Extended monitoring of coiled aneurysms completely occluded at 6-month follow-up: late recanalization rate and related risk factors

Predictors of recurrence and complications for the endovascular treatment of unruptured middle cerebral artery aneurysm: A high-volume center experience over 12 years

OBJECT

To assess the safety and efficacy of endovascular treatment (EVT) of unruptured middle cerebral artery (MCA) aneurysms in a retrospective cohort in a high-volume center. Predictors of complications and recurrence were determined.

METHODS

Retrospectively reviewed our database of prospectively collected information for all patients with unruptured MCA aneurysms that were treated by endovascular approach from March 2008 to December 2020. A multivariate analysis was conducted to identify predictors of complications and recurrence.

RESULTS

Three hundred and fifty-one patients with 370 unruptured MCA aneurysms underwent EVT were included in this study. Seventy-three aneurysms (19.7%) were treated by coiling without stent, 297 (80.3%) with stent-assisted coiling. The procedures were performed with a technical success rate of 100%. Procedure-related neurological complications occurred in 15 patients (4.1%), including 1 patient died from post-procedural stent thrombosis. Age ≥ 65 years (P = 0.039; OR = 3.400; 95% CI, 1.065-10.860) and aneurysm size ≥ 5 mm (P = 0.009; OR = 15.524; 95% CI, 1.988-121.228) were significantly associated with ischemic complications of EVT. Three hundred and six aneurysms were (87.2%) completed image follow-up (235 DSA and 71 CE-MRA). The median angiographic follow-up time were 7.0 ± 4.3 months (range from 1 to 88 months). Follow-up angiograms showed that 249 aneurysms (81.4%) were completed occluded, 29 aneurysms (9.5%) were improved, 17 aneurysms (5.6%) were stable, and 11 aneurysms (3.6%) were recanalized and 10 of them accepted retreatments. Aneurysm size ≥ 10 mm was a predictor of recanalization (P = 0.004; OR = 11.213; 95% CI, 2.127-59.098) and stent-assisted coiling can significantly reduce recanalization (P = 0.004; OR = 0.105; 95% CI, 0.023-0.479).

CONCLUSIONS

EVT is a safe and effective therapeutics for unruptured MCA aneurysms management, and provides durable aneurysm occlusion rate during follow-up. Large MCA aneurysms have higher recurrence and ischemic complications risk after EVT. Stent-assisted coiling can significantly reduce the recurrence rate without increasing the risk of complications.

Long-Term Characteristics of De Novo Bleb Formation at the Aneurysm Neck After Coil Embolization in Unruptured Cerebral Aneurysms

OBJECTIVE

De novo bleb formation at the aneurysm neck after coil embolization of unruptured intracranial aneurysms is a rarely observed type of recurrence. The aim of this study was to elucidate the clinical characteristics of recurrent aneurysms in the long-term period.

METHODS

Between January 2002 and December 2015, 290 unruptured intracranial aneurysms were treated with coil embolization at our institution. Patients who underwent retreatment due to aneurysm recurrence were divided into 2 patterns of recanalization: de novo bleb formation at the neck of a coiled sac (type DNV) and an enlarged residual cavity without de novo bleb formation (type non-DNV).

RESULTS

Twenty-seven patients with aneurysms (9.3%) underwent retreatment (type DNV, 7; type non-DNV, 20). The initial aneurysm size of type DNV aneurysms was significantly smaller than that of type non-DNV (6.1 ± 2.2 mm vs. 10.1 ± 3.6 mm; P < 0.01), and time to retreatment in type DNV was significantly longer than that in type non-DNV (9.4 ± 5.3 years vs. 2.0 ± 2.0 years; P < 0.01). Two type DNV basilar artery (BA) aneurysms ruptured after a few years; however, the other type DNV aneurysms, including 4 anterior circulation aneurysms (including the internal carotid artery), were observed to grow gradually without rupture for >10 years until retreatment.

CONCLUSIONS

De novo bleb formation at the neck of a coiled sac emerges with insidious growth during long-term follow-up. Constant caution should be exercised, even in cases of small- and medium-sized anterior circulation aneurysms. A risk of rupture risk may be anticipated, especially in BA lesions.

Usefulness of Craniograms in Discriminating Coiled Intracranial Aneurysms Requiring Retreatment

While endovascular coil embolization has become one of the major therapeutic modalities for intracranial aneurysms, long-term imaging follow-up is required because of the higher rate of retreatment compared with surgical clipping. The purpose of this study was to show the usefulness of craniograms to discriminate coiled intracranial aneurysms that required retreatment. Under the study protocol approved by institutional review board, a retrospective review of the medical record was done regarding coil embolization for intracranial aneurysms performed between January 2014 and December 2018. Coil embolization performed as the initial treatment and followed up for more than 1 year without additional treatment, and those performed as retreatment after the initial coil embolization performed at our institution were recruited. Craniograms obtained just after the initial treatment were compared with those obtained just before the additional treatment in the retreated cases and compared with the latest ones in the non-recurrence cases. Correlation between the morphological changes in the coil mass on the craniograms and retreatments was evaluated. During the study period, 288 coil embolization procedures for intracranial aneurysms were performed. From these, 191 treatments that were followed up for more than 1 year without any additional treatments and 30 retreatments were included. Morphological change of the coil mass was observed in 4 of the 191 non-recurrence treatments and 26 of the 30 retreatments, which was significantly correlated with retreatments (p <0.001). Craniogram was a useful modality in following up the coiled intracranial aneurysms to detect those required retreatments.

Risk Factors for Recanalization after Coil Embolization

The aim of our study was to identify risk factors for recanalization 6 months after coil embolization using clinical data followed by computational fluid dynamics (CFD) analysis. Methods: Firstly, clinical data of 184 patients treated with coil embolization were analyzed retrospectively. Secondly, aneurysm models for high/low recanalization risk were generated based on ROC curves and their cut-off points. Afterward, CFD was utilized to validate the results. Results: In multivariable analysis, aneurysm filling during the first embolization was an independent risk factor whilst packing density was a protective factor of recanalization after 6 months in patients with aSAH. For patients with unruptured aneurysms, packing density was found to be a protective factor whilst the aneurysm neck size was an independent risk factor. Complex flow pattern and multiple vortices were associated with aneurysm shape and were characteristic of the high recanalization risk group. Conclusions: Statistical analysis suggested that there are various factors influencing recanalization risk. Once certain values of morphometric parameters are exceeded, a complex flow with numerous vortices occurs. This phenomenon was revealed due to CFD investigations that validated our statistical research. Thus, the complex flow pattern itself can be treated as a relevant recanalization predictor.

Porous Media Computational Fluid Dynamics and the Role of the First Coil in the Embolization of Ruptured Intracranial Aneurysms

Background: The objective of our project was to identify a late recanalization predictor in ruptured intracranial aneurysms treated with coil embolization. This goal was achieved by means of a statistical analysis followed by a computational fluid dynamics (CFD) with porous media modelling approach. Porous media CFD simulated the hemodynamics within the aneurysmal dome after coiling. Methods: Firstly, a retrospective single center analysis of 66 aneurysmal subarachnoid hemorrhage patients was conducted. The authors assessed morphometric parameters, packing density, first coil volume packing density (1st VPD) and recanalization rate on digital subtraction angiograms (DSA). The effectiveness of initial endovascular treatment was visually determined using the modified Raymond–Roy classification directly after the embolization and in a 6- and 12-month follow-up DSA. In the next step, a comparison between porous media CFD analyses and our statistical results was performed. A geometry used during numerical simulations based on a patient-specific anatomy, where the aneurysm dome was modelled as a separate, porous domain. To evaluate hemodynamic changes, CFD was utilized for a control case (without any porosity) and for a wide range of porosities that resembled 1–30% of VPD. Numerical analyses were performed in Ansys CFX solver. Results: A multivariate analysis showed that 1st VPD affected the late recanalization rate (p < 0.001). Its value was significantly greater in all patients without recanalization (p < 0.001). Receiver operating characteristic curves governed by the univariate analysis showed that the model for late recanalization prediction based on 1st VPD (AUC 0.94 (95%CI: 0.86–1.00) is the most important predictor of late recanalization (p < 0.001). A cut-off point of 10.56% (sensitivity—0.722; specificity—0.979) was confirmed as optimal in a computational fluid dynamics analysis. The CFD results indicate that pressure at the aneurysm wall and residual flow volume (blood volume with mean fluid velocity > 0.01 m/s) within the aneurysmal dome tended to asymptotically decrease when VPD exceeded 10%. Conclusions: High 1st VPD decreases the late recanalization rate in ruptured intracranial aneurysms treated with coil embolization (according to our statistical results > 10.56%). We present an easy intraoperatively calculable predictor which has the potential to be used in clinical practice as a tip to improve clinical outcomes.

A Preliminary Study of the Association between SOX17 Gene Variants and Intracranial Aneurysms Using Exome Sequencing

OBJECTIVE

Conflicting results regarding SOX17 genes and the risk of intracranial aneurysms (IA) exist in the Korean population, although significant positive correlations were noted in genome-wide association studies in European and Japanese populations. Therefore, we aimed to investigate an association between SOX17 gene variants and IA using exome sequencing data.

METHODS

This study included 26 age-gender matched IA patients and 26 control subjects. The SOX17 gene variants identified from whole-exome sequencing data were examined. Genetic associations to estimate odds ratio (OR) and 95% confidence interval (CI) were performed using the software EPACTS.

RESULTS

The mean age of the IA and control groups were 51.0±9.3 years and 49.4±14.3 years, respectively (p=0.623). Seven variants of SOX17, including six single nucleotide polymorphisms and one insertion and deletion, were observed. Among these variants, rs12544958 (A>G) showed the most association with IA, but the association was not statistically significant (OR, 1.97; 95% CI, 0.81-4.74; p=0.125). Minor allele frequencies of the IA patients and controls were 0.788 and 0.653, respectively. None of the remaining variants were significantly associated with IA formation.

CONCLUSION

No significant association between SOX17 gene variants and IA were noted in the Korean population. A large-scale exome sequencing study is necessary to investigate any Korean-specific genetic susceptibility to IA.

Predictors of Cerebral Aneurysm Rupture after Coil Embolization: Single-Center Experience with Recanalized Aneurysms

BACKGROUND AND PURPOSE

Recanalization after coil embolization is widely studied. However, there are limited data on how recanalized aneurysms rupture. Herein, we describe our experience with the rupture of recanalized aneurysms and discuss the type of recanalized aneurysms at greatest rupture risk.

MATERIALS AND METHODS

A total of 426 unruptured aneurysms and 169 ruptured aneurysms underwent coil embolization in our institution between January 2009 and December 2017. Recanalization occurred in 38 (8.9%) of 426 unruptured aneurysms (unruptured group) and 37 (21.9%) of 169 ruptured aneurysms (ruptured group). The Modified Raymond-Roy classification on DSA was used to categorize the recanalization type. Follow-up DSA was scheduled until 6 months after treatment, and follow-up MRA was scheduled yearly. If recanalization was suspected on MRA, DSA was performed.

RESULTS

In the unruptured group, the median follow-up term was 74.0 months. Retreatment for recanalization was performed in 18 aneurysms. Four of 20 untreated recanalized aneurysms (0.94% of total coiled aneurysms) ruptured. In untreated recanalized aneurysms, class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .025). In the ruptured group, the median follow-up term was 28.0 months. Retreatment for recanalization was performed in 16 aneurysms. Four of 21 untreated recanalized aneurysms (2.37% of total coiled aneurysms) ruptured. Class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .02).

CONCLUSIONS

The types of recanalization after coil embolization may be predictors of rupture. Coiled aneurysms with class IIIb recanalization should undergo early retreatment because of an increased rupture risk.

Factors affecting recurrence and management of recurrent cerebral aneurysms after initial coiling

OBJECTIVE

To investigate factors affecting recurrence and effects and safety of endovascular retreatment for aneurysms recurrent after embolization.

METHODS

Among 815 aneurysms treated with embolization, recurrence was in 114 aneurysms (14.0%). Forty-three recurrent aneurysms were managed with re-embolization. Procedural complications, angiographic, and clinical results of retreatment were analyzed.

RESULTS

Patients with recurrent aneurysms were significantly (P < 0.01) younger than without recurrence (51.09 ± 10.46 vs. 53.88 ± 9.61 years). Recurrent aneurysms (n = 114) were significantly (P = 0.00) greater (11.12 ± 8.35 vs. 5.81 ± 3.44 mm) with a significantly (P = 0.00) greater neck (4.34 ± 2.26 vs. 2.90 ± 1.44 mm) than without recurrence. The rupture status of aneurysms significantly (P = 0.00) affected recurrence at follow-up. Significantly (P = 0.00) more aneurysms without recurrence were treated with advanced embolization techniques (81.0% vs. 62.3%) and got complete occlusion at the first embolization than those with recurrence (93.7% vs. 36.8%). In treating 43 recurrent aneurysms, stent-assisted recoiling was used in 48.8% in the first retreatment and 50% in the second and third retreatment procedures. Angiographic follow-up in 38 (88.4%) cases showed complete or near complete occlusion in 30 aneurysms, with the rest eight aneurysms experiencing a second recurrence (21.1%). Of the eight aneurysms with the second recurrence, five underwent the second endovascular retreatment, with complete aneurysm occlusion achieved in three cases (60%), near-complete occlusion in one (20%), and incomplete occlusion in one case at immediate angiography and six-month follow-up. Procedure-related complications occurred in three patients.

CONCLUSIONS

Endovascular retreatment of recurrent previously coiled aneurysms is safe and effective even though advanced embolization techniques are frequently involved especially for large and giant aneurysms.

Determination of Aneurysm Volume Critical for Stability After Coil Embolization: A Retrospective Study of 3530 Aneurysms

BACKGROUND

Recurrence is one of the concerns even after successful endovascular treatment of intracranial aneurysms. We sought to determine the critical aneurysm volume and risk factors related to aneurysmal stability in patients undergoing coil embolization of intracranial aneurysms.

METHODS

Aneurysm volume and follow-up imaging data were retrieved in 3042 patients with 3530 aneurysms who were treated with endovascular coil embolization from January 2006 to October 2016. We analyzed the anatomic outcome in relation to aneurysm volume and determined the critical aneurysm volume favoring coil embolization.

RESULTS

Recanalization rates were 2.8%, 6.3%, 19.4%, and 67.4% in each group with aneurysm volume of <10, 10-100, 100-1000, and >1000 mm³, respectively. When we investigated the 100-1000 mm³ group, the recanalization rate remarkably increased at 500 mm³ (16.4% vs. 57.5%, P < 0.0001; odds ratio [OR], 6.968; 95% confidence interval [CI], 3.562-13.631). In the entire cohort, recanalization rates were significantly different between aneurysm volume of <500 and >500 mm³ (7.2% vs. 62.9%, respectively; P < 0.0001; OR, 21.848; 95% CI, 13.944-34.235). In aneurysm volumes of >500 mm³, the location was a significant prognostic factor for long-term stability (posterior circulation vs. anterior circulation; OR, 4.737; 95% CI, 1.275-17.602; P = 0.020).

CONCLUSIONS

In our series of cerebral aneurysms treated with coil embolization, 500 mm³ was found to be the critical volume determining stability after coil embolization. Large volume aneurysms in the posterior circulation were especially prone to recanalization after coiling.

Is 3 years adequate for tracking completely occluded coiled aneurysms?

OBJECTIVE

The authors conducted a study to ascertain the long-term durability of coiled aneurysms completely occluded at 36 months' follow-up given the potential for delayed recanalization.

METHODS

In this retrospective review, the authors examined 299 patients with 339 aneurysms, all shown to be completely occluded at 36 months on follow-up images obtained between 2011 and 2013. Medical records and radiological data acquired during the extended monitoring period (mean 74.3 ± 22.5 months) were retrieved, and the authors analyzed the incidence of (including mean annual risk) and risk factors for delayed recanalization.

RESULTS

A total of 5 coiled aneurysms (1.5%) occluded completely at 36 months showed recanalization (0.46% per aneurysm-year) during the long-term surveillance period (1081.9 aneurysm-years), 2 surfacing within 60 months and 3 developing thereafter. Four showed minor recanalization, with only one instance of major recanalization. The latter involved the posterior communicating artery as an apparent de novo lesion, arising at the neck of a firmly coiled sac, and was unrelated to coil compaction or growth. Additional embolization was undertaken. In a multivariate analysis, a second embolization for a recurrent aneurysm (HR = 22.088, p = 0.003) independently correlated with delayed recanalization.

CONCLUSIONS

Almost all coiled aneurysms (98.5%) showing complete occlusion at 36 months postembolization proved to be stable during extended observation. However, recurrent aneurysms were predisposed to delayed recanalization. Given the low probability yet seriousness of delayed recanalization and the possibility of de novo aneurysm formation, careful monitoring may be still considered in this setting but at less frequent intervals beyond 36 months.

Endovascular coiling of proximal middle cerebral artery aneurysms: is it safe and durable?

BACKGROUND

Proximal middle cerebral artery (M1 segment) aneurysms are relatively deeply located in neighboring lenticulostriate arteries, which make them unsuitable for microsurgery. We aimed to investigate the clinical and radiological outcomes of endovascular coiling of M1 segment aneurysms.

METHODS

Between January 2003 and December 2014, we retrospectively reviewed the medical records of 52 patients (52 aneurysms) from four institutions who underwent endovascular coiling of M1 segment aneurysms. Patients who underwent clinical and radiologic follow-up for more than a year after the procedure were evaluated.

RESULTS

The aneurysms were located in the early frontal branch, early temporal branch, and lenticulostriate artery in 28, 15, and nine patients, respectively. Endovascular coiling was achieved in 51 cases and failed in one case. Of these 51 cases, 46 (90.2%) and five (9.8%) were non-ruptured and ruptured aneurysms, respectively. Initial angiographic results revealed complete occlusion in 26 (51.0%), residual neck in 16 (31.4%), and residual sac in nine (17.6%) cases. One failed case had a symptomatic procedural complication of thromboembolism. However, there was no permanent morbidity or mortality. Two major recanalization cases (3.9%) were retreated by endovascular coiling. On multivariable logistic regression analysis, aneurysmal recurrence was significantly related to aneurysm height (OR, 1.887; 95% CI, 1.107 to 3.217; p = 0.020), width (OR, 1.836; CI, 1.127 to 2.992; p = 0.015), and neck (OR, 4.017; CI, 1.220 to 13.232, p = 0.022).

CONCLUSION

Endovascular coiling of M1 segment aneurysms appeared to be a feasible treatment option with a relatively low-retreatment rate. Aneurysm size was statistically significantly associated with recurrence.

Follow-Up Outcomes After Re-Embolization for Recanalized Aneurysms After Initial Coiling: Further Recurrence Rates and Related Risk Factors

BACKGROUND

Although it is well known that coiled aneurysms can recanalize over time, long-term outcomes of re-embolization for recurred aneurysms have not been adequately investigated. We studied the retreatment outcomes of re-embolized aneurysms during follow-up monitoring and assessed the risk factors related to further recanalization.

METHODS

A total of 129 patients with 133 aneurysms were retrospectively reviewed. Each aneurysm was subjected to re-embolization because of major recanalization after initial coil embolization and underwent midterm and extended monitoring after retreatment. Cumulative medical records and radiologic data were assessed. Repeat recurrence rates and related risk factors were assessed by binary logistic regression analysis.

RESULTS

A total of 47 aneurysms (35.3%) showed re-recanalization at 6 months after re-embolization, with 17 and 30 instances of minor and major recanalization, respectively. Multivariate analysis indicated that posterior circulation (hazard ratio [HR], 6.129; P = 0.010), large aneurysm (>7 mm) (HR, 13.598; P < 0.001), and incomplete occlusion at the second coiling (HR, 9.975; P = 0.001) were significant factors for repeat recanalization. Of 86 aneurysms showing complete occlusion at the midterm, 76 were further evaluated (≥12 months), showing 18 aneurysms (23.7%) of delayed re-recanalization during a follow-up of 230.1 aneurysm-years. Of 15 aneurysms with minor recanalization at 6 months, 6 (40.0%) progressed to major recanalization during a follow-up of 44.0 aneurysm-years.

CONCLUSIONS

Most re-coiled aneurysms (64.7%) showed complete occlusion at the 6-month follow-up. However, posterior circulation, large aneurysm (>7 mm), and incomplete occlusion at the second coiling were risks for further recanalization. The midterm and delayed re-recanalization rates of the re-embolized aneurysms seem to be higher than those of the initial aneurysms.

Hemodynamics and coil distribution with changing coil stiffness and length in intracranial aneurysms

Purpose

The purpose of this study was to investigate hemodynamics and coil distribution with changing coil stiffness and length using the finite element method (FEM) and computational fluid dynamics (CFD) analysis.

Methods

Basic side-wall and bifurcation type aneurysm models were used. Six types of coil models were generated by changing the coil stiffness and length, based on commercially available embolic coils. Coil embolization was simulated using FEM. CFD was performed to characterize the hemodynamics in the aneurysms after embolization. Coil distribution and velocity reduction in the aneurysms were evaluated.

Results

The median value of radial coil distribution was shifted from the center to the outer side of the aneurysmal dome by changing coil stiffness: harder coils entered the outer side of the aneurysmal dome more easily. Short coils were more distributed at the neck region, since their small size made it easy for them to enter the tighter area. CFD results also indicated that velocity in the aneurysm was effectively reduced when the coils were more distributed at the neck region and the outer side of the aneurysmal dome because of the disturbance in blood inflow.

Conclusions

It is easier for coils to enter the outer side of the aneurysmal sphere when they are harder. If coils are short, they can enter tighter areas more easily. In addition, high coil density at the outer side of the aneurysmal dome and at the neck region is important to achieve effective velocity reduction.

Genetic Risk Assessment of Elastin Gene Polymorphisms with Intracranial Aneurysm in Koreans

Elastin encoded by elastin gene (ELN) is a crucial extracellular matrix protein responsible for arterial resilience. The objective of this study was to identify single nucleotide polymorphisms (SNPs) of ELN gene susceptible to intracranial aneurysm (IA) in Korean population. Two SNPs of ELN gene, rs2071307 (Gly422Ser) and rs2856728 (intron), were genotyped in 90 patients with IA and 90 age and frequency matched controls. Fisher’s exact test was conducted to evaluate allelic association with IA. Of the two SNPs in ELN gene, T allele of rs2856728 (intron) showed statistically significant association with increased development of IA (odds ratio [OR]: 2.34, 95% confidence interval [CI]: 1.44–3.81, P = 7.6 × 10⁻⁴). However, G allele of rs2071307 (Gly422Ser) had no significant association with the development of IA (OR: 1.27, 95% CI: 1.44–3.81, P = 0.607). Interestingly, the odds of having rs2856728 variant was approximately 2-fold higher in males than that in females (OR: 3.46 vs. 1.88, P < 0.05). However, none of SNPs showed difference between single and multiple IA in this study. This preliminary study implies that the rs2856728 variant in ELN gene polymorphisms might play crucial roles in the development and pathogenesis of IA in Korean population.

A Novel Association between Lysyl Oxidase Gene Polymorphism and Intracranial Aneurysm in Koreans

PURPOSE

Lysyl oxidase (LOX) controls the cross-linking and maturation of elastin and collagen fibers. In this study, we investigated the association between LOX gene polymorphisms and intracranial aneurysm (IA) formation in a homogeneous Korean population.

MATERIALS AND METHODS

This cross-sectional study involved 80 age-sex matched patients with IA and controls. Fisher's exact test was performed to analyze allelic associations between ten single nucleotide polymorphisms (SNPs) and IA, including 41 ruptured and 39 unruptured cases. Haplotype-specific associations were analyzed using the omnibus test estimating asymptotic chi-square statistics.

RESULTS

Of ten SNPs, three SNPs (rs2303656, rs3900446, and rs763497) were significantly associated with IA (p<0.01). The C allele of rs3900446 was significantly related to increased IA risk with a significant threshold [odds ratio (OR)=20.15, p=4.8×10⁻⁵]. Meanwhile, the A allele of rs2303656 showed a preventive effect against IA formation (p=8.2×10⁻⁴). Seventeen of 247 haplotype structures showed a suggestive association with IA (asymptotic p<0.001). Of ten SNP haplotype combinations, the CG combination of rs3900446 and rs763497 reached Bonferroni-adjusted significant threshold in IA patients (minor haplotype frequency=0.113, asymptotic p=1.3×10⁻⁵). However, there was no association between aneurysm rupture and the LOX gene.

CONCLUSION

This preliminary study indicated that LOX gene polymorphisms, such as rs2303656, rs3900446, and rs763497, may play crucial roles in IA formation in the Korean population. Our novel findings need to be validated in a large-scale independent population.

Progressive Occlusion of Small Saccular Aneurysms Incompletely Occluded After Stent-Assisted Coil Embolization : Analysis of Related Factors and Long-Term Outcomes

PURPOSE

Incompletely occluded aneurysms after coil embolization are subject to recanalization but occasionally progress to a totally occluded state. Deployed stents may actually promote thrombosis of coiled aneurysms. We evaluated outcomes of small aneurysms (<10 mm) wherein saccular filling with contrast medium was evident after stent-assisted coiling, assessing factors implicated in subsequent progressive occlusion.

METHODS

Between September 2012 and June 2016, a total of 463 intracranial aneurysms were treated by stent-assisted coil embolization. Of these, 132 small saccular aneurysms displayed saccular filling with contrast medium in the immediate aftermath of coiling. Progressive thrombosis was defined as complete aneurysmal occlusion at the 6‑month follow-up point. Rates of progressive occlusion and factors predisposing to this were analyzed via binary logistic regression.

RESULTS

In 101 (76.5%) of the 132 intracranial aneurysms, complete occlusion was observed in follow-up imaging studies at 6 months. Binary logistic regression analysis indicated that progressive occlusion was linked to smaller neck diameter (odds ratio [OR] = 1.533; p = 0.003), hyperlipidemia (OR = 3.329; p = 0.036) and stent type (p = 0.031). The LVIS stent is especially susceptible to progressive thrombosis, more so than Neuroform (OR = 0.098; p = 0.008) or Enterprise (OR = 0.317; p = 0.098) stents. In 57 instances of progressive thrombosis, followed for ≥12 months (mean 25.0 ± 10.7 months), 56 (98.2%) were stable, with minor recanalization noted once (1.8%) and no major recanalization.

CONCLUSION

Aneurysms associated with smaller diameter necks, hyperlipidemic states and LVIS stent deployment may be inclined to possible thrombosis, if occlusion immediately after stent-assisted coil embolization is incomplete. In such instances, excellent long-term durability is anticipated.

Risk Factor Analysis of Recanalization Timing in Coiled Aneurysms: Early versus Late Recanalization

BACKGROUND AND PURPOSE

Long-term documentation of anatomic and angiographic characteristics pertaining to the timing of recanalization in coiled aneurysms has been insufficient. Our intent was to analyze and compare early and late-phase recanalization after coiling, identifying respective risk factors.

MATERIALS AND METHODS

A total of 870 coiled saccular aneurysms were monitored for extended periods (mean, 30.8 ± 8.3 months). Medical records and radiologic data were also reviewed, stratifying patients as either early (n = 128) or late (n = 52) recanalization or as complete occlusion (n = 690). Early recanalization was equated with confirmed recanalization within 6 months after the procedure, whereas late recanalization was defined as verifiable recanalization after imaging confirmation of complete occlusion at 6 months. A multinomial regression model served to assess potential risk factors, the reference point being early recanalization.

RESULTS

Posterior circulation (P = .009), subarachnoid hemorrhage at presentation (P = .011), second attempt for recanalized aneurysm (P < .001), and aneurysm size >7 mm (P < .001) emerged as variables significantly linked with early recanalization (versus complete occlusion). Late (versus early) recanalization corresponded with aneurysms ≤7 mm (P = .013), and in a separate subanalysis of lesions ≤7 mm, aneurysms 4-7 mm showed a significant predilection for late recanalization (P = .008). However, the propensity for complete occlusion in smaller lesions (≤7 mm) increased as the size diminished.

CONCLUSIONS

Although long-term complete occlusion after coiling was more likely in aneurysms ≤7 mm, such lesions were more prone to late (versus early) recanalization, particularly those of 4-7 mm in size. Long-term follow-up imaging is thus appropriate in aneurysms >4 mm to detect late recanalization of those formerly demonstrating complete occlusion.

Predisposing factors for recanalization of cerebral aneurysms after endovascular embolization: a multivariate study

BACKGROUND

The recanalization of cerebral aneurysms after endovascular embolization (coiling or stent-assisted coiling) has been a matter of concern.

OBJECTIVE

To systematically evaluate the predisposing factors for cerebral aneurysm recanalization using multidimensional analysis in a large patient cohort.

METHODS

In 238 patients with 283 aneurysms, patient baseline characteristics, aneurysm morphological characteristics, treatment-related factors, and changes in flow hemodynamics after endovascular treatment (coiling or stent-assisted coiling) were compared between the recanalization and non-recanalization groups. Multivariate logistic regression analysis was performed to determine independent risk factors correlated with recanalization.

RESULTS

16 aneurysms treated by coiling recanalized, with a recurrence rate of 18.6%, and 24 recanalized in the lesions treated by stent-assisted coiling, with a recanalization rate of 12.2%. Large aneurysms (>10 mm, p=0.002) and a follow-up interval >1 year (p=0.027) were shown to be statistically significant between the recanalization and non-recanalization groups. For flow hemodynamic changes, three parameters (velocity on the neck plane, wall shear stress on the neck wall, and wall shear stress on the whole aneurysm) showed a relatively lower amplitude of decrease after endovascular treatment in the recanalization group. Interestingly, the velocity on the neck plane and wall shear stress on the neck wall may be elevated after treatment. Specifically, the reduction ratio (RR) of velocity on the neck plane showed significant difference between the groups in the multivariate analysis (p=0.013), and was considered an independent risk factor for recanalization.

CONCLUSIONS

The aneurysm size, follow-up interval, and flow hemodynamic changes, especially the RR of velocity on the neck plane, have important roles in aneurysm recanalization.

Analysis of Multiple Intracranial Aneurysms with Different Outcomes in the Same Patient After Endovascular Treatment

BACKGROUND

Aneurysm recanalization after coiling, with or without stent assistance, is a major issue in the endovascular management of intracranial aneurysms. Multiple intracranial aneurysms with different outcomes after endovascular treatment may represent a useful disease model in which patient-specific risk factors can be balanced to investigate possible features linked to aneurysm recanalization. In the present study, we evaluated the impact of aneurysm-specific, treatment-related, and hemodynamics-related factors on multiple aneurysms and to explore the reason why one aneurysm recanalized and the other did not.

METHODS

Between 2010 and 2015, 763 multiple intracranial aneurysms in 326 patients were diagnosed by digital subtraction angiography. We retrospectively collected and analyzed 13 pairs of multiple aneurysms with different outcomes (recanalized or stable) in the same patient. Patient-specific models were constructed and analyzed by a computational fluid dynamics method. The virtual stent deployment method was used, and the coils were simulated by a porous medium model. Factors were evaluated for significance with respect to recanalization.

RESULTS

Aneurysm size (P = 0.021), neck width (P = 0.027), ruptured aneurysms (P = 0.002), reduction ratio of averaged velocity (P = 0.008), and wall shear stress (P = 0.024) were significantly associated with aneurysm recanalization. By contrast, the aneurysm location, all of treatment-related factors (packing density, duration of follow-up, stent use, initial angiographic result) and the reduction ratio of averaged pressure were not significantly associated (P > 0.05).

CONCLUSIONS

Small aneurysm size and neck width, unruptured aneurysm, and perianeurysmal hemodynamics with marked reduction may be important factors associated with the midterm durability of aneurysm embolization.