window after defecation or urination 695/4,219 (16.5%) were temporally linked to either exposure. In the subset of 10 consecutive case series restricted to ≤2 hours, 275 (5.4%) were linked to exertion and 385 (7.6%) to defecation/urination (combined 660; 13.0%). Study‐specific proportions ranged from 0.8–21.3% for exertion and 2.0–15.4% for defecation/urination. Two case‐crossover studies reported higher within‐person odds of rupture after moderate‐to‐vigorous exertion (OR 2.4–2.7). Temporal clustering of aSAH around exertion or straining was observed in 13–17% of cases, depending on dataset and inclusion criteria. Conclusions Although this relatively high rate of temporal association between aSAH and exercise might suggest an increased risk of aneurysm rupture during strenuous activity, variable definitions and unstated exposure‐to‐onset windows do not permit causal inference. Prospective or registry‐embedded case‐crossover studies using standardized exposure definitions (intensity, duration) and objective exposure capture are needed to refine immediate‐risk estimates and identify patient‐level susceptibility modifiers.

BACKGROUND AND IMPORTANCE: Basilar artery fenestration aneurysms (BAFAs) present significant clinical challenges because of their high rupture risk and complex anatomy. Comprehensive management strategies are required, including thorough vascular assessment and post-treatment surveillance. Integration of complementary analyses such as computational fluid dynamics (CFD) holds promise in facilitating preoperative planning for these intricate lesions. CLINICAL PRESENTATION: A 60-year-old female was diagnosed with a BAFA during evaluation for headaches. Digital subtraction angiography revealed the aneurysm projecting posteriorly with a neck predominantly based on the right limb of the fenestration. After initial treatment with a pipeline embolization device, the aneurysm remained patent, requiring further treatment. A secondary approach with stent-assisted loose-packing coil embolization was then performed, resulting in complete occlusion of the aneurysm. Analysis of pretreatment 3-dimensional rotational angiogram images with CFD provided critical hemodynamic insights. It identified that 38.89% of the aneurysm area was exposed to low wall shear stress (WSS) and 11.5% was exposed to high WSS, indicating a high rupture risk profile with significant areas of both low and high WSS. In addition, low WSS was observed in regions corresponding to daughter sacs, suggesting a higher rupture risk. Streamline analysis indicated increased inflow through the right vertebral artery and the right limb of the fenestration, supporting the initial angiographic impression and guiding the choice of therapeutic strategy. CONCLUSION: This is the first study to analyze the morphology and pretreatment hemodynamics of a BAFA using CFD, illustrating the potential for future development of individualized therapeutic approach–based CFD in complex aneurysms.

Background: We present five patients with remodeling of the adult circle of Willis in response to flow diverter stents (FDSs) at the anterior communicating artery (AComA) and the posterior communicating artery (PComA). The observed changes provide a paradigm of how flow change can institute anatomic changes in the adult circle of Willis vasculature. Case Description: In the first two cases, after placement of the FDS covering the AComA, there was an increase in size and flow of the contralateral A1-anterior cerebral artery which had previously been hypoplastic. In one of the cases, this led to the filling of the aneurysm and required placement of coils within the lesion which was curative. In case three, the FDS effect led to asymptomatic occlusion of the PComA and associated aneurysm without change of the ipsilateral P1-segement of posterior-cerebral-artery (P1-PCA) caliber. In the fourth case, the FDS covering an aneurysm with a fetal PCA arising from its neck resulted in significant reduction of the aneurysm size, persistent flow and caliber of the fetal PCA, and the hypoplastic ipsilateral P1-PCA. Finally, in the fifth case, after FDS occlusion of the PComA and aneurysm there was increasement in diameter of the ipsilateral P1-PCA that was previously hypoplastic. Conclusion: The use of FDS can affect vessels covered by the device and other arteries of the circle of Willis adjacent to the FDS. The phenomena illustrated in the hypoplastic branches appear to be a compensatory response to the hemodynamic changes induced by the divertor and to the altered flow in the circle of Willis.

Embolic coiling is one of the most effective treatments for cerebral aneurysms (CAs), largely due to the hemodynamic modifications that the treatment effects in the aneurysmal environment. However, coiling can have very different hemodynamic outcomes in aneurysms with different geometries. Previous work in the field of biofluid mechanics has demonstrated on a general level that geometry is a driving factor behind aneurysmal hemodynamics. The goal of this study was to relate two specific geometric factors that describe CAs (i.e., dome size (DS) and parent-vessel contact-angle (PV-CA)) and one factor that describes treatment (i.e., coil packing density (PD)) to three clinically relevant hemodynamic responses (i.e., aneurysmal root-mean-square velocity (Vrms), aneurysmal wall shear stress (WSS), and cross-neck flow (CNF)). Idealized models of basilar tip aneurysms were created in both virtual and physical forms to satisfy two-level multifactorial experimental designs. Steady and pulsatile flow hemodynamics were then evaluated in the virtual models using computational fluid dynamics (CFD) (before and after virtual treatment with finite element (FE) embolic coil models), and hemodynamics were also evaluated in the physical models using particle image velocimetry (PIV) (before and after treatment with actual embolic coils). Results showed that among the factors considered, PD made the greatest contributions to effects on hemodynamic responses in and around the aneurysmal sac (i.e., Vrms and WSS), while DS made the greatest contributions to effects on hemodynamics at the neck (i.e., CNF). Results also showed that while a geometric factor (e.g., PV-CA) may play a relatively minor role in dictating hemodynamics in the untreated case, the same factor can play a much greater role after coiling. We consider the significance of these findings in the context of aneurysmal recurrence and rupture, and explore potential roles for the proposed methods in endovascular treatment planning.