Bailout Strategies and Complications Associated with the Use of Flow-Diverting Stents for Treating Intracranial Aneurysms

Safety and effectiveness assessment of the surpass evolve (SEASE): a post-market international multicenter study

BACKGROUND

Flow diverters are the first-line treatment for specific intracranial aneurysms (iA). Surpass Evolve (SE) is a new-generation 64-wire flow diverter with a high braid angle. Current literature on the SE is limited. We aimed to report the first international real-world experience evaluating the safety and effectiveness of the SE.

METHODS

The Safety and Effectiveness Assessment of the Surpass Evolve (SEASE) was a multicenter retrospective international post-marketing cohort study including consecutive patients treated with SE for iAs between 2020 and 2022. Demographic, clinical, and angiographic data were collected. Primary effectiveness was independent core lab adjudicated complete occlusion rates (Raymond-Roy Class 1) at last follow-up. Primary safety were major ischemic/hemorrhagic events and mortality.

RESULTS

In total, 305 patients with 332 aneurysms underwent SE implantation. The patients had a median age of 59 [50-67] years, and 256 (83.9%) were female. The baseline modified Rankin scale score was 0-2 in 291 patients (96.7%). Most aneurysms were unruptured (285, 93.4%) and saccular (309, 93.1%). Previous treatment was present in 76 (22.9%) patients. The median aneurysm size was 5.1 [3.4-9.0] mm, and the median neck width was 3.6 [2.7-5.1] mm. Most aneurysms were in the internal carotid artery C6 ophthalmic segment (126, 38.0%), followed by the communicating segment (58, 17.5%). At median 10.2 [6.4-12.9] months follow-up, 233 (73.0%) aneurysms achieved complete occlusion. After adjusting for confounders, complete occlusion remained consistent. Major stroke and procedure-related mortality were reported in 6 (2%) and 2 (0.7%) cases, respectively.

CONCLUSION

These results demonstrate that SE has a consistently high effectiveness and favorable safety for the treatment of iAs.

Stent retriever expansion as a corrective maneuver to optimize inadequately deployed flow diverter stents

BACKGROUND AND PURPOSE

As flow diversion (FD) is becoming increasingly important in the endovascular treatment of intracranial aneurysms, the rate of technical complications is also increasing. Inadequate FD implantation may lead to both ischemic complications and decreased treatment efficacy. The aim of this study was to evaluate the efficacy of off-label stent retriever (SR) use in managing technical complications associated with FD implantation.

MATERIALS AND METHODS

A retrospective analysis of data from patients who underwent FD treatment at two neuroradiology centers was performed. The objective was to identify cases in which the FD was inadequately deployed and SR expansion was performed as a corrective maneuver. The analysis included anatomic characteristics, technical information, angiographic and clinical outcomes, and complications.

RESULTS

A total of 35 corrective maneuvers with SR were performed in 25 FD treatments. The corrective maneuvers in all treatments were successful, and no additional devices or therapies were required. No procedural complications or technical difficulties were documented.

CONCLUSION

With the growing role of FDs in neurointerventional treatment, familiarity with corrective maneuvers after technical complications or inadequate implantation is important. The findings in our selected cohort demonstrated that SR expansion is an effective and safe corrective maneuver for incompletely opened FDs.

Serial VerifyNow P2Y12 platelet reactivity units in cerebral aneurysm patients treated with ticagrelor surrounding stent-coiling or flow diversion

INTRODUCTION

Platelet function testing using serial VerifyNow P2Y12 platelet reactivity units (PRUs) is established for guiding clopidogrel antiplatelet therapy in cerebral aneurysm stenting procedures. However, for ticagrelor, the impact of serial PRU testing and the identification of safe PRU ranges remains unexplored.

METHODS

Flow diversion stenting (n = 232) and stent-assisted coiling procedures (n = 83) performed 05/2017-12/2021 were reviewed. Out of these, 31 flow diversion and 18 stent-coiling procedures were performed on 44 patients using ticagrelor. Baseline demographics, ticagrelor PRUs, and clinical outcomes were assessed.

RESULTS

Collectively, 257 ticagrelor P2Y12 PRUs were obtained. PRUs were <100 in 192/257 (74.7%) tests. Only 11/257 (4.3%) PRUs were >200. The overall median ticagrelor PRU was 38 (IQR 11-101). Among the 49 procedures, median PRUs before the procedure (25, IQR 10-67), on the day of the procedure (68, IQR 44-117), and on the day after the procedure (37, IQR 21-79) did not show the significant differences between the groups. A total of seven thromboembolic complications occurred. Median PRUs surrounding the thromboembolic complications (median 182, IQR 148-235) were significantly higher than preprocedural (p < .001), day of surgery (p < .01), and postprocedural PRUs (p < .01). All seven procedures harbored demographic, anatomic, or procedural features increasing the risk for thromboembolic complications.

DISCUSSION

The majority of periprocedural ticagrelor PRUs were <100. PRUs at the time point of thromboembolic complications were >120. Despite procedure-complicating features in each thromboembolic case, it raises the question whether safe ticagrelor PRU levels might be lower than those commonly applied for clopidogrel.

Advancements in Brain Aneurysm Management: Integrating Neuroanatomy, Physiopathology, and Neurosurgical Techniques

Brain aneurysms, characterized by abnormal bulging in blood vessels, pose significant risks if ruptured, necessitating precise neuroanatomical knowledge and advanced neurosurgical techniques for effective management. This article delves into the intricate neuroanatomy relevant to brain aneurysms, including the vascular structures and critical regions involved. It provides a comprehensive overview of the pathophysiology of aneurysm formation and progression. The discussion extends to modern neurosurgical approaches for treating brain aneurysms, such as microsurgical clipping, endovascular coiling, and flow diversion techniques. Emphasis is placed on preoperative planning, intraoperative navigation, and postoperative care, highlighting the importance of a multidisciplinary approach. By integrating neuroanatomical insights with cutting-edge surgical practices, this article aims to enhance the understanding and treatment outcomes of brain aneurysms.

Effectiveness of Flow Diverter Stents in the Treatment of Intracranial Aneurysms: Single-Center 10-Year Results

Purpose This study's objective was to show how effectively flow-diverting stents work when treating cerebral aneurysms. The assessment aimed to determine efficaciousness related to aneurysm type, size, and location as well as early- and late-term results. Material and method The study included 153 aneurysms from 122 patients treated in interventional radiology unit with flow diverter stents between July 2010 and June 2020. Apart from demographic data, size, type, and location of aneurysms; technical success, peri, post-procedural, and late complications; aneurysm occlusion rates, morbidity and mortality rates were extracted from patient records. Results This study enrolled 90 (73.8%) females and 32 (26.2%) males; average age of the patients was 52.8±12.9. The average follow-up period was 33.4±9.9 months. The most common type of aneurysm was saccular (133; 86.9%), and the most common location was the supraclinoid segment with 67 (43.8%). Complete occlusion was observed in 115 of 140 aneurysms from 110 patients during follow-up. No statistically significant difference was detected between the sizes and types of aneurysms and complete occlusion rates (p=0.096, p=0.583). The total occlusion rate was found to be significantly higher in internal carotid artery (ICA) supraclinoid segment aneurysms compared to other locations (p = 0.006). During the follow-up period, flow diverter stent-related permanent morbidity was observed in four (3.6%) patients and mortality was observed in five (4.5%) patients. Conclusion Flow diverter stents can be successfully applied to many aneurysm types, from small aneurysms to large and giant aneurysms, and have high aneurysm occlusion rates with low morbidity and mortality. By the aspects of the current study the total occlusion rate was found to be significantly higher in ICA supraclinoid segment aneurysms compared to other localizations.

Endovascular Rescue of Previously Treated Carotid Aneurysm: Higher Radial Force 48-Wire Flow Diverter for Salvage of Collapsed 64-Wire Device With Braid Deformation: 2-Dimensional Operative Video

Aneurysm treatment presents various therapeutic options. Flow diverters (FD) stents are a revolutionizing endovascular technique for previously untreatable aneurysms.1 FD stents have documented success rates up to 95% and complication rates as low as 2.3%.2 This modality has proven its effectiveness and safety, but it is critical to consider potential complications. Complications include vascular-related problems such as perforation, occlusion, cerebral hyperperfusion, stent thrombosis, restenosis, and embolic events.3 To date, there is no standardized definition for braid collapse and fish-mouthing; however, braid collapse has been reported to occur at a rate of 1% and the latter at a rate of 3%.4 This technical video presents a case of a 51-year-old woman initially treated with a Surpass Evolve flow diverter (Stryker) for a right ophthalmic aneurysm. Secondary to device malapposition and collapse, she developed recurrent ischemic progressive neurologic impairment symptoms. The braid collapse was treated using a Pipeline Embolization device 3.25 × 20 mm (Medtronic) because this device exhibited a larger partial compressive force when compared with the 64-wire device.5 The procedure was uneventful and significantly improved the patient's neurologic symptoms. This technical video illustrates rescue stenting as a salvage intervention for FD collapse cases. The patient gave informed consent for surgery. Institutional review board approval was deemed unnecessary.

Quantitative analysis of hemodynamic changes induced by the discrepancy between the sizes of the flow diverter and parent artery

The efficacy of flow diverters is influenced by the strut configuration changes resulting from size discrepancies between the stent and the parent artery. This study aimed to quantitatively analyze the impact of size discrepancies between flow diverters and parent arteries on the flow diversion effects, using computational fluid dynamics. Four silicone models with varying parent artery sizes were developed. Real flow diverters were deployed in these models to assess stent configurations at the aneurysm neck. Virtual stents were generated based on these configurations for computational fluid dynamics analysis. The changes in the reduction rate of the hemodynamic parameters were quantified to evaluate the flow diversion effect. Implanting 4.0 mm flow diverters in aneurysm models with parent artery diameters of 3.0-4.5 mm, in 0.5 mm increments, revealed that a shift from oversized to undersized flow diverters led to an increase in the reduction rates of hemodynamic parameter, accompanied by enhanced metal coverage rate and pore density. However, the flow diversion effect observed transitioning from oversizing to matching was less pronounced when moving from matching to undersizing. This emphasizes the importance of proper sizing of flow diverters, considering the benefits of undersizing and not to exceed the threshold of advantages.

Prasugrel Single Antiplatelet Therapy versus Aspirin and Clopidogrel Dual Antiplatelet Therapy for Flow Diverter Treatment for Cerebral Aneurysms: A Retrospective Multicenter Study

BACKGROUND AND PURPOSE

The optimal antiplatelet regimen after flow diverter treatment of cerebral aneurysms is still a matter of debate. A single antiplatelet therapy might be advantageous in determined clinical scenarios. This study evaluated the efficacy and safety of prasugrel single antiplatelet therapy versus aspirin and clopidogrel dual antiplatelet therapy.

MATERIALS AND METHODS

We performed a post hoc analysis of 4 retrospective multicenter studies including ruptured and unruptured aneurysms treated with flow diversion using either prasugrel single antiplatelet therapy or dual antiplatelet therapy. Primary end points were the occurrence of any kind of procedure- or device-related thromboembolic complications and complete aneurysm occlusion at the latest radiologic follow-up (mean, 18 months). Dichotomized comparisons of outcomes were performed between single antiplatelet therapy and dual antiplatelet therapy. Additionally, the influence of various patient- and aneurysm-related variables on the occurrence of thromboembolic complications was investigated using multivariable backward logistic regression.

RESULTS

A total of 222 patients with 251 aneurysms were included, 90 (40.5%) in the single antiplatelet therapy and 132 (59.5%) in the dual antiplatelet therapy group. The primary outcome-procedure- or device-related thromboembolic complications-occurred in 6 patients (6.6%) of the single antiplatelet therapy and in 12 patients (9.0%) of the dual antiplatelet therapy group (P = .62; OR, 0.712; 95% CI, 0.260-1.930). The primary treatment efficacy end point was reached in 82 patients (80.4%) of the single antiplatelet therapy and in 115 patients (78.2%) of the dual antiplatelet therapy group (P = .752; OR, 1.141; 95% CI, 0.599-2.101). Logistic regression showed that non-surface-modified flow diverters (P = .014) and fusiform aneurysm morphology (P = .004) significantly increased the probability of thromboembolic complications.

CONCLUSIONS

Prasugrel single antiplatelet therapy after flow diverter treatment may be as safe and effective as dual antiplatelet therapy and could, therefore, be a valid alternative in selected patients. Further prospective comparative studies are required to validate our findings.

Long-term Follow-up After Aneurysm Treatment with the Flow Redirection Endoluminal Device (FRED) Flow Diverter

INTRODUCTION

This study focuses on long-term outcomes after aneurysm treatment with either the Flow Re-Direction Endoluminal Device (FRED) or the FRED Jr. to investigate the durability of treatment effect and long-term complications.

METHODS

This study is based on a retrospective analysis of a prospectively maintained patient data base. Patients treated with either FRED or FRED Jr. between 2013 and 2017 at our institution, and thus a possibility for ≥ 5 years of follow-up, were included. Aneurysm occlusion rates, recurrence rates, modified Rankin scale score shifts to baseline, and delayed complications were assessed.

RESULTS

In this study 68 patients with 84 aneurysms had long-term follow-up with a mean duration of 57.3 months and 44 patients harboring 52 aneurysms had a follow-up ≥ 5 years with a mean follow-up period of 69.2 months. Complete occlusion was reached in 77.4% at 2 years and increased to 84.9% when the latest available imaging result was considered. Younger age and the absence of branch involvement were predictors for aneurysm occlusion in linear regression analysis. After the 2‑year threshold, there were 3 reported symptomatic non-serious adverse events. Of these, one patient had a minor stroke, one a transitory ischemic attack and one had persistent mass effect symptoms due to a giant aneurysm, none of these resulted in subsequent neurological disability.

CONCLUSION

This long-term follow-up study demonstrates that the FRED and FRED Jr. are safe and effective for the treatment of cerebral aneurysms in the long term, with high rates of complete occlusion and low rates of delayed adverse events.

Low-Profile Visualized Intraluminal Support Junior Flow-Diversion Properties Used for Stabilization of a Superior Cerebellar Artery Pseudoaneurysm

BACKGROUND

Pseudoaneurysms of the posterior circulation pose a unique management challenge. The fragile nature of the pseudoaneurysm wall presents a high risk of rupture and demands treatment. Small vasculature, particularly distal in the posterior circulation, can preclude management with traditional flow diverters, where the alternative of vessel sacrifice is unacceptable. Small stents can have flow-diversion properties and can be used in these high-risk, difficult-to-access aneurysms.

METHODS

We describe a 40-year-old woman presenting with a ruptured dissecting right superior cerebellar artery pseudoaneurysm after minor trauma. Given the aneurysm's small size and morphology, it was not amenable to coiling and parent vessel sacrifice was potentially morbid. The pseudoaneurysm was initially stabilized with a Low-Profile Visualized Intraluminal Support Junior (LVIS Jr.) stent due to its reported flow-diverting properties.

RESULTS

At six-month follow-up the pseudoaneurysm was stable and the vasospasm had resolved. At this point, definitive treatment with a "FRED Jr." (Flow Re-Direction Endoluminal Device Junior) flow diverter was pursued. Complete obliteration of the pseudoaneurysm was seen at 12 months' follow-up after staged treatment.

CONCLUSIONS

Due to the unique challenges associated with ruptured pseudoaneurysms located on small-caliber vessels, the options for definitive treatment are limited. The small size of the LVIS Jr. stent and its flow-diverting properties make it a practical treatment option in a difficult situation. This case report provides further support for the flow-diverting properties of the LVIS Jr. and its potential application in the treatment of ruptured pseudoaneurysms in small-caliber intracranial vessels.

Management of giant internal carotid aneurysm by extracranial-intracranial bypass and flow diverter stent

Flow diverter stents have become the standard approach to managing intracranial aneurysms; however, in some cases of complex, wide-necked aneurysms, poor outcomes due to stent occlusion have been reported. We report the case of a giant internal carotid artery aneurysm treated by high-flow extracranial-intracranial (EC-IC) bypass with flow diverter deployment. Seven months post-operatively, radiographic imaging demonstrated occlusion of the stent and parent artery, with further ischemic events prevented by collateral flow from the high flow bypass. This case demonstrates the continued utility of EC-IC bypass in the endovascular era, especially as a rescue tool in cases of delayed stent occlusion.

Surpass embolization of intracranial aneurysms: Perspective from a 2-year longitudinal follow-up study across high volume comprehensive stroke centers

BACKGROUND

Surpass Streamline (SS; Stryker^©) is an over-the-wire first-generation flow diverter (FD). There is a scarcity of data on real-world outcomes and complications of this FD.

METHODS

A retrospective review of consecutive cases between January 2019 and July 2021 at two high-volume comprehensive stroke centers, involving SS was conducted.

RESULTS

Fifty-five patients harbored 69 treated aneurysms, of which 96% were in the internal carotid petrous to terminus segments and 88% were <10 mm in size, and 12% measuring 10-24 mm. Raymond Roy Grade 1 occlusion was noted in 55 aneurysms (79.7%) at 1 year. Median follow-up duration was 26 months (mean = 26.06). Major complications were seen in eight patients (14.5%; 95% CI 6.5-26.7) and mortality attributable to SS stenting complications occurred in two (4.3%) patients. Four (7.2%) had ophthalmologic thromboembolic complications and two had (3.6%) ischemic complications. Procedural complications occurred in 10 patients (18.18%; 95% CI 9.1-30.9). Technical complications during procedure (n = 3, 5.3%) were: "confirmed" distal middle cerebral artery (MCA) guidewire perforation; "suspected" distal MCA guidewire perforation causing post-procedural subarachnoid hemorrhage and internal carotid artery dissection causing ischemic stroke. Seizures were seen in 5 (9.09%) and carotid-cavernous fistula in 1 (1.8%). Multivariate regression analysis showed technical challenges significantly predicted occurrence of major complications (p = 0.001; R²= 0.39, F(13,43) = 2.15, p = 0.029). Univariate analysis showed technical challenges significantly predicted ophthalmological complications (R²= 0.06, F(1,55) = 4.04, p = 0.049) and major complications (R²= 0.21, F(1,55) = 15.11, p = 0.0002).

CONCLUSION

Large-scale future registry should focus on national data regarding SS safety, technical challenges, and procedural complications. We present one of the longest follow-ups for SS in literature.

Comaneci stent-angioplasty for the optimization of inadequately deployed flow diverter stents

BACKGROUND AND PURPOSE

In endovascular procedures, inadequate deployment of a flow diverter stent is a highly concerning technical complication that can lead to acute parent vessel occlusion and ischaemic events. This study aimed to assess the off-label use of the Comaneci device in managing technical difficulties associated with flow diversion.

MATERIALS AND METHODS

We conducted an analysis of all flow diverter procedures documented in our prospectively collected database. Our objective was to identify patients with inadequately deployed implants who underwent Comaneci stent-angioplasty. Both Comaneci 17 and Comaneci 21 devices were utilized to address and remediate technical complications related to stent deployment. We reviewed anatomical features, technical details, intraprocedural complications, as well as clinical and angiographic outcomes.

RESULTS

Thirty-one Comaneci devices were employed to remediate 31 inadequately deployed flow diverter stents. Successful resolution of technical complications associated with flow diverter placement was achieved in all attempted cases. No clinically significant complications were attributed to the technique, and no mortality was observed during the study.

CONCLUSION

Technical issues arising from flow diverter stent deployment are formidable complications. Familiarity with appropriate corrective manoeuvres is essential to achieve successful outcomes. The Comaneci device can be safely and effectively incorporated into the range of techniques used to rectify inadequately deployed stents.

The Rationale Behind Transcirculation Neuroendovascular Interventions: Literature Review Through a Case-Series Approach

BACKGROUND

With the development of advanced endovascular techniques and materials, neurointerventionalists can perform challenging and complex cases that were previously difficult to perform. Transcirculation approaches could be a useful tool used in complicated cases, providing access to the target vessel, through the contralateral or opposite circulation, when anterograde access is difficult or nonachievable.

OBJECTIVE

To retrospectively review cerebrovascular interventions performed through a transcirculation approach performed by staff at our Institution.

METHODS

English-language studies, published until August 2022, reporting transcirculation interventions in the cerebrovascular circulation were retrospectively collected. Type of intervention, number of cases, rationale, and complications were analyzed. Furthermore, similar cases performed by staff currently at our institution were also reviewed and described.

RESULTS

Including our cases, a total of 273 transcirculation treatment approaches have been reported. Intracranial aneurysm embolization, stroke thrombectomies, intra-arterial ophthalmic chemotherapy, arteriovenous malformationss, arteriovenous fistulas embolizations, and intracranial angioplasty and stenting are common indications. Reason for using a retrograde approach were stent/balloon-assisted coiling of wide neck aneurysm in 116 cases, difficult angulation of branch in 91 cases, occlusion of parent vessel in 55 cases, and bailout/other in 11 cases.

CONCLUSION

Transcirculation approaches can be considered for cases where conventional anterograde treatment options are not feasible or as a bailout strategy in failed or complicated treatment attempts. They represent a strategy to consider when facing challenging cases, and if performed by experienced and dedicated neurointerventionalists, they can represent a safe alternative.

Fluoroscopy, CT, and MR imaging characteristics of a novel primarily bioresorbable flow-diverting stent for aneurysms

BACKGROUND

Five to ten percent of the global population have unruptured intracranial aneurysms, and ruptured brain aneurysms cause approximately 500,000 deaths a year. Flow-diverting stent treatment is a less invasive intracranial aneurysm treatment that induces aneurysm thrombosis. The imaging characteristics of a novel primarily bioresorbable flow-diverting stent (BFDS) are assessed in comparison to the leading metal stent using fluoroscopy, CT, and MRI.

METHODS

X-ray/fluoroscopic images of stents were taken using a human cadaveric skull model. CT and MRI were acquired using silicone flow models of residual aneurysms. Images were analyzed with Likert scales in anonymous surveys by neurointerventionalists. Quantitative measurements of radiographic density (CT) and artifact boundary size (CT & MRI) were also obtained.

RESULTS

Visibility of the BFDS on X-ray was less than the metal stent but deemed adequate for deployment and intraprocedural assessment. The metal stent was more radiopaque than the BFDS on CT, but qualitative assessment was not significantly different for the two stents. MRI imaging was significantly better using the BFDS in terms of overall artifact and intraluminal assessment.

CONCLUSIONS

The BFDS has adequate visualization on X-ray/fluoroscopy and should be clinically acceptable for fluoroscopic deployment. On MRI, there is less quantitative artifact as well as overall improved qualitative assessment that will allow for more detailed non-invasive imaging follow-up of treated aneurysms, potentially reducing the need for digital subtraction catheter angiography.

Acute Intraprocedural Thrombosis After Flow Diverter Stent Implantation: Risk Factors and Relevance of Standard Observation Time for Early Detection and Management

PURPOSE

Acute intraprocedural thrombosis (AIT) is a severe complication of flow diverter stent (FDS) implantation for the treatment of intracranial aneurysms. Even though device-related thromboembolic complications are well known, there are no acknowledged risk factors nor defined surveillance protocols for their early detection. This study aimed to demonstrate that an angiographic active surveillance is effective to detect and treat AIT. Furthermore, we investigated risk factors for the occurrence of AIT.

METHODS

A prospective institutional protocol consisting of a defined observation period of 30 min following FDS deployment was established to detect AIT. Overall incidence, as well as the efficacy and safety of AIT treatment were assessed. Moreover, radiological and clinical outcomes of patients with AIT were analyzed. The influence of various patient- and procedure-related factors on the occurrence of AIT was investigated using multivariable forward logistic regression.

RESULTS

During active surveillance twelve cases of AIT were observed among a total of 161 procedures (incidence: 7.5%). The median time of first observation was 15.5 min (IQR 9.5) after FDS implantation. The early recognition of AIT ensured a prompt treatment with intravenous application of a glycoprotein IIb/IIIa inhibitor, which led to complete thrombus resolution in all cases without hemorrhagic complications. Patients with pre-existing arterial hypertension and side branches originating from the aneurysmal sac had a higher risk of AIT (respectively OR, 9.844; OR, 3.553). There were two cases of re-thrombosis in the short-term postoperative period, of whom one died. The remaining patients with AIT had a good clinical outcome.

CONCLUSION

Active surveillance for 30 min after FDS implantation is an effective strategy for early detection and ensuing treatment of AIT and can thus prevent secondary sequalae. Hypertension and side branches originating from the aneurysmal sac may increase the risk of AIT.

Progressive volume reduction and long-term aneurysmal collapse following flow diversion treatment of giant and symptomatic cerebral aneurysms

Background

The primary goal of conventional endovascular and microvascular approaches is the clinical and radiological resolution of the symptomatic aneurysm-induced mass effect. This study assessed the volume changes and mass effect reduction due to sac shrinkage after treatment with flow diverter stents (FD) for unruptured cerebral aneurysms.

Methods

We analyzed retrospectively 36 symptomatic aneurysms that were larger or equal to 25 mm in diameter in patients treated at our center from January 2016 to April 2022. Radiological and clinical outcomes were analyzed, including aneurysmal volume changes and resolution of aneurysm-related symptoms.

Results

At 6 months, 25 aneurysms decreased in size, 2 remained unchanged, and 9 aneurysms demonstrated a post-treatment dimensional increase. At 12 months, 30 aneurysms showed a progressive radiological volume reduction. Either no change or negligible shrinkage was observed in the remaining six aneurysms. At 24 months, 32 aneurysms showed aneurysmal shrinkage by a mean 47% volume loss with respect to baseline. At the last follow-up, all 13 patients who had presented with third cranial nerve palsy showed improvements. Complete reversal of the pretreatment edematous changes was confirmed in all cases. The overall post-treatment complication rate was 8.3%, as 3 patients experienced non-fatal delayed rupture of their aneurysm. There was no mortality in this study.

Conclusion

Flow diversion could effectively induce progressive aneurysmal shrinkage and resolution of the mass effect associated with giant symptomatic cerebral aneurysms.

Imaging Intracranial Aneurysms in the Endovascular Era: Surveillance and Posttreatment Follow-up

While most intracranial aneurysms (IAs) remain asymptomatic over a patient's lifetime, those that rupture can cause devastating outcomes. The increased usage and quality of neuroimaging has increased detection of unruptured IAs and driven an increase in surveillance and treatment of these lesions. Standard practice is to treat incidentally discovered unruptured IAs that confer high rupture risk as well as ruptured IAs to prevent rehemorrhage. IAs are increasingly treated with coil embolization instead of microsurgical clipping; more recently, flow diversion and intrasaccular flow disruption have further expanded the versatility and utility of endovascular IA treatment. Imaging is increasingly used for posttreatment IA follow-up in the endovascular era. While cerebral angiography remains the standard for IA characterization and treatment planning, advances in CT and CT angiography and MR angiography have improved the diagnostic accuracy of noninvasive imaging for initial diagnosis and surveillance. IA features including size, dome-to-neck ratio, location, and orientation allow rupture risk stratification and determination of optimal treatment strategy and timing. The radiologist should be familiar with the imaging appearance of common IA treatment devices and the expected imaging findings following treatment. In distinction to clipping and coil embolization, flow diversion and intrasaccular flow disruption induce progressive aneurysm obliteration over months to years. Careful assessment of the device; the treated IA; adjacent brain, bone, meninges; and involved extracranial and intracranial vasculature is crucial at posttreatment follow-up imaging to confirm aneurysm obliteration and identify short-term and long-term posttreatment complications. An invited commentary by Chatterjee is available online. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ^©RSNA, 2022.

Flow diversion for acutely ruptured intracranial aneurysms treatment: A retrospective study and literature review

OBJECTIVE

Flow diversion is becoming an increasingly established practice for the treatment of acutely ruptured intracranial aneurysms. In this study the authors present a literature review and meta-analysis, adding a retrospective review of institutional registry on emergency treatment of aRIA with flow diverter stent.

MATERIALS AND METHODS

A systematic search of PubMed, SCOPUS, Ovid MEDLINE, and Ovid EMBASE was performed on April 20^th, 2021, extrapolating 35 articles. R language 'meta' and 'metafor' packages were used for data pooling. The DerSimonian-Laird model was used to calculate the pooled effect. The I² value and Q statistic evaluated study heterogeneity. Additionally, the authors retrospectively reviewed their institutional database for the treatment and outcomes of all patients with acutely ruptured intracranial aneurysms treated with flow diverter stent placement from May 2010 to November 2020 was performed.

RESULTS

From the systematic literature review and meta-analysis, the pooled proportion of complete aneurysm occlusion was 78%, with a pooled rate of 79%, 71%, 80%, and 50% for dissecting, saccular, fusiform, and mycotic aneurysms, respectively. The pooled proportion of aneurysm rebleeding and intrastent stenosis was 12% and 15% respectively, for a total of 27% rate. The analysis of authors retrospective register showed an overall mortality rate of 16.7% (3/18), with a low but not negligible postprocedural rebleeding and intrastent thrombosis rates (5.6% and 11.1% respectively).

CONCLUSION

Although increasingly utilized in the management of selected patients with acutely ruptured intracranial aneurysms, flow diversion for acutely ruptured intracranial aneurysms treatment presents rebleeding and intrastent stenosis rates not negligible.

Triggering of Carotid Sinus Reflex during Deployment of the Flow-diverter Device

The carotid sinus reflex (CSR) is a rare complication of the Pipeline Embolization Device (PED) deployment. No study has assessed the potential risk factors in a case series. The purpose of this study was to examine CSR triggering during PED deployment. Thirty-seven consecutive patients who underwent PED deployment were included. All procedures were performed under local anesthesia with mild sedation. We retrospectively analyzed patient characteristics, PED deployment time, and vital signs during the procedure. The vital signs included the pulse rate (PR) and systolic blood pressure (SBP) obtained at three timepoints (pre-deployment, during deployment, post-deployment). We examined the triggering of the CSR during PED deployment by comparing the vital signs at the three timepoints. Moreover, risk factors for CSR were analyzed with univariate analysis. The patients’ average age was 66.3 years. The average size of the aneurysm was 18.0 mm. Six patients (16.2%) showed a decline in the SBP or PR defined as CSR. One patient had a transient cardiac arrest and two had severe transient bradycardia. Deployment into the ophthalmic segment of the internal carotid artery (C2 segment) aneurysm (p = 0.022), prolonged PED deployment time more than 14.5 minutes (p = 0.005), and an acute angle of the anterior genu less than 51.5 degrees (p = 0.005) were risk factors in triggering CSR. CSR may be triggered during PED deployment under local anesthesia with mild sedation. Deployment to the C2 segment aneurysm, prolonged PED deployment time, and an acute angle of the anterior genu were associated with CSR triggering.

Bailout stentectomy of 47 self-expandable intracranial stents

Background

Self-expanding stents are increasingly being deployed for stent-assisted coiling or flow diversion of intracranial aneurysms. Complications related to stent misbehavior may arise, however, including lack of expansion, device displacement, or parent vessel thrombosis. We present our experience of various stent removal techniques (stentectomy) with a focus on technical and clinical outcomes.

Methods

Stentectomy was attempted either with a single device, including the Alligator, Microsnare, or Solitaire, or by combining a Microsnare with a second device. Dual techniques included in this report are the Snare-over-Stentretriever technique we developed using a Microsnare and a Solitaire, and the previously described Loop-and-Snare technique using a Microsnare and a microwire. The technical success and complication rate, as well as the clinical outcome using the mRS were analyzed.

Results

Forty-seven stentectomies were attempted in 36 patients treated for 37 aneurysms. Forty-two devices (89.3%) were successfully retrieved. Single-device stentectomy was successful in 34% of cases, compared with 74% with dual-device techniques. Of the 20 patients with a thrombosed parent or efferent vessel, 17 were successfully recanalized using stentectomy. All successful stentectomy patients made a clinically uneventful recovery, except one with a minor postoperative stroke (mRS 1 at discharge). Failed stentectomy was associated with major ischemic stroke in two patients and death in one patient. There were no stentectomy-related vessel perforations or dissections.

Conclusion

While various single devices can be used to safely retrieve dysfunctional intracranial self-expandable stents, dual-device techniques are more than twice as effective, according to our experience.

Management of Small Unruptured Intracranial Aneurysms: To Treat or Not to Treat?

Unruptured intracranial aneurysms measuring <7 mm in diameter have become increasingly prevalent due to advances in diagnostic imaging. The most feared complication is aneurysm rupture leading to a subarachnoid hemorrhage. Based on the current literature, the 3 main treatments for an unruptured intracranial aneurysm are conservative management with follow-up imaging, endovascular coiling, or surgical clipping. However, there remains no consensus on the best treatment approach. The natural history of the aneurysm and risk factors for aneurysm rupture must be considered to individualize treatment. Models including population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from a prior aneurysm, site of aneurysm score, Unruptured Intracranial Aneurysm Treatment Score, and advanced neuroimaging can assist physicians in assessing the risk of aneurysm rupture. Macrophages and other inflammatory modulators have been elucidated as playing a role in intracranial aneurysm progression and eventual rupture. Further studies need to be conducted to explore the effects of therapeutic drugs targeting inflammatory modulators.

Endovascular Treatment of a Traumatic Middle Cerebral Artery Pseudoaneurysm with the Pipeline Flex Embolization Device

OBJECTIVE

Traumatic pseudoaneurysms of the proximal middle cerebral artery (MCA) segments are challenging to treat. We describe the management of traumatic internal carotid artery and MCA pseudoaneurysms with flow diversion.

CASE DESCRIPTION

A 19-year-old man had sustained a gunshot wound to the head. Delayed digital subtraction angiography showed de novo formation of the left internal carotid artery ophthalmic segment and left MCA M2 segment pseudoaneurysms. We had initially performed coil embolization of the left MCA pseudoaneurysm. However, it had recurred 2 weeks later. We treated both pseudoaneurysms with flow diversion using the Pipeline Flex embolization device. The patient has continued with dual antiplatelet therapy of aspirin and ticagrelor. Follow-up digital subtraction angiography at 6 months showed complete obliteration of both pseudoaneurysms with patent parent vessels. The patient remained neurologically intact.

CONCLUSIONS

Flow diversion can be an efficacious treatment of traumatic MCA pseudoaneurysms in appropriately selected cases. The risks versus benefits of dual antiplatelet therapy must be weighed in trauma settings.

A Multicenter Pilot Study on the Clinical Utility of Computational Modeling for Flow-Diverter Treatment Planning

BACKGROUND AND PURPOSE

Selection of the correct flow-diverter size is critical for cerebral aneurysm treatment success, but it remains challenging due to the interplay of device size, anatomy, and deployment. Current convention does not address these challenges well. The goals of this pilot study were to determine whether computational modeling improves flow-diverter sizing over current convention and to validate simulated deployments.

MATERIALS AND METHODS

Seven experienced neurosurgeons and interventional neuroradiologists used computational modeling to prospectively plan 19 clinical interventions. In each patient case, physicians simulated 2-4 flow-diverter sizes that were under consideration based on preprocedural imaging. In addition, physicians identified a preferred device size using the current convention. A questionnaire on the impact of computational modeling on the procedure was completed immediately after treatment. Rotational angiography image data were acquired after treatment and compared with flow-diverter simulations to validate the output of the software platform.

RESULTS

According to questionnaire responses, physicians found the simulations useful for treatment planning, and they increased their confidence in device selection in 94.7% of cases. After viewing the simulations results, physicians selected a device size that was different from the original conventionally planned device size in 63.2% of cases. The average absolute difference between clinical and simulated flow-diverter lengths was 2.1 mm. In 57% of cases, average simulated flow-diverter diameters were within the measurement uncertainty of clinical flow-diverter diameters.

CONCLUSIONS

Physicians found computational modeling to be an impactful and useful tool for flow-diverter treatment planning. Validation results showed good agreement between simulated and clinical flow-diverter diameters and lengths.