Progressive thrombosis of small saccular aneurysms filled with contrast immediately after coil embolization: analysis of related factors and long-term follow-up

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.

Does Systemic Hypertension Impact Recanalization of Coiled Aneurysms?

PURPOSE

It is well known that hypertension is a significant factor in the formation, growth, and rupture of aneurysms and recanalization of coiled aneurysms is affected by hemodynamic stress. At present, however, the impact of hypertension on recanalization of coiled aneurysms has not been adequately investigated. This study examined the relation between hypertension and subsequent outcomes of coiled aneurysms, using a matched patient analysis.

METHODS

A total of 715 subjects undergoing coil embolization of intracranial aneurysms between 2011 and 2013 were selected for study. Time-of-flight magnetic resonance or conventional angiography was used (singly or together) to gauge degrees of occlusion after coiling, applying the Raymond classification in grading recanalization. Patients with hypertension were grouped as controlled or uncontrolled, based on blood pressure readings at outpatient clinics. Hypertensive and non-hypertensive subjects were matched (1:1) for several relevant variables.

RESULTS

Overall, 484 patients (67.7%) were hypertensive (controlled 338; uncontrolled 146). During the follow-up period (28.6 ± 9.7 months), 129 aneurysms (18.0%) displayed recanalization (minor 58; major 71). Patient age, concomitant diabetes, hyperlipidemia, aneurysm size, neck size, depth-to-neck ratio, and aneurysm type differed significantly in hypertensive and non-hypertensive groups; however, group incidences of cumulative recanalization were similar (p = 0.297). After 1:1 matching the cumulative recanalization rate (13.5%) in hypertensive and non-hypertensive counterparts (14.3%) again proved similar (p = 0.578). In the hypertensive group, in addition, recanalization showed no relation to controlled and uncontrolled subgroup (odds ratio, OR = 1.000, p > 0.999).

CONCLUSION

Unlike other aspects of evolving aneurysms (e.g. formation, growth, or rupture), recanalization of coiled aneurysms seems to be unaffected by systemic hypertension.

Progressive thrombosis of unruptured aneurysms after coil embolization: analysis of 255 consecutive aneurysms

Introduction

We have observed that aneurysms treated by insufficient coil embolization and filled with contrast agent immediately after the procedure are often completely occluded at follow-up. However, there are limited studies showing progressive thrombosis of aneurysms after coil embolization. Herein, we describe our experience with coil embolization for aneurysms, and discuss the factors involved in progressive thrombosis.

Methods

A total of 255 aneurysms treated by coil embolization in our institute between January 2011 and June 2017 and observed >6 months were included. ‘Progressive thrombosis’ indicated that aneurysms that were neck remnant (NR) or dome filling (DF) immediately after coil embolization changed to complete obliteration (CO) at the 6-month follow-up digital subtraction angiography. The factors involved in progressive thrombosis were assessed.

Results

In all aneurysms (n=255), 24 (9.4%) were CO, 82 (32.2%) were NR, and 149 (58.4%) were DF immediately after the procedure. At 6-month digital subtraction angiography, 123 (48.2%) were CO, 95 (37.3%) were NR, and 37 (14.5%) were DF. Retreatment for major recanalization was performed in eight cases (3.1%). One hundred and three aneurysms showed progressive thrombosis. There were significant differences in aneurysm location (P=0.0002), aneurysm dome diameter (P=0.0015), aneurysm neck diameter (P=0.0068), volume embolization ratio (P=0.0054), and endovascular procedure with stent (P=0.0264) between the progressive thrombosis and no thrombosis groups.

Conclusions

Progressive thrombosis can occur in aneurysms after coil embolization depending on aneurysm location and size, and stent use. Thus, the degree of coil embolization and combination with a stent should be adjusted depending on aneurysm type.

Effect of Straightening the Parent Vessels in Stent-Assisted Coil Embolization for Anterior Communicating Artery Aneurysms

BACKGROUND

Stent-assisted coil embolization (SAC) for treating anterior communicating artery (AcomA) aneurysms is safe and effective. Straightening of parent vessels by stent placement can lead to progressive thrombosis. We describe our experience with SAC for AcomA aneurysms and demonstrate the effect of straightening the parent vessels.

METHODS

A total of 26 patients with AcomA aneurysms were treated using SAC in our institute between July 2010 and December 2017. Follow-up digital subtraction angiography was performed 6 months after treatment, magnetic resonance angiography was performed every year, and outcomes were analyzed.

RESULTS

From all aneurysms (n = 24), 12 (50.0%) were neck remnant, and 12 (50.0%) were dome-filling types immediately after the procedure. At the 6-month digital subtraction angiography follow-up (n = 22), 13 (59.1%) aneurysms were complete obliteration, 8 (36.4%) were neck remnant, and 1 (4.5%) was dome filling. The median parent vessel angle was measured preoperatively at 98.1°, increased to 124.8° immediately after stent deployment, and further increased to 149.6° at the 6-month follow-up. Progressive thrombosis was observed in 13 of 22 (59.1%) aneurysms. The parent vessel angle change immediately after stent deployment in the progressive thrombosis group tended to be larger than that observed in the no thrombosis group; this change was significant at the 6-month follow-up. The median follow-up term was 18 months. No patients required retreatment.

CONCLUSIONS

Good SAC outcomes were achieved for AcomA aneurysms, and hemodynamic changes related to straightening of the parent vessels is a consideration in SAC.

Stent-assisted coil embolization of anterior communicating artery aneurysms: safety, effectiveness, and risk factors for procedural complications or recanalization

INTRODUCTION

Stent-assisted coil (SAC) embolization is an alternative treatment option for anterior communicating artery (AcoA) aneurysms. This study was undertaken to assess the safety and effectiveness of SAC embolization in treating AcoA aneurysms and to determine risk factors for related procedural complications or recanalization.

METHODS

Between August 2008 and December 2016, 184 patients with AcoA aneurysms were treated with SAC embolization. Cumulative medical record and radiologic data were analyzed using binary logistic regression to identify factors predisposing to procedural complications or recanalization.

RESULTS

Contralateral A1 segment hypoplasia was observed in 59 patients (32.1%). Three types of stents (LVIS, Enterprise, and Neuroform) were variably placed by one of two routes: (1) ipsilateral A1 to ipsilateral A2 (75.5%) or (2) ipsilateral A1 to contralateral A2 (24.5%). Procedural complications occurred in 17 patients (thromboembolism 12; procedural leakage 3; both 2), showing a significant relation to subarachnoid hemorrhage at presentation (OR 57.750; P<0.01). Occlusion was documented immediately after embolization in 130 aneurysms (70.6%) and, in 23 (13.1%) of 175 AcoA aneurysms followed by angiography (median 25.9±18.5 months), recanalization developed (minor, 15; major, 8). Stent configuration (ipsilateral A1 to contralateral A2, P=0.024), maximum aneurysm size (>7 mm, P<0.01), and A1 segment hypoplasia (P=0.039) were identified as risk factors for recanalization.

CONCLUSION

SAC embolization is a safe and effective method of treating unruptured AcoA aneurysms, regardless of anatomic or clinical features. However, in the event of rupture, procedural complications are likely. Stent configuration, aneurysm size, and A1 segment hypoplasia were identified as significant risk factors for recanalization.

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.

Growth-Related Major Recanalization of Coiled Aneurysms: Incidence and Risk Factors

BACKGROUND

Though endovascular techniques and procedural devices continue to advance, recurrence of embolized aneurysms is still problematic. Enlarging size during follow-up is the presumed basis of recanalization in some lesions, but such growth has not been adequately investigated.

OBJECTIVE

To generate estimates of growth in coiled aneurysms with major recanalization, focusing on incidence and risk factors involved.

METHODS

A cohort of 134 patients harboring 139 aneurysms were retrospectively reviewed, each subjected to re-embolization for major recanalization after initial coil embolization. Cumulative medical records and radiological data were assessed. The aneurysms were grouped by nature of recanalization, either related or unrelated to growth. Growth was defined as &gt;50% increase in aneurysm volume (including coil mass) at the time of re-embolization, compared initial status. Aneurysm volumes were determined by volume of coil mass within full confines of the aneurysm. Univariate and multivariate analyses were performed to identify risk factors predisposing to growth.

RESULTS

Major recanalization was growth related in 74 coiled aneurysms (53.2%) and unrelated to growth (by coil compaction) in 65 (46.8%). Multiple logistic regression analysis indicated that growth of coiled aneurysm was linked to aneurysms initially ruptured at presentation (P = .002) and aneurysm size &lt;7 mm (P &lt; .001). Cumulative growth rates were as follows: 14 (18.9%), 6 mo; 18 (24.3%), 12 mo; 13 (17.6%), 24 mo; 10 (13.5%), 36 mo; and 19 (25.7%), &gt;36 mo.

CONCLUSION

Our data suggest that aneurysms presenting with hemorrhage and small-sized aneurysms (&lt;7 mm) are predisposed major recanalization by growth after coil embolization, as opposed to coil compaction.

Stand-alone coil embolization of anterior communicating artery aneurysms: Efficacy and technical issues

OBJECTIVE

We report our experience with endovascular coiling of anterior communicating artery aneurysms with special consideration of angiographic and clinical outcomes and periprocedural complications.

MATERIALS AND METHODS

The analysis included treatment results of 28 patients with ruptured and unruptured aneurysms. The aneurysm size ranged from 1.8 to 9.8 mm (mean 5.2, SD 1.7). Clinical examinations with the use of modified Rankin Score and angiographic outcomes were evaluated initially post-embolization and at a minimum follow-up of six months.

RESULTS

Initial post-treatment complete and near-complete aneurysm occlusion was achieved in 27 (96%) cases and incomplete occlusion in one (4%) case. Imaging follow-up, performed in 15 (53.6%) patients, showed no change in the degree of occlusion in 11 (73%), coil compaction in one (7%) and progressive occlusion in three (20%) patients. Three (20%) patients underwent a second coil embolization. The procedure-related severe morbidity and mortality rate was 6.4% (2/31). Coil prolapse was present in one (3.2%) case and intraprocedural aneurysm rupture in three (9.6%) cases. The clinical follow-up evaluation achieved in 19 (67.9%) patients showed no change in 17 (89.5%) patients and improvement in two (10.5%) patients.

CONCLUSIONS

Although the efficacy of coil embolization of anterior communicating artery aneurysms is unquestionable and the procedure-related complications are acceptable, they should not be neglected. Further investigations are needed to better understand protective factors, as well as to establish unequivocally appropriate management strategy of these complications.

Stent deployment protocol for optimized real-time visualization during endovascular neurosurgery

Successful application of endovascular neurosurgery depends on high-quality imaging to define the pathology and the devices as they are being deployed. This is especially challenging in the treatment of complex cases, particularly in proximity to the skull base or in patients who have undergone prior endovascular treatment. The authors sought to optimize real-time image guidance using a simple algorithm that can be applied to any existing fluoroscopy system. Exposure management (exposure level, pulse management) and image post-processing parameters (edge enhancement) were modified from traditional fluoroscopy to improve visualization of device position and material density during deployment. Examples include the deployment of coils in small aneurysms, coils in giant aneurysms, the Pipeline embolization device (PED), the Woven EndoBridge (WEB) device, and carotid artery stents. The authors report on the development of the protocol and their experience using representative cases. The stent deployment protocol is an image capture and post-processing algorithm that can be applied to existing fluoroscopy systems to improve real-time visualization of device deployment without hardware modifications. Improved image guidance facilitates aneurysm coil packing and proper positioning and deployment of carotid artery stents, flow diverters, and the WEB device, especially in the context of complex anatomy and an obscured field of view.

Fate of Coiled Aneurysms with Minor Recanalization at 6 Months: Rate of Progression to Further Recanalization and Related Risk Factors

BACKGROUND AND PURPOSE

Minor recanalization in coiled aneurysms may remain stable with time or may progress to major recanalization. Our aim was to monitor the aneurysms displaying minor recanalization in imaging studies at 6 months, gauging major recanalization rates and related risk factors through extended follow-up.

MATERIALS AND METHODS

Sixty-five aneurysms (in 65 patients) showing minor recanalization in follow-up imaging at 6 months were reviewed retrospectively. Medical records and radiologic data accruing during extended monitoring (mean, 24.8 ± 8.2 months) were assessed. Univariate and multivariate analyses were conducted to identify risk factors for progression from minor-to-major recanalization.

RESULTS

Progression to major recanalization was observed in 24 (36.9%) of the initially qualifying aneurysms during a follow-up of 112.5 aneurysm-years, for an annual rate of 17.84% per aneurysm-year. Progression was determined chronologically as follows: 14 (58.3%) at 6 months, 8 (33.3%) at 18 months, and 2 (8.4%) at 30 months. Stent deployment significantly decreased the occurrence of major recanalization (OR = 0.22, P = .03), whereas antiplatelet therapy (OR = 0.82, P = .75), posterior location (OR = 0.24, P = .20), and second coiling for recanalized aneurysms (OR = 0.96, P = .96) were unrelated.

CONCLUSIONS

Our analysis determined a 36.9% rate of major recanalization during a follow-up of 112.5 aneurysm-years in coiled aneurysms showing minor recanalization at 6 months. Stent deployment alone conferred a protective effect, preventing further recanalization without additional treatment. Given the fair probability of late major recanalization, aneurysms showing minor recanalization at 6 months should be monitored diligently, particularly in the absence of stent placement.

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

OBJECTIVES

To estimate long-term durability in coiled aneurysms completely occluded at 6-month follow-up imaging, focusing on late recanalization rate and the risk factors involved.

METHODS

A cohort of 620 patients harbouring 698 completely occluded coiled aneurysms at 6-month follow-up was subjected to extended monitoring (mean, 24.5 ± 7.9 months). Cumulative recanalization rate and related risk factors were analysed using Cox proportional hazards regression and Kaplan-Meier product-limit estimator.

RESULTS

Forty-three aneurysms (6.2 %) occluded completely at 6-months displayed recanalization (3.02 % per aneurysm-year) during continued surveillance (1425.5 aneurysm-years), with 26 (60.5 %) surfacing in another 6 months, 15 (34.9 %) within 18 months and 2 (4.6 %) within 30 months. Cumulative survival rates without recanalization were significantly lower in subjects with aneurysms >7 mm (p = 0.014), with bifurcation aneurysms (p = 0.009) and with subarachnoid haemorrhage (SAH) at presentation (p < 0.001). Multivariate analysis indicated that aneurysms >7 mm (HR = 2.37, p = 0.02) and bifurcation aneurysms (HR = 2.70, p = 0.03) were significant factors in late recanalization, whereas a link with SAH at presentation was marginal (HR = 1.92, p = 0.06) and stent placement fell short of statistical significance (HR = 0.47; p = 0.12).

CONCLUSION

Most (93.8 %) coiled aneurysms showing complete occlusion at 6 months post-procedure were stable in long-term monitoring. However, aneurysms >7 mm and bifurcation aneurysms were predisposed to late recanalization.

KEY POINTS

• Most coiled aneurysms showing complete occlusion at 6 months were stable. • Forty-three aneurysms (6.2 %) occluded completely at 6-month follow-up displayed late recanalization. • Late recanalization rate was 3.02 % per aneurysm-year during follow-up of 1425.5 aneurysm-years. • Aneurysms over 7 mm and bifurcation aneurysms were predisposed to late recanalization.

Effect of stenting on progressive occlusion of small unruptured saccular intracranial aneurysms with residual sac immediately after coil embolization: a propensity score analysis

Background

To examine the effect of stenting on progressive occlusion of small and incompletely occluded unruptured intracranial aneurysms (UIAs) ≤10 mm in size using a propensity score matched case controlled analysis.

Methods

715 small UIAs consecutively treated by coiling between 2008 and 2010 were eligible for study. Time of flight MR angiography and/or catheter angiography were used to estimate extent of occlusion after coiling. Complete occlusion at 6 months post embolization of a sac filled with contrast immediately after coiling constituted progressive occlusion. A propensity score matched analysis was conducted, based on the probability of stent deployment.

Results

206 (28.8%) small UIAs showed residual sac filling directly after coiling. Of these, 182 (88.3%) displayed progressive occlusion at 6 months. Aneurysm size (p<0.01), neck size (p<0.01), and embolization attempt (p<0.01) differed significantly for stented and non-stented lesions, but the incidence of progressive occlusion did not differ (p=0.78) between the groups. After 1:1 propensity score matching, however, the rate of complete occlusion in stented subjects (97.5%) surpassed that of the non-stented counterparts (OR=9.75, p=0.01).

Conclusions

Small UIAs with residual sac filling after coiling showed a complete occlusion rate of 88.3% at 6 months post embolization. Stent deployment seems to promote complete occlusion in such lesions.