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Purpose: The routine use of intraoperative digital subtraction angiography (iDSA) increases detection of intracranial aneurysm (IA) remnants after microsurgical clipping. Spontaneous thrombosis of IA remnants after clipping is considered a rare phenomenon. We analyse iDSA characteristics to find predictors for IA remnant thrombosis. Methods: IA with intraoperative detection of a remnant after clipping were identified and divided into remnants experiencing spontaneous thrombosis, and remnants with long-term patency and/or remnant growth. Angiographic features of iDSA were analysed and compared between the two groups. Results: Of 37 IAs with intraoperative remnant on 3D-iDSA, five sustained a spontaneous remnant thrombosis and remained occluded in long-term follow-up. In all five cases, iDSA revealed delayed inflow and consequent stasis of the contrast agent until the late venous phase. On the other hand, in all cases with persistent long-term IA remnants (n = 32) iDSA demonstrated timely arterial contrast inflow and wash-out without stasis of intra-aneurysmal contrast agent. Conclusions: Contrast stasis in IA remnants during iDSA appears to predict long-term IA occlusion, indicating that clip correction manoeuvres or even attempted endovascular treatment of the remnant IA may be avoided in these patients. [ABSTRACT FROM AUTHOR]

Background: Healing of intracranial aneurysms following endovascular treatment relies on the organization of early thrombus into mature scar tissue and neointima formation. Activation and deactivation of the inflammation cascade plays an important role in this process. In addition to timely evolution, its topographic distribution is hypothesized to be crucial for successful aneurysm healing. Methods: Decellularized saccular sidewall aneurysms were created in Lewis rats and coiled. At follow-up (after 3 days (n = 16); 7 days (n = 19); 21 days (n = 8)), aneurysms were harvested and assessed for healing status. In situ hybridization was performed for soluble inflammatory markers (IL6, MMP2, MMP9, TNF-α, FGF23, VEGF), and immunohistochemical analysis to visualize inflammatory cells (CD45, CD3, CD20, CD31, CD163, HLA-DR). These markers were specifically documented for five regions of interest: aneurysm neck, dome, neointima, thrombus, and adjacent vessel wall. Results: Coiled aneurysms showed enhanced patterns of thrombus organization and neointima formation, whereas those without treatment demonstrated heterogeneous patterns of thrombosis, thrombus recanalization, and aneurysm growth (p = 0.02). In coiled aneurysms, inflammation markers tended to accumulate inside the thrombus and in the neointima (p < 0.001). Endothelial cells accumulated directly in the neointima (p < 0.0001), and their presence was associated with complete aneurysm healing. Conclusion: The presence of proinflammatory cells plays a crucial role in aneurysm remodeling after coiling. Whereas thrombus organization is hallmarked by a pronounced intra-thrombotic inflammatory reaction, neointima maturation is characterized by direct invasion of endothelial cells. Knowledge concerning topographic distribution of regenerative inflammatory processes may pave the way for future treatment modalities which enhance aneurysm healing after endovascular therapy. [ABSTRACT FROM AUTHOR]

Background: Growing evidence suggests that three-dimensional digital subtraction angiography (3D-DSA) is superior to 2D-DSA in detection of intracranial aneurysm (IA) remnants after clipping. With a simple, practical quantitative scale proposed to measure maximal remnant dimension on 3D-DSA, this study provides a rigorous interrater and intrarater reliability and agreement study comparing this newly established scale with a commonly used (Sindou) 2D-DSA scale. Method: Records of 43 patients with clipped IAs harboring various sized remnants who underwent 2D- and 3D-DSA between 2012 and 2018 were evaluated. Using the 2D and 3D scales, six raters scored these remnants and repeated the scoring task 8 weeks later. Interrater and intrarater agreement for both grading schemes were calculated using kappa (κ) statistics. Results: Interrater agreement was highly significant, yielding κ-values at 95% CI (p = 0.000) of 0.225 for the first [0.185; 0.265] and 0.368 s [0.328; 0.408] time points for 2D-DSA and values of 0.700 for the first [0.654; 0.745] and 0.776 s [0.729; 0.822] time points for 3D-DSA. Intrarater agreement demonstrated κ-values between 0.139 and 0.512 for 2D-DSA and between 0.487 and 0.813 for 3D-DSA scores. Conclusion: Interrater and intrarater agreement was minimal or weak for 2D-DSA scores, but strong for 3D-DSA scores. We propose that baseline 3D-DSA characterization may prove more reliable when categorizing clipped IA remnants for purposes of risk stratification and lifelong follow-up. [ABSTRACT FROM AUTHOR]

Background and purpose Despite significant technical advances, recanalization rates after endovascular therapy of ruptured intracranial aneurysms (IAs) remain a clinical challenge. A histopathological hallmark of ruptured human IA walls is mural cell loss. Mural smooth muscle cells (SMCs) are known to promote intraluminal healing in thrombosed experimental aneurysms. In this rat model we assess the natural history and healing process after coil embolization in SMC-rich and decellularized aneurysms. Methods Saccular aneurysms were created by end-to-side anastomosis of an arterial graft from the descending thoracic aorta of a syngeneic donor rat to the infrarenal abdominal aorta of recipient male Wistar rats. Untreated arterial grafts were immediately transplanted, whereas aneurysms with loss of mural cells were chemically decellularized before implantation. Aneurysms underwent coil implantation during aneurysm anastomosis. Animals were randomly assigned either to the non-decellularized or decellularized group and underwent macroscopic and histological analyses on days 3, 7, 21, or 90 post-coil implantation. Results A total of 55 rats underwent macroscopic and histologic analysis. After coil embolization, aneurysms with SMC-rich walls showed a linear course of thrombosis and neointima formation whereas decellularized aneurysms showed marked inflammatory wall degeneration with increased recanalization rates 21 days (p=0.002) and 90 days (p=0.037) later. The SMCs showed the ability to actively migrate into the intra-aneurysmal thrombus and participate in thrombus organization. Conclusions Coil embolization of aneurysms with highly degenerated walls is prone to further wall degeneration, increased inflammation, and recanalization compared with aneurysms with vital SMC-rich walls. [ABSTRACT FROM AUTHOR]

Background Advances in the endovascular armamentarium, such as flow diversion and stenting devices, provide treatment options for posterior circulation intracranial aneurysms (IAs) with complex angioarchitecture. Delayed IA rupture following flow diversion is a rare but often fatal complication. Giant IAs likely pose a higher risk because of the extensive clot formation and its suspected detrimental effect on the aneurysmal wall. However, mechanisms that lead to delayed rupture are poorly understood, and few cases provide thorough documentation of macroscopic and histologic findings. Clinical Presentation After our 60-year-old patient with a giant basilar aneurysm underwent treatment with a LEO stent, the postoperative clinical course remained uneventful until day 4 when he suffered an unexpected fatal subarachnoid hemorrhage (SAH). Autopsy demonstrated extensive hemorrhage, large intraluminal thrombus, and ruptured IA wall. The aneurysm, which ruptured linearly, was completely filled with a clot that seemed to have outgrown the thin aneurysm wall. Histologic specimens revealed thinning and degenerative changes of the aneurysm's wall, and sparse neutrophilic and histiocytic inflammatory infiltrate adjacent to the rupture site, a finding consistent with recently published cases of IA rupture. Conclusions Our case report highlighting the clinical course and autopsy findings of a fatal SAH shortly after stenting this giant basilar artery aneurysm adds to the few previously reported fatal cases of IA rupture after endovascular treatment. Our macroscopic and histologic findings suggested that multimodal changes of inflammation, wall sheer tress (mechanical), and recanalization were involved. [ABSTRACT FROM AUTHOR]

Background Advances in stent-assisted coiling have incrementally expanded endovascular treatment options for complex cerebral aneurysms. After successful coil consolidation and aneurysm occlusion, endovascular scaffolds are no longer needed. Thus, bioresorbable stents that disappear after aneurysm healing could avoid future risks of in-stent thrombosis and the need for lifelong antiplatelet therapy. Objective To assess the applicability and compatibility of a bioresorbable magnesium- alloy stent (brMAS) for assisted coiling. Methods Saccular sidewall aneurysms were created in 84 male Wistar rats and treated with brMAS alone, brMAS + aspirin, or brMAS + coils + aspirin. Control groups included no treatment (natural course), solely aspirin treatment, or conventional cobalt--chromium stent + coils + aspirin treatment. After 1 and 4 weeks, aneurysm specimens were harvested and macroscopically, histologically, and molecularly examined for healing, parent artery perfusion status, and inflammatory reactions. Stent degradation was monitored for up to 6 months with micro-computed and optical coherence tomography. Results Aneurysms treated with brMAS showed advanced healing, neointima formation, and subsequent stent degradation. Additional administration of aspirin sustained aneurysm healing while reducing stent-induced intraluminal and periadventitial inflammatory responses. No negative interaction was detected between platinum coils and brMAS. Progressive brMAS degradation was confirmed. Conclusions brMAS induced appropriate healing in this sidewall aneurysm model. The concept of using bioresorbable materials to promote complete aneurysm healing and subsequent stent degradation seems promising. These results should encourage further device refinements and clinical evaluation of this treatment strategy for cerebrovascular aneurysms. [ABSTRACT FROM AUTHOR]

Background After initial subarachnoidal hemorrhage (SAH), due to an intracranial aneurysm, rebleeding is known as a factor influencing the devastating outcome. This complication has been reported to occur in ~ 4% of the patients admitted with aneurysmal SAH. Moreover, ultra-early rebleeding within the first 24 hours might occur in 9 to 17% of the cases (40-87% appearing in the first 6 hours). Risk factors influencing this situation include increasing aneurysm size, deterioration of neurologic deficits, angiography within 3 hours of bleeding, sentinel symptoms, and the loss of consciousness at initial bleeding. The aim of this retrospective study was to assess factors and potential risk factors related to rebleeding, specifically the interval from initial SAH to rebleeding. Material and Methods From a consecutive series of 243 patients who experienced aneurysmal SAH, we identified 28 patients (11.5%; 12 men, 16 women; mean age: 58 ± 10 years) who developed in-hospital rebleeding during this 49-month study (2009-2013). Demographic, radiologic, and clinical characteristics including hemodynamic parameters were analyzed. Results Rebleeding was fatal in 20 of the 28 patients (71%) and caused severe neurologic deficits (Glasgow Outcome Scale: 3; modified Rankin Scale: 5) in 3 (29%) of the remaining 8 survivors. Rebleeding occurred within the first 4 hours in 15 patients (54%) within 7, 24, and 48 hours in 17 (61%), 6 (21%), and 1 (4%) patient, respectively. In this series, the medium arterial blood pressure was 98 ± 11 mm Hg at arrival at the emergency department, 88 ĸ 10 mm Hg before rebleeding, and it dramatically increased to 124 ĸ 22 mm Hg at rebleeding. For the patients with rebleeding after aneurysmal SAH, initial sentinel headache (79%) and loss of consciousness (68%) were the common presenting symptoms. The World Federation of Neurological Societies grade was documented on admission as follows: 1-3 (n = 14 [50%]); 4-5 (n = 14 [50%]). A Fisher grade 4 was documented in 82% of the cases on the initial computed tomography (CT) scan. Overall, 42% of the cases underwent endovascular (n = 6) or microsurgical occlusion of the aneurysm (n = 6). The rest of the patients (n = 16, 58%) did not underwent occlusion of the aneurysm because of poor clinical status. Digital substraction angiography was performed in 61% of the cases. [ABSTRACT FROM AUTHOR]

Objectives: Aneurysm volume is routinely approximated calculating cylindrical volumes. Exact aneurysm volume assessment is crucial for liquid polymer embolization. The aim of this study was to compare simple cylindrical volume approximations with direct multiplanar reconstruction (MPR) segmentational volumetry in a saccular/complex experimental rabbit bifurcation aneurysm model. Methods: In 12 female New Zealand white rabbits, saccular, broad-based, bilobular, and bisaccular aneurysms (three of each) were created using the rabbit venous pouch bifurcation model. Contrastenhanced magnetic resonance angiography (CE-MRA) was performed, and maximal intensity projection (MIP) reconstructions as well as an MPR dataset were acquired. Aneurysm width and length were measured in MIP images, and the volume was approximated calculating cylindrical volumes. Threedimensional (3D) segmentational volumetry using the MPR dataset was performed in a semi-automated manner. Results: Maximal intensity projection cylindrical volumes ranged from 53.6 to 503.5 mm3 (mean 186.5±118 mm3). Multiplanar reconstruction segmentation-based volumes ranged from 74.7 to 581.0 mm3 (mean 202.2±133 mm3). The mean relative difference between MIP cylindrical and MPR segmentation volume calculation was 24.7% (range 277.5 to z50.8%). Only 4 of 12 MPR segmentational volumes were within a 10% range of results calculated for MIP cylindrical volume, and 3 of those were in broad-based aneurysms. Conclusion: This descriptive study demonstrates that estimated MIP cylindrical volumes differ from those measured by MPR segmentation volumetry. With the increasing acquisition of 3D data as 3D-MRA and the increasing need for exact volume determination, studies on the accuracy of computational segmentational volumetry of CE-MRA are necessary. [ABSTRACT FROM AUTHOR]