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Background: Hemodynamic factors are believed to be closely related to IA growth. However, the underlying pathophysiological mechanism that induces the growth sequence in tandem intracranial aneurysms (IAs) remains unclear. Methods and results: This study involved five patients with tandem IAs. Aneurysm models were reconstructed based on image datasets. A novel vascular restoration algorithm was proposed to generate the hypothetical geometry of the healthy parent vessel before each IA formation in the concatenated structure. Detailed hemodynamic patterns and morphological features were revealed under various growth sequences of tandem IAs to investigate the flow-driven mechanism of IA growth. Potential hemodynamic indicators of IA formation were proposed. Results: The patient cases were divided into two groups based on the size difference of tandem IAs. In the group with a similar size of tandem IAs, the position of the vortex core was associated with the site of the secondary aneurysm, while in the group with a significant size difference of the IAs, the position with the maximum curvature of the parent vessel plays a significant role in aneurysm formation. Conclusions: This study preliminarily revealed key hemodynamic and morphological indicators that determine the formation of tandem IAs. The proposed vascular restoration algorithm that provided the pre-aneurysm vasculature might be useful in investigating the flow-driven mechanism of IA growth, thus contributing to the risk evaluation of secondary aneurysm formation. [ABSTRACT FROM AUTHOR]

Tandem intracranial aneurysms (TandIAs) are rare but inherently complex, and special technical considerations are required for their surgical management. The present case highlights the key surgical aspects of two carotid-ophthalmic TandIAs incidentally found in a 60-year-old female. Both the aneurysms were superiorly projecting, regular in size, and involved the left ophthalmic segment of the internal carotid artery (ICA). The minimum distance between the necks was 3 mm. The patient underwent microsurgery because of the reported major complications rate of the endovascular treatment in the case of a very short minimum distance between the TandIAs. After cervical ICA exposure, both the aneurysms were excluded through a pterional approach. Intradural anterior clinoidectomy and unroofing of the optic canal allowed the mobilization of the left optic nerve. The more distal aneurysm was clipped before the opening of the distal dural ring of the ICA. The proximal aneurysm was clipped with two straight clips stacked perpendicular to the ICA. A small remnant was intentionally left to avoid the stenosis of the ophthalmic artery. Postoperative angiography showed the exclusion of both the aneurysms with a small dog-ear of the more proximal one. The patient was discharged neurologically intact and, after one year, the remnant remained stable. Microsurgical clipping is a definitive and durable treatment for carotid-ophthalmic TandIAs. In the case of a very short minimum distance between the aneurysms, the distal one should be clipped first to make the anterior clinoidectomy, opening of the distal dural ring of the ICA, and clipping of the more proximal aneurysm easier. [ABSTRACT FROM AUTHOR]

Background: Tandem aneurysms (TAs) are a distinct type of multiple intracranial aneurysms (IAs), the treatment strategies for which remain controversial. We aimed to reveal the clinical and angiographic outcomes of endovascular treatment as well as their risk factors in these complex multiple IAs. Methods: This multicenter, retrospective follow-up study was carried out in 3 hospitals in China. In total, clinical and angiographical data of 137 patients with 145 lesions (7 patients had bilateral lesions) and 315 TAs were collected. The treatment strategies were divided into full or partial treatment, single- or multiple-session treatment, and coiling (including single coiling and stent-assisted coiling)- or flow-diverting stent (FDS) treatment. Perioperative complications, as well as angiographic and clinical outcomes and their risk factors, were analyzed using univariate analysis and a multiple regression model. Results: Of treated TA lesions, 17 (16.0%) perioperative complications were found. Significant differences were found between the single- and multiple-session treatment groups (p = 0.012). At the latest follow-up, there were no significant differences in the modified Raymond Scale scores between different treatment groups. Significant differences were found in the embolization degree between the coiling and FDS groups (p = 0.038) and between the single common stent (without coiling) and the other treatment groups (p < 0.001). In IAs managed by a single LVIS stent (without coiling), 60% achieved improved or completed occlusion. Multivariate regression analysis found that a shorter minimum distance (odds ratio [OR] 5.967, 95% confidence interval [CI] 1.366–26.074; p = 0.018), multiple-session treatment (OR 9.961, 95% CI 1.707–58.127; p = 0.011), and diabetes (OR 8.106, 95% CI 1.928–34.084; p = 0.004) were predictors of perioperative complications, while shorter minimum distance (OR 5.619, 95% CI 1.493–21.152; p = 0.011), greater diameter ratio (OR 3.621, 95% CI 1.014–12.937; p = 0.048), and greater size ratio (OR 2.424, 95% CI 1.007–5.834; p = 0.048) were predictors of low completed occlusion rate. Conclusions: Both coiling and FDS can be utilized safely and can achieve similar clinical outcomes. FDS and LVIS are recommended for IAs that do not require embolization but cannot be prevented from being covered by stents. A multiple-session treatment may increase the treatment risk, and the minimum distance may affect the incidence of perioperative complications and completed occlusions. Further hemodynamic and prospective studies on such TAs in close proximity to one another are needed. [ABSTRACT FROM AUTHOR]