De Novo Aneurysm Formation After Internal Carotid Artery Sacrifice: Impact of Aneurysmal Versus Non-Aneurysmal Etiology

De Novo Aneurysm Formation After Internal Carotid Artery Sacrifice: Impact of Aneurysmal Versus Non-Aneurysmal Etiology | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article De Novo Aneurysm Formation After Internal Carotid Artery Sacrifice: Impact of Aneurysmal Versus Non-Aneurysmal Etiology Jun Sang Yoo, Mi Hyeon Kim, Jong-Tae Yoon, Jae Ho Lee, Boseong Kwon, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7421358/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Nov, 2025 Read the published version in Clinical Neuroradiology → Version 1 posted You are reading this latest preprint version Abstract Background Endovascular trapping of the internal carotid artery (ICA) remains a definitive treatment for both aneurysmal and non-aneurysmal conditions when vessel-preserving strategies are not feasible. However, increasing attention has been directed toward the risk of de novo aneurysm formation following ICA sacrifice, presumably due to hemodynamic alterations within the Circle of Willis. This study aimed to evaluate the incidence and potential risk factors for de novo aneurysm development after ICA trapping, particularly focusing on differences based on the underlying pathology, aneurysmal versus non-aneurysmal. Methods A retrospective, single-center study was conducted on patients who underwent unilateral endovascular ICA trapping between 2003 and 2023, with a minimum of one year of angiographic follow-up. Patients were categorized into the aneurysm-trapping (AT) or non-aneurysm-trapping (NT) group according to the underlying indication for ICA sacrifice. Clinical, angiographic, and procedural data were reviewed to evaluate the development of de novo aneurysms or the progression of pre-existing lesions. Results Among the 47 included patients (37 and 10 in the AT and NT groups, respectively), de novo aneurysm formation or significant growth of pre-existing aneurysms was observed exclusively in the AT group (10/37, 27.0%), with no such events in the NT group (0/10), although the difference did not reach statistical significance (p = 0.064). Most newly developed aneurysms (60%) arose at the anterior communicating artery (ACoA), predominantly in patients with well-developed ACoA collateral flow. Most lesions appeared within two years after ICA trapping. Additional treatment was required in two patients due to progressive enlargement of pre-existing aneurysms. Conclusion De novo aneurysm formation following ICA trapping appears to occur exclusively in patients with an underlying aneurysmal etiology, particularly at sites of hemodynamic stress such as the ACoA. Close imaging surveillance is recommended during the first two years post-trapping, especially in patients with robust collateral circulation or pre-existing aneurysms. Endovascular trapping ICA sacrifice De novo aneurysm Neurointervention Coil embolization Figures Figure 1 Figure 2 Figure 3 INTRODUCTION Endovascular internal carotid artery (ICA) trapping has historically been a widely used technique, particularly in cases where conventional reconstructive options such as clipping, coiling, or stent placement are not feasible. In recent years, the advent of flow diversion therapy has transformed the treatment paradigm for many complex aneurysms, enabling vessel-preserving strategies even in anatomically challenging lesions. 1 However, despite these advances, certain clinical scenarios still require ICA trapping as a definitive treatment for aneurysmal disease, 2 , 3 particularly when flow diversion is contraindicated, has failed, or is technically unfeasible due to anatomical or hemodynamic factors. Furthermore, ICA sacrifice remains indispensable in the management of various non-aneurysmal pathologies, such as traumatic pseudoaneurysms, arterial ruptures, dissections, or carotid-cavernous fistulas, where vessel preservation is either not a priority or not possible. In such cases, endovascular ICA trapping, either alone or in conjunction with extracranial-intracranial (EC-IC) bypass surgery, continues to serve as a valuable and effective therapeutic option, particularly when adequate collateral flow is confirmed. 2 However, one of the known drawbacks of this approach is the hemodynamic alteration that follows ICA sacrifice. Flow redistribution within the circle of Willis (COW) inevitably leads to increased hemodynamic stress along collateral channels, particularly the anterior communicating artery (ACoA) and posterior communicating artery (PCoA), which are called upon to compensate for the loss of antegrade ICA flow. 4 , 5 This shift in hemodynamic burden has been associated with de novo aneurysm formation, often at sites that were previously unaffected. While this phenomenon is well acknowledged, current evidence is largely limited to small case series and anecdotal reports, highlighting the need for more comprehensive long-term data. 6 – 10 At our institution, endovascular ICA trapping has been performed over an extended period, with many patients undergoing long-term imaging surveillance. Based on this clinical experience, a single-center retrospective analysis was conducted with the following objectives: (1) to determine the incidence, location, size, and rupture status of de novo aneurysms occurring after ICA trapping, and (2) to investigate whether the underlying indication for ICA trapping, aneurysmal versus non-aneurysmal, affects the risk or pattern of de novo aneurysm development. MATERIALS AND METHODS Patients Patients who underwent unilateral endovascular ICA trapping at our institution were retrospectively identified from the neurointerventional procedure database, regardless of the underlying indication. The study was conducted between 2003, when the picture archiving and communication system began storing angiographic imaging data, and 2023. Patients were included if they had available imaging follow-up of at least one year after ICA trapping using any vascular imaging modality, including computed tomography (CT) angiography, magnetic resonance (MR) angiography (with or without contrast enhancement), or cerebral digital subtraction angiography (DSA). Patients without adequate imaging follow-up during this period were excluded (Fig. 1 ). Demographic and clinical data, including aneurysm risk factors such as hypertension, smoking, and family history of aneurysm, were retrospectively collected from a registry using electronic medical record data. The primary indication for ICA trapping was reviewed for each patient, and individuals were categorized into two groups based on the underlying etiology. Patients who underwent ICA trapping primarily for the treatment of aneurysmal lesions were classified as the ‘aneurysm-trapping (AT) group.’ In contrast, those who underwent ICA trapping for non-aneurysmal causes were assigned to the ‘non-aneurysm-trapping (NT) group.’ The NT group included cases of traumatic ICA injury (e.g., dissection, pseudoaneurysm, or rupture), iatrogenic ICA injury (e.g., cavernous ICA perforation during transsphenoidal surgery), carotid blowout syndrome associated with head and neck malignancy, and carotid-cavernous fistulas, representing a spectrum of non-aneurysmal conditions. This study was conducted with approval from the Institutional Review Board (IRB) of our institution, and the requirement for informed consent was waived owing to the retrospective nature of the study (IRB number: 2025 − 0697). Neurovascular imaging This retrospective imaging analysis utilized data collected over a 20-year period from 2003 to 2025. Due to the diversity of MR angiography, CT angiography, and DSA equipment models and image acquisition parameters used during this period, a comprehensive listing of all imaging equipment was impractical. Therefore, representative imaging equipment and parameters commonly used during this period are summarized below. MR imaging was performed using 3.0T MRI systems, including Ingenia and Achieva (Philips Healthcare, Best, Netherlands), with repetition time (TR)/echo time (TE) = 25/3.5 ms, flip angle (FA) = 20°, field of view (FOV) = 200 × 250 × 100 mm, matrix = 880 × 880, and slice thickness = 1 mm; and MAGNETOM Vida (Siemens Healthineers, Erlangen, Germany) with TR/TE = 21.3/3.7 ms, FA = 20°, FOV = 200 × 220 mm, matrix = 648 × 594, and slice thickness = 0.40 mm. CT angiography was performed using a 16-slice CT scanner (Lightspeed Ultra, GE Healthcare, Waukesha, WI, USA) with tube voltage = 120 kV, tube current = 400 mA, exposure time = 0.50 s, mAs = 200, display FOV (DFOV) = 210 mm, and slice thickness = 0.63 mm. Additionally, 128-slice CT scanners (SOMATOM Definition Flash, Siemens Healthineers, Forchheim, Germany, and SOMATOM Definition Edge, Siemens Healthineers, Erlangen, Germany) were used with tube voltage = 120 kV, tube current = 300–400 mA, exposure time = 0.50 s, mAs = 200, DFOV = 200 mm, and slice thickness = 1 mm. Conventional angiography and embolization were performed using a biplane angiography machine (Artis zee; Siemens Healthineers, Forchheim, Germany). Pre- or intra-procedural angiography analysis In the AT group, pre-trapping angiography was used to document the maximum size and location of the index aneurysm, as well as the presence, size, and location of any additional aneurysms in other arterial segments. Collateral status during test balloon occlusion was assessed by evaluating the presence and caliber of ACoA and PCoA. The caliber of these communicating arteries was categorized into three grades reflecting collateral flow capacity: grade 0 for absent or rudimentary channels, grade 1 for partially developed but insufficient channels, and grade 2 for well-developed and hemodynamically competent channels. In selected cases, EC-IC bypass surgery was performed when collateral circulation was deemed insufficient based on test balloon occlusion results. Brain perfusion single photon emission CT imaging was additionally used to support the decision for bypass surgery in elective cases; however, it was omitted in emergent settings where trapping was urgently required. Follow-up angiography analysis Vascular imaging was routinely performed on post-procedure day 1 following ICA trapping. For subsequent follow-up, intracranial angiographic studies, primarily time-of-flight MR angiography (TOF-MRA), and occasionally contrast-enhanced MR angiography or CT angiography (CTA), were conducted, depending on the embolization method and clinical context. TOF-MRA was preferred in most cases, particularly those treated with platinum embolization coils, whereas CTA was more commonly used in cases involving detachable balloons. Follow-up imaging focused on assessing the completeness of trapping and evaluating the COW, with particular attention to changes in collateral flow and the development of new vascular lesions. Specifically, the presence of de novo aneurysms, defined as any newly identified arterial bulging lesion not visible on pre-trapping baseline imaging, was assessed. Interval growth of pre-existing aneurysms, if any, was also documented. In patients with pre-existing aneurysms, interval growth was determined based on expert consensus. De novo aneurysm formation and interval growth of pre-existing aneurysm were considered present when two board-certified neurointerventional radiologists independently agreed that a visible increase in aneurysm size had occurred on follow-up imaging, compared with baseline. In cases of disagreement, a senior adjudicator reviewed the images and made the final determination. Lesions with poorly defined margins or insufficient image quality were excluded from the analysis to minimize interpretation bias. For all aneurysmal events, the location and time of detection during follow-up were recorded. Collateral circulation status was analyzed based on balloon occlusion testing prior to trapping, with grading of the ACoA and PCoA according to their size and flow adequacy. This was also recorded when EC-IC bypass was performed. Statistical analysis A comprehensive statistical comparison was performed to evaluate patient demographics, clinical data including risk factors, and angiographic characteristics. Comparisons were performed between the AT (n = 37) and NT (n = 10) groups based on the underlying etiology requiring ICA trapping, followed by subgroup comparison within the AT group between those with and without de novo aneurysm (n = 37). Student’s t-tests were used for continuous variables, and chi-square tests were applied to categorical variables. Continuous data are presented as means with standard deviations, and categorical data are expressed as frequencies and percentages. All statistical analyses were performed using SPSS version 19.0 (IBM Corp., Armonk, NY, USA), and a p-value < 0.05 was considered statistically significant. RESULTS As illustrated in Fig. 1 , a total of 84 patients underwent endovascular ICA trapping at our institution between January 2003 and June 2023. Of these, 37 patients were excluded due to the absence of angiographic follow-up for at least one year, leaving 47 patients eligible for analysis. Among the included cohort, 37 patients (78.7%) were classified into the AT group and 10 patients (21.3%) into the NT group, based on the underlying etiology necessitating ICA trapping. Comparison between AT group and NT group As shown in Table 1 , the AT and NT groups had a well-balanced age distribution but showed a significant difference in sex, with a higher proportion of female patients in the AT group (78.4% vs. 20.0%, p = 0.001). No statistically significant difference in aneurysm risk factors were observed between the two groups. Additionally, the frequency of EC-IC bypass surgery and aneurysm laterality did not differ notably. The interval from ICA trapping to the final angiographic imaging follow-up was longer in the AT group than in the NT group (67.9 ± 43.1 months vs. 35.2 ± 30.3 months, p = 0.013). Comparison of COW collaterals showed similar grading of the ACoA and PCoA between the two groups. Table 1 Patient characteristics between the aneurysm-trapping and non-aneurysm-trapping groups following ICA trapping Aneurysm-trapping group (n = 37) Non-aneurysm-trapping group (n = 10) p Demographic Sex, male (%) 8 (21.6) 8 (80) 0.001 Age (years) 53.4 ± 14.8 51.4 ± 19.5 0.918 Aneurysm risk factor Hypertension (%) 13 (35.1) 4 (40) 0.776 History of smoking (%) 6 (16.2) 3 (30) 0.326 Family history of aneurysm (%) 1 (2.7) 0 (0) 0.721 Aneurysm formation 10 (27) 0 (0) 0.064 Location Size Side (right) (%) 23 (62.2) 5 (50) 0.487 s/p Bypass OP (EC-IC) (%) 8 (21.6) 3 (30) 0.579 Patency of ACoA (%) 20 (54.1) 5 (50) 0.820 Patency of PCoA (%) 20 (54.1) 4 (40) 0.430 Data are presented as mean ± standard deviation, median (IQR), or number (%). EC-IC, extracranial-intracrania; OP, operation; ACoA, anterior communicating artery; PCoA, posterior communicating artery. Table 2 Comparison between groups with and without de novo aneurysm formation De novo aneurysm (+) (n = 10) De novo aneurysm (-) (n = 27) p Demographic Sex, male (%) 3 (30) 5 (18.5) 0.451 Age (years) 48.3 ± 17.5 55.3 ± 13.6 0.292 Aneurysm risk factor Hypertension (%) 3 (30) 10 (37.0) 0.690 History of smoking (%) 3 (30) 3 (11.1) 0.166 Family history of aneurysm (%) 0 (0) 1 (3.7) 0.537 Interval period (months) (until incidence or last F/U) 121.7 ± 137.9 144.2 ± 92.4 0.642 Vascular features Side (right) (%) 5 (50) 18 (66.7) 0.353 s/p Bypass OP (EC-IC) (%) 1 (10) 7 (25.9) 0.296 Patency of ACoA (%) 8 (80) 12 (44.4) 0.054 Patency of PCoA (%) 4 (40) 16 (59.3) 0.297 Data are presented as mean ± standard deviation, median (IQR), or number (%). EC-IC, extracranial-intracranial; OP, operation; ACoA, anterior communicating artery; PCoA, posterior communicating artery. De-novo aneurysm formation (n = 9, Fig. 2 ) or significant pre-existing aneurysm growth (n = 1, Fig. 3 ) was observed in 10 patients, all within the AT group. However, the difference did not reach statistical significance due to small number of patients in the NT group (10/27 vs. 0/10, p = 0.064). When comparing patients who developed new aneurysms or exhibited pre-existing aneurysm growth (n = 10) with those who did not (n = 27) within the AT group (n = 37), no significant differences were observed in age, sex, aneurysm laterality, aneurysm risk factors, or follow up interval days. Regarding COW collateral status, a higher proportion of patients with well-developed ACoA collateral was identified in the de novo aneurysm group, although the difference did not reach statistical significance (80% vs. 44.4%, p = 0.054) All 10 patients who developed a new aneurysm (Fig. 2 ) or exhibited enlargement of a pre-existing aneurysm (Fig. 3 ) during the follow-up period were individually reviewed, and details are summarized in Table 3 . Among the 10 new aneurysms identified, six were located in the ACoA complex, two in the ICA (one de novo aneurysm and one interval growth of preexisting aneurysm), one in the PCA, and one in the SCA. Regarding the interval to aneurysm formation, six patients were identified within 19.7 months, whereas three were detected late due to delayed angiographic follow up. The progression and treatment requirements of all 10 aneurysms were also assessed. Of these, two ultimately required additional treatment, both involving an increase in size of pre-existing aneurysm rather than newly developed aneurysm (Fig. 3 ). Table 3 Cases of De Novo aneurysm formation following ICA trapping Case Sex Age Indication Location EC-IC bypass surgery ACoA PCoA Dominant collateral Aneurysm Venous filling Method f/u period (months) Incidence (months) HTN Smoking FHx Tx Progress 1 26 M Primary aneurysm Cavernous 0 Grad 2 Grad 2 = ACoA tiny aneurysm symmetrical proximal trapping 134.3 134.3 - + 0 No No 2 45 M Primary aneurysm Cavernous 0 Grad 2 Grad 1 ACoA ACoA tiny aneurysm symmetrical both trapping 11.7 11.7 - + 0 No No 3 52 F Primary aneurysm Cavernous 0 Grad 1 Grad 2 PCoA ACoA tiny aneurysm symmetrical both trapping 37.7 6.5 - - 0 No No 4 50 F Primary aneurysm Cavernous 0 Grad 2 Grad 2 PCoA PCA tiny aneurysm symmetrical both trapping 163.9 10.1 - - 0 No No 5 74 F Primary aneurysm Cavernous 0 Grad 2 Grad 0 ACoA Wide neck ACoA aneurysm symmetrical proximal trapping 127.9 127.9 + - 0 No No 6 53 F Primary aneurysm Cavernous 0 Grad 2 Grad 1 ACoA Terminal ICAb aneurysm symmetrical both trapping 129.9 5.9 - - 0 No No 7 69 F Primary aneurysm Cavernous 0 Grad 2 Grad 2 ACoA Known contralateral cavernous aneurysm growth symmetrical proximal trapping 96.3 18 + - 0 Yes Yes 8 51 F Primary aneurysm Cervical 0 Grad 2 Grad 1 ACoA ACoA aneurysm symmetrical both trapping 114.3 107.9 - - 0 No No 9 48 M Primary aneurysm Paraclinoid 1 Grad 1 Grad 0 ACoA Previous ACoA & paraclinoid aneurysm growth symmetrical proximal trapping 63.0 3.2 + + 0 Yes Yes 10 15 F Primary aneurysm Cavernous + PCA 0 Grad 2 Grad 0 ACoA SCA aneurysm symmetrical both trapping 98.5 54.5 - - 0 No No DISCUSSION This retrospective study evaluated the prognosis following endovascular ICA trapping for various indications. The development of new aneurysms after ICA trapping was observed exclusively in the AT group, indicating the importance of the underlying etiology for the trapping procedure. Among patients who developed new aneurysms, more than half were located in the ACoA complex, with most exhibiting well-developed ACoA collateral, suggesting a hemodynamic cause for aneurysm formation. Additionally, the findings confirmed that new aneurysms tended to develop primarily within the first two years. In previous studies on de novo aneurysm formation following ICA occlusion, the reported incidence rate was 4.3%. 9 In contrast, the AT group in the present study showed a significantly higher prevalence rate of 27%. Differences were also observed in the locations of de novo aneurysms. Previous case reports mainly involved the ACoA (27%), PCoA (22%), and ICA (11%), with multiple aneurysms reported in 17% of cases. In the present study, 60% of aneurysms occurred in the ACoA and 20% in the ICA. These differences may be attributed to the categorization of aneurysms by aneurysmal versus non-aneurysmal causes, inclusion of trapping for non-aneurysmal causes, and classification of significant growth of pre-existing aneurysms as new events. Moreover, while previous studies included trapping cases related to MCA and ACoA aneurysms, the present study was limited to cases involving ICA aneurysms. An interesting observation was the relationship between aneurysm location and the state of collateral circulation. Among the 10 patients with de novo aneurysms, many demonstrated favorable ACoA collateral status. This likely accounts for the predominance of aneurysms in the ACoA complex within the registry. Specifically, in patients who developed ACoA aneurysms (Table 3 ), the ACoA was identified as the dominant collateral. These findings suggest that hemodynamic compensation through the ACoA following ICA trapping may contribute to the development of these aneurysms. Additional support for this mechanism is provided by Case 4 in Table 3 , where a patient with dominant PCoA collateral developed an aneurysm at the ipsilateral PCA, specifically at the PCoA branching point, after ICA trapping. The finding that all de novo aneurysms occurred exclusively in the AT group is also noteworthy. Despite undergoing the same ICA trapping procedure, no new aneurysms developed in the NT group. While hemodynamic factors, as previously discussed, may be significant, patient-specific intrinsic factors also appear to play a role in aneurysm formation. 11 In cases where ICA trapping was performed due to non-aneurysmal causes, such as trauma, dissection, pseudo-aneurysm, or other non-aneurysmal causes, no de novo aneurysms were observed. Among the 10 cases of newly developed aneurysms, further evaluation was conducted to determine whether these aneurysms grew or progressed over continuous follow-up and required treatment. Additional treatment was necessary in two cases, both involving pre-existing aneurysms that had increased in size. These findings suggest that, although new aneurysms may develop due to hemodynamic factors and intrinsic conditions following ICA trapping, none of the de novo aneurysms observed in this study required treatment. In contrast, only pre-existing aneurysms necessitated intervention. Therefore, careful monitoring is essential when a pre-existing aneurysm is located in a region subject to hemodynamic compensation after ICA trapping. This study has several limitations. First, a notable sex imbalance was present between the AT and NT groups. Aneurysms are more commonly found in female patients, whereas the NT group included a higher proportion of male patients due to the inclusion of tumor-related causes. This sex difference may have influenced the observed rates of de novo aneurysm formation and should be considered as a potential factor. Second, the NT group had a limited sample size, restricting the ability to assess statistical significance in aneurysm formation. Many patients who underwent ICA trapping in the NT group did not, or could not, undergo angiographic follow up. This was primarily due to the poor prognosis of many patients in the NT group, particularly those with malignancies, who did not undergo follow-up. Additionally, some patients were referred from other clinical departments after ICA trapping and did not return to the radiology department for intracranial angiogram follow up. These factors contributed to the limited number of cases in the NT group. CONCLUSION This study provides valuable insights into the mechanisms of de novo aneurysm formation and aneurysm growth following ICA trapping, highlighting the importance of collateral circulation status and the underlying cause of trapping. When ICA trapping is required, vigilance is essential for detecting de novo aneurysm or pre-existing aneurysm growth in hemodynamically compensated regions, particularly during the first few years and in cases with aneurysmal etiology. Declarations FUNDING This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)(RS-2023-00280269) Ethical approval and informed consent statements. CONFLICTS OF INTEREST The authors declare that they have no competing interests. ETHICAL APPROVAL This retrospective study was approved by the Institutional Review Board of Asan Medical Center, Seoul, Korea (IRB No. 2025-0697). All procedures were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments. INFORMED CONSENT The requirement for informed consent was waived by the Institutional Review Board because of the retrospective design of the study. DATA AVAILABILITY The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. Author Contribution JSY and MHK contributed equally to this work and share first authorship. JSY and MHK conceptualized and designed the study. JTY and JHL collected and organized the clinical and imaging data. BK and YS contributed to data analysis and interpretation. MHK drafted the initial manuscript. DHL supervised the study and critically revised the manuscript. All authors read and approved the final version of the manuscript. References Kaschner MG, Kraus B, Petridis A, Turowski B. Endovascular treatment of intracranial 'blister' and dissecting aneurysms. Neuroradiol J. 2019;32(5):353-65. Dacus MR, Nickele C, Welch BG, Ban VS, Ringer AJ, Kim LJ, et al. Matricidal cavernous aneurysms: a multicenter case series. J Neurointerv Surg. 2019;11(6):584-90. Larson JJ, Tew JM, Jr., Tomsick TA, van Loveren HR. Treatment of aneurysms of the internal carotid artery by intravascular balloon occlusion: long-term follow-up of 58 patients. Neurosurgery. 1995;36(1):26-30; discussion Shakur SF, Alaraj A, Mendoza-Elias N, Osama M, Charbel FT. Hemodynamic characteristics associated with cerebral aneurysm formation in patients with carotid occlusion. J Neurosurg. 2019;130(3):917-22. Tsukada T, Izumi T, Isoda H, Nishihori M, Kropp AE, Mizuno T, et al. Comparison of hemodynamic stress in healthy vessels after parent artery occlusion and flow diverter stent treatment for internal carotid artery aneurysm. J Neurosurg. 2022;136(3):619-26. Jin SC, Choi CG, Kwon DH. Development of 'De novo' Aneurysm after Therapeutic Carotid Occlusion. J Korean Neurosurg Soc. 2009;45(4):236-9. Arnaout OM, Rahme RJ, Aoun SG, Daou MR, Batjer HH, Bendok BR. De novo large fusiform posterior circulation intracranial aneurysm presenting with subarachnoid hemorrhage 7 years after therapeutic internal carotid artery occlusion: case report and review of the literature. Neurosurgery. 2012;71(3):E764-71. Briganti F, Cirillo S, Caranci F, Esposito F, Maiuri F. Development of "de novo" aneurysms following endovascular procedures. Neuroradiology. 2002;44(7):604-9. Arambepola PK, McEvoy SD, Bulsara KR. De novo aneurysm formation after carotid artery occlusion for cerebral aneurysms. Skull Base. 2010;20(6):405-8. Wang YY, Rosenfeld JV, Lyon SM, O'Brien BJ. Rapid development of a de novo intracranial aneurysm following carotid occlusion. J Clin Neurosci. 2008;15(3):324-30. Backes D, Rinkel GJE, Greving JP, Velthuis BK, Murayama Y, Takao H, et al. ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms. Neurology. 2017;88(17):1600-6. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7421358","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":512087253,"identity":"9034c12c-4620-4290-80e8-138b27a93775","order_by":0,"name":"Jun Sang Yoo","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Jun","middleName":"Sang","lastName":"Yoo","suffix":""},{"id":512087254,"identity":"0dd26606-8659-4ec5-af96-120df3ed1039","order_by":1,"name":"Mi Hyeon Kim","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Mi","middleName":"Hyeon","lastName":"Kim","suffix":""},{"id":512087255,"identity":"07098f1b-c18d-49c4-946f-3a289072fd94","order_by":2,"name":"Jong-Tae Yoon","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Jong-Tae","middleName":"","lastName":"Yoon","suffix":""},{"id":512087256,"identity":"7b6749af-bdf3-4788-baec-2cb8db730a30","order_by":3,"name":"Jae Ho Lee","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Jae","middleName":"Ho","lastName":"Lee","suffix":""},{"id":512087257,"identity":"eb2eb7b9-4838-4ce2-8b81-8c224bdac22d","order_by":4,"name":"Boseong Kwon","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Boseong","middleName":"","lastName":"Kwon","suffix":""},{"id":512087258,"identity":"4e82aec7-d2a9-4e38-82f6-d86331d50977","order_by":5,"name":"Yunsun Song","email":"","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Yunsun","middleName":"","lastName":"Song","suffix":""},{"id":512087259,"identity":"f2183ad6-d3b3-4a7f-87ed-cec3ad61d4f7","order_by":6,"name":"Deok Hee Lee","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzUlEQVRIiWNgGAWjYDCCG8wNDAwVcK4FgwRhLYxALWfgXAkitTC2kaKF73Zj44OP8+yi+RvYHz742CbBIDn7AH4tkncONhvO3JacO+MAj7HhTKAWab4E/FoMbiS2SfNuY87dwMDDJs0L1CLHQ8BhQC3tv//OqQdqYX/+m1gtbcyMDYeBWhjMmEFapAlpkbyR2CzZc+x47ozDPMaSM85J8Ej2ENDCdyP54IcfNdW5/e3tDz98KLORkzhDQAsCMEMoQs4aBaNgFIyCUUAMAAC2PT/fh5cGbgAAAABJRU5ErkJggg==","orcid":"","institution":"Asan Medical Center, University of Ulsan College of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Deok","middleName":"Hee","lastName":"Lee","suffix":""}],"badges":[],"createdAt":"2025-08-21 02:08:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7421358/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7421358/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00062-025-01585-6","type":"published","date":"2025-11-06T15:58:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90939241,"identity":"a76ee3a9-3cf6-4a48-9ac4-87113f171316","added_by":"auto","created_at":"2025-09-09 17:47:55","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":68324,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of patient inclusion and analysis. A total of 84 patients initially underwent unilateral internal carotid artery (ICA) trapping. After excluding 37 patients due to insufficient follow-up imaging (\u0026lt; 1 year), 47 patients were included in the final analysis and categorized into aneurysm-trapping (n = 37) and non-aneurysm-trapping (n = 10) groups based on the primary indication for ICA sacrifice. The analysis focused on evaluating the incidence of de novo aneurysm formation and the growth of pre-existing lesions.\u003c/p\u003e","description":"","filename":"ASMEC6010Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7421358/v1/6bc8cd59a26029af7b1d418e.jpg"},{"id":90940533,"identity":"a599b0a8-85b2-4670-a268-575b02a4d20e","added_by":"auto","created_at":"2025-09-09 18:03:55","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":26381,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative case of a female patient in her early 50s with a giant aneurysm of the right cervical internal carotid artery (ICA), treated with endovascular ICA trapping. Pre-procedural digital subtraction angiography (DSA) demonstrates a large cervical ICA aneurysm \u003cstrong\u003e(A)\u003c/strong\u003e. Immediate post-procedural DSA confirms successful ICA trapping with prompt cross-filling of the right ICA territory via a patent ACoA \u003cstrong\u003e(B)\u003c/strong\u003e. Magnetic resonance angiography (MRA) performed one day post-trapping shows adequate collateral circulation through the Circle of Willis without evidence of aneurysm \u003cstrong\u003e(C)\u003c/strong\u003e. A three-dimensional volume-rendered reconstruction of CTA obtained 9 years later demonstrates a small, superiorly projecting aneurysm arising from the left side of the ACoA \u003cstrong\u003e(D)\u003c/strong\u003e.\u003c/p\u003e","description":"","filename":"ASMEC6010Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7421358/v1/800a10dcba28e84173b343ec.jpg"},{"id":90939242,"identity":"4004666d-966f-42c7-b662-df269a6c0919","added_by":"auto","created_at":"2025-09-09 17:47:55","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":23320,"visible":true,"origin":"","legend":"\u003cp\u003eSequential imaging of a female patient in her early 70s demonstrates progressive transformation of a pre-existing subtle vascular abnormality into a giant aneurysm following contralateral ICA trapping. At diagnosis, a giant aneurysm of the left cavernous ICA was identified \u003cstrong\u003e(A)\u003c/strong\u003e. Simultaneous CTA revealed mild dilatation of the right cavernous ICA, not meeting pathological criteria \u003cstrong\u003e(B)\u003c/strong\u003e. However, follow-up angiography 2.5 years after ICA trapping showed that the right cavernous ICA had evolved into a prominent fusiform aneurysm \u003cstrong\u003e(C)\u003c/strong\u003e. The lesion continued to enlarge over time, reaching a maximum diameter of 23 mm after an additional 6.4 years \u003cstrong\u003e(D)\u003c/strong\u003e.\u003c/p\u003e","description":"","filename":"ASMEC6010Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7421358/v1/960b5c449ca8adb960c70052.jpg"},{"id":95564204,"identity":"92d2dc30-2d1a-4ac0-9134-b366507b61b0","added_by":"auto","created_at":"2025-11-10 16:08:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":829656,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7421358/v1/8276c90c-7d6c-4797-ba2b-4d4a65c7fd83.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"De Novo Aneurysm Formation After Internal Carotid Artery Sacrifice: Impact of Aneurysmal Versus Non-Aneurysmal Etiology","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eEndovascular internal carotid artery (ICA) trapping has historically been a widely used technique, particularly in cases where conventional reconstructive options such as clipping, coiling, or stent placement are not feasible. In recent years, the advent of flow diversion therapy has transformed the treatment paradigm for many complex aneurysms, enabling vessel-preserving strategies even in anatomically challenging lesions.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e However, despite these advances, certain clinical scenarios still require ICA trapping as a definitive treatment for aneurysmal disease,\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e particularly when flow diversion is contraindicated, has failed, or is technically unfeasible due to anatomical or hemodynamic factors. Furthermore, ICA sacrifice remains indispensable in the management of various non-aneurysmal pathologies, such as traumatic pseudoaneurysms, arterial ruptures, dissections, or carotid-cavernous fistulas, where vessel preservation is either not a priority or not possible. In such cases, endovascular ICA trapping, either alone or in conjunction with extracranial-intracranial (EC-IC) bypass surgery, continues to serve as a valuable and effective therapeutic option, particularly when adequate collateral flow is confirmed.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eHowever, one of the known drawbacks of this approach is the hemodynamic alteration that follows ICA sacrifice. Flow redistribution within the circle of Willis (COW) inevitably leads to increased hemodynamic stress along collateral channels, particularly the anterior communicating artery (ACoA) and posterior communicating artery (PCoA), which are called upon to compensate for the loss of antegrade ICA flow.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e This shift in hemodynamic burden has been associated with de novo aneurysm formation, often at sites that were previously unaffected. While this phenomenon is well acknowledged, current evidence is largely limited to small case series and anecdotal reports, highlighting the need for more comprehensive long-term data.\u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8 CR9\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eAt our institution, endovascular ICA trapping has been performed over an extended period, with many patients undergoing long-term imaging surveillance. Based on this clinical experience, a single-center retrospective analysis was conducted with the following objectives: (1) to determine the incidence, location, size, and rupture status of de novo aneurysms occurring after ICA trapping, and (2) to investigate whether the underlying indication for ICA trapping, aneurysmal versus non-aneurysmal, affects the risk or pattern of de novo aneurysm development.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003ePatients\u003c/h2\u003e\u003cp\u003ePatients who underwent unilateral endovascular ICA trapping at our institution were retrospectively identified from the neurointerventional procedure database, regardless of the underlying indication. The study was conducted between 2003, when the picture archiving and communication system began storing angiographic imaging data, and 2023. Patients were included if they had available imaging follow-up of at least one year after ICA trapping using any vascular imaging modality, including computed tomography (CT) angiography, magnetic resonance (MR) angiography (with or without contrast enhancement), or cerebral digital subtraction angiography (DSA). Patients without adequate imaging follow-up during this period were excluded (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eDemographic and clinical data, including aneurysm risk factors such as hypertension, smoking, and family history of aneurysm, were retrospectively collected from a registry using electronic medical record data. The primary indication for ICA trapping was reviewed for each patient, and individuals were categorized into two groups based on the underlying etiology. Patients who underwent ICA trapping primarily for the treatment of aneurysmal lesions were classified as the \u0026lsquo;aneurysm-trapping (AT) group.\u0026rsquo; In contrast, those who underwent ICA trapping for non-aneurysmal causes were assigned to the \u0026lsquo;non-aneurysm-trapping (NT) group.\u0026rsquo; The NT group included cases of traumatic ICA injury (e.g., dissection, pseudoaneurysm, or rupture), iatrogenic ICA injury (e.g., cavernous ICA perforation during transsphenoidal surgery), carotid blowout syndrome associated with head and neck malignancy, and carotid-cavernous fistulas, representing a spectrum of non-aneurysmal conditions.\u003c/p\u003e\u003cp\u003eThis study was conducted with approval from the Institutional Review Board (IRB) of our institution, and the requirement for informed consent was waived owing to the retrospective nature of the study (IRB number: 2025\u0026thinsp;\u0026minus;\u0026thinsp;0697).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eNeurovascular imaging\u003c/h3\u003e\n\u003cp\u003eThis retrospective imaging analysis utilized data collected over a 20-year period from 2003 to 2025. Due to the diversity of MR angiography, CT angiography, and DSA equipment models and image acquisition parameters used during this period, a comprehensive listing of all imaging equipment was impractical. Therefore, representative imaging equipment and parameters commonly used during this period are summarized below. MR imaging was performed using 3.0T MRI systems, including Ingenia and Achieva (Philips Healthcare, Best, Netherlands), with repetition time (TR)/echo time (TE)\u0026thinsp;=\u0026thinsp;25/3.5 ms, flip angle (FA)\u0026thinsp;=\u0026thinsp;20\u0026deg;, field of view (FOV)\u0026thinsp;=\u0026thinsp;200 \u0026times; 250 \u0026times; 100 mm, matrix\u0026thinsp;=\u0026thinsp;880 \u0026times; 880, and slice thickness\u0026thinsp;=\u0026thinsp;1 mm; and MAGNETOM Vida (Siemens Healthineers, Erlangen, Germany) with TR/TE\u0026thinsp;=\u0026thinsp;21.3/3.7 ms, FA\u0026thinsp;=\u0026thinsp;20\u0026deg;, FOV\u0026thinsp;=\u0026thinsp;200 \u0026times; 220 mm, matrix\u0026thinsp;=\u0026thinsp;648 \u0026times; 594, and slice thickness\u0026thinsp;=\u0026thinsp;0.40 mm. CT angiography was performed using a 16-slice CT scanner (Lightspeed Ultra, GE Healthcare, Waukesha, WI, USA) with tube voltage\u0026thinsp;=\u0026thinsp;120 kV, tube current\u0026thinsp;=\u0026thinsp;400 mA, exposure time\u0026thinsp;=\u0026thinsp;0.50 s, mAs\u0026thinsp;=\u0026thinsp;200, display FOV (DFOV)\u0026thinsp;=\u0026thinsp;210 mm, and slice thickness\u0026thinsp;=\u0026thinsp;0.63 mm. Additionally, 128-slice CT scanners (SOMATOM Definition Flash, Siemens Healthineers, Forchheim, Germany, and SOMATOM Definition Edge, Siemens Healthineers, Erlangen, Germany) were used with tube voltage\u0026thinsp;=\u0026thinsp;120 kV, tube current\u0026thinsp;=\u0026thinsp;300\u0026ndash;400 mA, exposure time\u0026thinsp;=\u0026thinsp;0.50 s, mAs\u0026thinsp;=\u0026thinsp;200, DFOV\u0026thinsp;=\u0026thinsp;200 mm, and slice thickness\u0026thinsp;=\u0026thinsp;1 mm. Conventional angiography and embolization were performed using a biplane angiography machine (Artis zee; Siemens Healthineers, Forchheim, Germany).\u003c/p\u003e\n\u003ch3\u003ePre- or intra-procedural angiography analysis\u003c/h3\u003e\n\u003cp\u003eIn the AT group, pre-trapping angiography was used to document the maximum size and location of the index aneurysm, as well as the presence, size, and location of any additional aneurysms in other arterial segments. Collateral status during test balloon occlusion was assessed by evaluating the presence and caliber of ACoA and PCoA. The caliber of these communicating arteries was categorized into three grades reflecting collateral flow capacity: grade 0 for absent or rudimentary channels, grade 1 for partially developed but insufficient channels, and grade 2 for well-developed and hemodynamically competent channels. In selected cases, EC-IC bypass surgery was performed when collateral circulation was deemed insufficient based on test balloon occlusion results. Brain perfusion single photon emission CT imaging was additionally used to support the decision for bypass surgery in elective cases; however, it was omitted in emergent settings where trapping was urgently required.\u003c/p\u003e\n\u003ch3\u003eFollow-up angiography analysis\u003c/h3\u003e\n\u003cp\u003eVascular imaging was routinely performed on post-procedure day 1 following ICA trapping. For subsequent follow-up, intracranial angiographic studies, primarily time-of-flight MR angiography (TOF-MRA), and occasionally contrast-enhanced MR angiography or CT angiography (CTA), were conducted, depending on the embolization method and clinical context. TOF-MRA was preferred in most cases, particularly those treated with platinum embolization coils, whereas CTA was more commonly used in cases involving detachable balloons.\u003c/p\u003e\u003cp\u003eFollow-up imaging focused on assessing the completeness of trapping and evaluating the COW, with particular attention to changes in collateral flow and the development of new vascular lesions. Specifically, the presence of de novo aneurysms, defined as any newly identified arterial bulging lesion not visible on pre-trapping baseline imaging, was assessed. Interval growth of pre-existing aneurysms, if any, was also documented. In patients with pre-existing aneurysms, interval growth was determined based on expert consensus. De novo aneurysm formation and interval growth of pre-existing aneurysm were considered present when two board-certified neurointerventional radiologists independently agreed that a visible increase in aneurysm size had occurred on follow-up imaging, compared with baseline. In cases of disagreement, a senior adjudicator reviewed the images and made the final determination. Lesions with poorly defined margins or insufficient image quality were excluded from the analysis to minimize interpretation bias. For all aneurysmal events, the location and time of detection during follow-up were recorded.\u003c/p\u003e\u003cp\u003eCollateral circulation status was analyzed based on balloon occlusion testing prior to trapping, with grading of the ACoA and PCoA according to their size and flow adequacy. This was also recorded when EC-IC bypass was performed.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eA comprehensive statistical comparison was performed to evaluate patient demographics, clinical data including risk factors, and angiographic characteristics. Comparisons were performed between the AT (n\u0026thinsp;=\u0026thinsp;37) and NT (n\u0026thinsp;=\u0026thinsp;10) groups based on the underlying etiology requiring ICA trapping, followed by subgroup comparison within the AT group between those with and without de novo aneurysm (n\u0026thinsp;=\u0026thinsp;37). Student\u0026rsquo;s t-tests were used for continuous variables, and chi-square tests were applied to categorical variables. Continuous data are presented as means with standard deviations, and categorical data are expressed as frequencies and percentages. All statistical analyses were performed using SPSS version 19.0 (IBM Corp., Armonk, NY, USA), and a p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eAs illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, a total of 84 patients underwent endovascular ICA trapping at our institution between January 2003 and June 2023. Of these, 37 patients were excluded due to the absence of angiographic follow-up for at least one year, leaving 47 patients eligible for analysis. Among the included cohort, 37 patients (78.7%) were classified into the AT group and 10 patients (21.3%) into the NT group, based on the underlying etiology necessitating ICA trapping.\u003c/p\u003e\n\u003ch3\u003eComparison between AT group and NT group\u003c/h3\u003e\n\u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the AT and NT groups had a well-balanced age distribution but showed a significant difference in sex, with a higher proportion of female patients in the AT group (78.4% vs. 20.0%, p\u0026thinsp;=\u0026thinsp;0.001). No statistically significant difference in aneurysm risk factors were observed between the two groups. Additionally, the frequency of EC-IC bypass surgery and aneurysm laterality did not differ notably. The interval from ICA trapping to the final angiographic imaging follow-up was longer in the AT group than in the NT group (67.9\u0026thinsp;\u0026plusmn;\u0026thinsp;43.1 months vs. 35.2\u0026thinsp;\u0026plusmn;\u0026thinsp;30.3 months, p\u0026thinsp;=\u0026thinsp;0.013). Comparison of COW collaterals showed similar grading of the ACoA and PCoA between the two groups.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePatient characteristics between the aneurysm-trapping and non-aneurysm-trapping groups following ICA trapping\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAneurysm-trapping group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;37)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-aneurysm-trapping group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;10)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDemographic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex, male (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (21.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8 (80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e53.4\u0026thinsp;\u0026plusmn;\u0026thinsp;14.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e51.4\u0026thinsp;\u0026plusmn;\u0026thinsp;19.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.918\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAneurysm risk factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13 (35.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.776\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of smoking (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6 (16.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3 (30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.326\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFamily history of aneurysm (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (2.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.721\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAneurysm formation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10 (27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.064\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLocation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSize\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSide (right) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23 (62.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.487\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003es/p Bypass OP (EC-IC) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (21.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3 (30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.579\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatency of ACoA (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20 (54.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.820\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatency of PCoA (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20 (54.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.430\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, median (IQR), or number (%).\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eEC-IC, extracranial-intracrania; OP, operation; ACoA, anterior communicating artery; PCoA, posterior communicating artery.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison between groups with and without de novo aneurysm formation\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDe novo aneurysm (+)\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;10)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDe novo aneurysm (-)\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDemographic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex, male (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e5 (18.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.451\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e48.3\u0026thinsp;\u0026plusmn;\u0026thinsp;17.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e55.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.292\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAneurysm risk factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e10 (37.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.690\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of smoking (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3 (11.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.166\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFamily history of aneurysm (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0 (0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1 (3.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.537\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInterval period (months)\u003c/p\u003e\u003cp\u003e(until incidence or last F/U)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e121.7\u0026thinsp;\u0026plusmn;\u0026thinsp;137.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e144.2\u0026thinsp;\u0026plusmn;\u0026thinsp;92.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.642\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVascular features\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSide (right) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5 (50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e18 (66.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.353\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003es/p Bypass OP (EC-IC) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7 (25.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.296\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatency of ACoA (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12 (44.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.054\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatency of PCoA (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e16 (59.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.297\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, median (IQR), or number (%).\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eEC-IC, extracranial-intracranial; OP, operation; ACoA, anterior communicating artery; PCoA, posterior communicating artery.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eDe-novo aneurysm formation (n\u0026thinsp;=\u0026thinsp;9, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) or significant pre-existing aneurysm growth (n\u0026thinsp;=\u0026thinsp;1, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) was observed in 10 patients, all within the AT group. However, the difference did not reach statistical significance due to small number of patients in the NT group (10/27 vs. 0/10, p\u0026thinsp;=\u0026thinsp;0.064).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eWhen comparing patients who developed new aneurysms or exhibited pre-existing aneurysm growth (n\u0026thinsp;=\u0026thinsp;10) with those who did not (n\u0026thinsp;=\u0026thinsp;27) within the AT group (n\u0026thinsp;=\u0026thinsp;37), no significant differences were observed in age, sex, aneurysm laterality, aneurysm risk factors, or follow up interval days. Regarding COW collateral status, a higher proportion of patients with well-developed ACoA collateral was identified in the de novo aneurysm group, although the difference did not reach statistical significance (80% vs. 44.4%, p\u0026thinsp;=\u0026thinsp;0.054)\u003c/p\u003e\u003cp\u003eAll 10 patients who developed a new aneurysm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) or exhibited enlargement of a pre-existing aneurysm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) during the follow-up period were individually reviewed, and details are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Among the 10 new aneurysms identified, six were located in the ACoA complex, two in the ICA (one de novo aneurysm and one interval growth of preexisting aneurysm), one in the PCA, and one in the SCA. Regarding the interval to aneurysm formation, six patients were identified within 19.7 months, whereas three were detected late due to delayed angiographic follow up. The progression and treatment requirements of all 10 aneurysms were also assessed. Of these, two ultimately required additional treatment, both involving an increase in size of pre-existing aneurysm rather than newly developed aneurysm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCases of De Novo aneurysm formation following ICA trapping\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"19\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c17\" colnum=\"17\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c18\" colnum=\"18\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c19\" colnum=\"19\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIndication\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLocation\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eEC-IC bypass surgery\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePCoA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eDominant collateral\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eAneurysm\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eVenous filling\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eMethod\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003ef/u period\u003c/p\u003e\u003cp\u003e(months)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eIncidence (months)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eHTN\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c16\"\u003e\u003cp\u003eSmoking\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c17\"\u003e\u003cp\u003eFHx\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c18\"\u003e\u003cp\u003eTx\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c19\"\u003e\u003cp\u003eProgress\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e=\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eACoA tiny aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eproximal trapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e134.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e134.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eACoA tiny aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e11.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e11.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003ePCoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eACoA tiny aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e37.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003ePCoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003ePCA tiny aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e163.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e10.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eWide neck ACoA aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eproximal\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e127.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e127.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eTerminal ICAb aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e129.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eKnown contralateral cavernous aneurysm growth\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eproximal\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e96.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCervical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eACoA aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e114.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e107.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eParaclinoid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003ePrevious ACoA \u0026amp; paraclinoid aneurysm growth\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eproximal\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e63.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrimary\u003c/p\u003e\u003cp\u003eaneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCavernous\u003c/p\u003e\u003cp\u003e+\u003c/p\u003e\u003cp\u003ePCA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGrad 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGrad 0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eACoA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eSCA aneurysm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003esymmetrical\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eboth\u003c/p\u003e\u003cp\u003etrapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e98.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e54.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c17\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c18\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c19\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis retrospective study evaluated the prognosis following endovascular ICA trapping for various indications. The development of new aneurysms after ICA trapping was observed exclusively in the AT group, indicating the importance of the underlying etiology for the trapping procedure. Among patients who developed new aneurysms, more than half were located in the ACoA complex, with most exhibiting well-developed ACoA collateral, suggesting a hemodynamic cause for aneurysm formation. Additionally, the findings confirmed that new aneurysms tended to develop primarily within the first two years.\u003c/p\u003e\u003cp\u003eIn previous studies on de novo aneurysm formation following ICA occlusion, the reported incidence rate was 4.3%.\u003csup\u003e9\u003c/sup\u003e In contrast, the AT group in the present study showed a significantly higher prevalence rate of 27%. Differences were also observed in the locations of de novo aneurysms. Previous case reports mainly involved the ACoA (27%), PCoA (22%), and ICA (11%), with multiple aneurysms reported in 17% of cases. In the present study, 60% of aneurysms occurred in the ACoA and 20% in the ICA. These differences may be attributed to the categorization of aneurysms by aneurysmal versus non-aneurysmal causes, inclusion of trapping for non-aneurysmal causes, and classification of significant growth of pre-existing aneurysms as new events. Moreover, while previous studies included trapping cases related to MCA and ACoA aneurysms, the present study was limited to cases involving ICA aneurysms.\u003c/p\u003e\u003cp\u003eAn interesting observation was the relationship between aneurysm location and the state of collateral circulation. Among the 10 patients with de novo aneurysms, many demonstrated favorable ACoA collateral status. This likely accounts for the predominance of aneurysms in the ACoA complex within the registry. Specifically, in patients who developed ACoA aneurysms (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), the ACoA was identified as the dominant collateral. These findings suggest that hemodynamic compensation through the ACoA following ICA trapping may contribute to the development of these aneurysms. Additional support for this mechanism is provided by Case 4 in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, where a patient with dominant PCoA collateral developed an aneurysm at the ipsilateral PCA, specifically at the PCoA branching point, after ICA trapping.\u003c/p\u003e\u003cp\u003eThe finding that all de novo aneurysms occurred exclusively in the AT group is also noteworthy. Despite undergoing the same ICA trapping procedure, no new aneurysms developed in the NT group. While hemodynamic factors, as previously discussed, may be significant, patient-specific intrinsic factors also appear to play a role in aneurysm formation.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e In cases where ICA trapping was performed due to non-aneurysmal causes, such as trauma, dissection, pseudo-aneurysm, or other non-aneurysmal causes, no de novo aneurysms were observed.\u003c/p\u003e\u003cp\u003eAmong the 10 cases of newly developed aneurysms, further evaluation was conducted to determine whether these aneurysms grew or progressed over continuous follow-up and required treatment. Additional treatment was necessary in two cases, both involving pre-existing aneurysms that had increased in size. These findings suggest that, although new aneurysms may develop due to hemodynamic factors and intrinsic conditions following ICA trapping, none of the de novo aneurysms observed in this study required treatment. In contrast, only pre-existing aneurysms necessitated intervention. Therefore, careful monitoring is essential when a pre-existing aneurysm is located in a region subject to hemodynamic compensation after ICA trapping.\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, a notable sex imbalance was present between the AT and NT groups. Aneurysms are more commonly found in female patients, whereas the NT group included a higher proportion of male patients due to the inclusion of tumor-related causes. This sex difference may have influenced the observed rates of de novo aneurysm formation and should be considered as a potential factor. Second, the NT group had a limited sample size, restricting the ability to assess statistical significance in aneurysm formation. Many patients who underwent ICA trapping in the NT group did not, or could not, undergo angiographic follow up. This was primarily due to the poor prognosis of many patients in the NT group, particularly those with malignancies, who did not undergo follow-up. Additionally, some patients were referred from other clinical departments after ICA trapping and did not return to the radiology department for intracranial angiogram follow up. These factors contributed to the limited number of cases in the NT group.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThis study provides valuable insights into the mechanisms of de novo aneurysm formation and aneurysm growth following ICA trapping, highlighting the importance of collateral circulation status and the underlying cause of trapping. When ICA trapping is required, vigilance is essential for detecting de novo aneurysm or pre-existing aneurysm growth in hemodynamically compensated regions, particularly during the first few years and in cases with aneurysmal etiology.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFUNDING\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)(RS-2023-00280269)\u003c/p\u003e\n\u003cp\u003eEthical approval and informed consent statements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONFLICTS OF INTEREST\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eETHICAL APPROVAL\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective study was approved by the Institutional Review Board of Asan Medical Center, Seoul, Korea (IRB No. 2025-0697). All procedures were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eINFORMED CONSENT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe requirement for informed consent was waived by the Institutional Review Board because of the retrospective design of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDATA AVAILABILITY\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJSY and MHK contributed equally to this work and share first authorship. JSY and MHK conceptualized and designed the study. JTY and JHL collected and organized the clinical and imaging data. BK and YS contributed to data analysis and interpretation. MHK drafted the initial manuscript. DHL supervised the study and critically revised the manuscript. All authors read and approved the final version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKaschner MG, Kraus B, Petridis A, Turowski B. Endovascular treatment of intracranial \u0026apos;blister\u0026apos; and dissecting aneurysms. Neuroradiol J. 2019;32(5):353-65.\u003c/li\u003e\n\u003cli\u003eDacus MR, Nickele C, Welch BG, Ban VS, Ringer AJ, Kim LJ, et al. Matricidal cavernous aneurysms: a multicenter case series. J Neurointerv Surg. 2019;11(6):584-90.\u003c/li\u003e\n\u003cli\u003eLarson JJ, Tew JM, Jr., Tomsick TA, van Loveren HR. Treatment of aneurysms of the internal carotid artery by intravascular balloon occlusion: long-term follow-up of 58 patients. Neurosurgery. 1995;36(1):26-30; discussion \u003c/li\u003e\n\u003cli\u003eShakur SF, Alaraj A, Mendoza-Elias N, Osama M, Charbel FT. Hemodynamic characteristics associated with cerebral aneurysm formation in patients with carotid occlusion. J Neurosurg. 2019;130(3):917-22.\u003c/li\u003e\n\u003cli\u003eTsukada T, Izumi T, Isoda H, Nishihori M, Kropp AE, Mizuno T, et al. Comparison of hemodynamic stress in healthy vessels after parent artery occlusion and flow diverter stent treatment for internal carotid artery aneurysm. J Neurosurg. 2022;136(3):619-26.\u003c/li\u003e\n\u003cli\u003eJin SC, Choi CG, Kwon DH. Development of \u0026apos;De novo\u0026apos; Aneurysm after Therapeutic Carotid Occlusion. J Korean Neurosurg Soc. 2009;45(4):236-9.\u003c/li\u003e\n\u003cli\u003eArnaout OM, Rahme RJ, Aoun SG, Daou MR, Batjer HH, Bendok BR. De novo large fusiform posterior circulation intracranial aneurysm presenting with subarachnoid hemorrhage 7 years after therapeutic internal carotid artery occlusion: case report and review of the literature. Neurosurgery. 2012;71(3):E764-71.\u003c/li\u003e\n\u003cli\u003eBriganti F, Cirillo S, Caranci F, Esposito F, Maiuri F. Development of \u0026quot;de novo\u0026quot; aneurysms following endovascular procedures. Neuroradiology. 2002;44(7):604-9.\u003c/li\u003e\n\u003cli\u003eArambepola PK, McEvoy SD, Bulsara KR. De novo aneurysm formation after carotid artery occlusion for cerebral aneurysms. Skull Base. 2010;20(6):405-8.\u003c/li\u003e\n\u003cli\u003eWang YY, Rosenfeld JV, Lyon SM, O\u0026apos;Brien BJ. Rapid development of a de novo intracranial aneurysm following carotid occlusion. J Clin Neurosci. 2008;15(3):324-30.\u003c/li\u003e\n\u003cli\u003eBackes D, Rinkel GJE, Greving JP, Velthuis BK, Murayama Y, Takao H, et al. ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms. Neurology. 2017;88(17):1600-6.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Endovascular trapping, ICA sacrifice, De novo aneurysm, Neurointervention, Coil embolization","lastPublishedDoi":"10.21203/rs.3.rs-7421358/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7421358/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eEndovascular trapping of the internal carotid artery (ICA) remains a definitive treatment for both aneurysmal and non-aneurysmal conditions when vessel-preserving strategies are not feasible. However, increasing attention has been directed toward the risk of de novo aneurysm formation following ICA sacrifice, presumably due to hemodynamic alterations within the Circle of Willis. This study aimed to evaluate the incidence and potential risk factors for de novo aneurysm development after ICA trapping, particularly focusing on differences based on the underlying pathology, aneurysmal versus non-aneurysmal.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eA retrospective, single-center study was conducted on patients who underwent unilateral endovascular ICA trapping between 2003 and 2023, with a minimum of one year of angiographic follow-up. Patients were categorized into the aneurysm-trapping (AT) or non-aneurysm-trapping (NT) group according to the underlying indication for ICA sacrifice. Clinical, angiographic, and procedural data were reviewed to evaluate the development of de novo aneurysms or the progression of pre-existing lesions.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eAmong the 47 included patients (37 and 10 in the AT and NT groups, respectively), de novo aneurysm formation or significant growth of pre-existing aneurysms was observed exclusively in the AT group (10/37, 27.0%), with no such events in the NT group (0/10), although the difference did not reach statistical significance (p\u0026thinsp;=\u0026thinsp;0.064). Most newly developed aneurysms (60%) arose at the anterior communicating artery (ACoA), predominantly in patients with well-developed ACoA collateral flow. Most lesions appeared within two years after ICA trapping. Additional treatment was required in two patients due to progressive enlargement of pre-existing aneurysms.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eDe novo aneurysm formation following ICA trapping appears to occur exclusively in patients with an underlying aneurysmal etiology, particularly at sites of hemodynamic stress such as the ACoA. Close imaging surveillance is recommended during the first two years post-trapping, especially in patients with robust collateral circulation or pre-existing aneurysms.\u003c/p\u003e","manuscriptTitle":"De Novo Aneurysm Formation After Internal Carotid Artery Sacrifice: Impact of Aneurysmal Versus Non-Aneurysmal Etiology","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 17:47:50","doi":"10.21203/rs.3.rs-7421358/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9e904bfc-822a-4c77-9c20-1d70c61131be","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-10T16:05:42+00:00","versionOfRecord":{"articleIdentity":"rs-7421358","link":"https://doi.org/10.1007/s00062-025-01585-6","journal":{"identity":"clinical-neuroradiology","isVorOnly":false,"title":"Clinical Neuroradiology"},"publishedOn":"2025-11-06 15:58:14","publishedOnDateReadable":"November 6th, 2025"},"versionCreatedAt":"2025-09-09 17:47:50","video":"","vorDoi":"10.1007/s00062-025-01585-6","vorDoiUrl":"https://doi.org/10.1007/s00062-025-01585-6","workflowStages":[]},"version":"v1","identity":"rs-7421358","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7421358","identity":"rs-7421358","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}