Anatomical results, rebleeding and factors that affect the degree of occlusion in ruptured cerebral aneurysms after endovascular therapy

Intermediate catheter use is associated with complete occlusion and dense packing in coil embolization of unruptured cerebral aneurysms: a propensity score matched study

BACKGROUND

An intermediate catheter (IMC) can improve the maneuverability and stability of the microcatheter.

OBJECTIVE

To investigate the efficacy and safety of using an IMC in triaxial systems for coil embolization of unruptured cerebral aneurysms (UCAs).

METHODS

A total of 2430 consecutive saccular UCAs (2259 patients) that underwent initial coil embolization at three institutions between November 2003 and May 2023 were retrospectively reviewed. Patients were classified into two groups: with IMC (IMC(+)) and without IMC (IMC(-)). To investigate whether IMC use increased the rate of complete occlusion and the packing density, a propensity score-matched analysis was used to control for clinical, anatomical, and procedural features.

RESULTS

Ultimately, 595 (24.5%) coil embolization used an IMC. Propensity score matching was successful for 424 paired IMC(+) and IMC(-) aneurysms. Compared with the IMC(-) group, the IMC(+) group had significantly higher rate of Raymond-Roy Occlusion Classification class 1 immediately after treatment (30.0% vs 20.8%, P=0.003) and at 6 months (28.8% vs 20.0%, P=0.004) and a higher volume embolization ratio (27.2% (SD 6.5%) vs 25.9% (SD 6.2%), P=0.003). Re-treatment rates were not significantly different between the two groups (0.7% vs 0.2%, P=0.624). No significant differences in the incidences of ischemic and hemorrhagic complications and IMC-related parent artery dissection were found between the two groups.

CONCLUSION

Use of IMCs in triaxial systems can provide effective and safe support in coil embolization of UCAs because complete occlusion and dense coil packing can be achieved without increased complications.

Changes in Modified Raymond-Roy Classification Occlusion Classes and Predictors of Recurrence-Free Survival in Patients with Intracranial Aneurysms after Endovascular Coil Embolization

PURPOSE

To assess changes in modified Raymond-Roy classification (MRRC) occlusion classes and recurrence rates over time and evaluate recurrence-free survival after coil embolization and its predictors.

MATERIALS AND METHODS

During 2007-2016, 201 patients (mean age, 57.1 ± 13.4 years; 75.5% women) with 240 aneurysms treated with coil embolization were enrolled. MRRC Class I (n = 210), Class II (n = 14), Class IIIa (n = 10), and Class IIIb (n =6) closures were assessed. Recurrence was defined as recanalization in MRRC Class I closures or an increase of at least 20% in any of the dimensions of the remnants of the other classes. Recurrence-free survival and its predictors were analyzed using survival analysis.

RESULTS

Most changes in MRRC class occurred in the first year after treatment. MRRC Class I closures had a slightly lower probability of change than that associated with other classes within 1-5 years, whereas Class IIIb closures remained unchanged. Rates of recurrence or regression for all classes were highest within the first year. The median recurrence-free survival times among patients with Class IIIa and Class IIIb closures were 11.56 and 5.55 months, respectively. Significant predictors of recurrence included aneurysm size of 13-24 mm, ruptured or wide-necked aneurysms, and MRRC Class IIIa or IIIb closures.

CONCLUSIONS

Class changes and recurrence rates for all MRRC classes were highest in the first year. MRRC Class IIIb closures had the highest recurrence rate and the shortest recurrence-free survival. Recurrence risk increased in Classes IIIa and IIIb and with large, ruptured or wide-necked aneurysms.

EFFECTS OF THE ANEURYSM TREATMENT METHOD ON COIL PACKING DENSITY AND ITS RELATIONSHIP WITH THE OSTIUM AREA

PURPOSE

To test the following hypotheses: (1) balloon or stent assistance increases coil packing density (CPD) in the endovascular treatment of intracranial aneurysms and (2) CPD is related to the ostium area and volume of the aneurysm.

MATERIALS AND METHODS

This retrospective study included 60 ruptured and unruptured (54 and 6, respectively) aneurysms treated between August 2017 and December 2019 in the authors' institution with simple coiling (n=18), balloon-assisted coiling (n=7), or stent-assisted coiling (n=35). Aneurysm volume and ostium area measurements were obtained using commercial software from three-dimensional digital subtraction angiography images. Coil sizes were retrieved from patient files, and coil volume measurements were obtained using https://www.angiocalc.com/. Analysis of covariance, multivariable covariance analysis, and Pearson's correlation analyses were performed.

RESULTS

The median values for the aneurysm volume, coil volume, CPD, and ostium area were 63.4 (range 5.5-1771.4) mm³, 23.13 (2.03-296.95) mm³, 33.29% (13.41%-81.02%), and 10.7 (2.7-49.9) mm², respectively. Multivariate analysis showed that the CPD values were not significantly different among the treatment groups, although the ostium area differed significantly between the simple and stent-assisted coiling groups (P<.05). Pearson's correlations showed that similar to aneurysm volume, the ostium area was negatively correlated with CPD (r=-0.321, P<.05).

CONCLUSION

In cerebral aneurysms treated with balloon- or stent-assisted coiling, the CPD value does not differ from that in aneurysms treated with simple coiling.

Risk factors for recanalization of dense coil packing for unruptured cerebral aneurysms in endovascular coil embolization: Analysis of a single center's experience

In coil embolization of cerebral aneurysms, inadequate packing is known to increase the probability of recanalization. Even tightly embolized aneurysms may be recanalized, but predictive factors for recanalization have not been fully investigated. This retrospective study aimed to identify risk factors for recanalization of treated aneurysms with a volume embolization ratio (VER) ≥ 25%. A total of 301 unruptured aneurysms in 248 patients who underwent coil embolization between March 2012 and January 2021 were analyzed. Cases involving dissecting aneurysm, intraluminal thrombosis, parent artery occlusion, intraoperative rupture, re-treatment, rupture the day after surgery, postoperative coil migration, and postoperative parent artery occlusion were excluded due to the inaccuracy of VER. A total of 105 aneurysms (34.9%) treated with VER ≥ 25% were extracted. Clinical features (age, sex, medical history, family history), anatomical features (shape, location, aneurysm size, inflow angle, and volume), procedural features (stent-assisted, Raymond-Roy occlusion classification [RROC] immediately after treatment, re-treatment rate), and follow-up period were compared between Recanalization and Non-recanalization groups. Predictors of recanalization were determined using logistic regression and receiver operating characteristic (ROC) curve analyses. Eleven aneurysms were recanalized. In multivariate analysis, RROC class 3 (odds ratio [OR] 11.0; 95% confidence interval [CI] 2.03-59.4) and aneurysm volume (OR 1.005; 95%CI 1.001-1.008) were independent predictors of recanalization. ROC curve analysis showed optimal cutoff values for aneurysm volume of 69.5 mm³ (sensitivity, 81.8%; specificity, 72.3%). In coil embolization of unruptured aneurysms that VER ≥ 25%, cases with RROC class 3 or high aneurysm volume may be associated with a higher risk of recanalization, and should be carefully followed-up.

Evaluation of Surgical Clipping and Endovascular Coiling on Oculomotor Nerve Palsy Caused by Internal Carotid Artery Aneurysm

Objectives: Internal carotid artery (ICA) aneurysm often leads to oculomotor nerve palsy (ONP) that impairs eye movement. Currently, microsurgical clipping and endovascular coiling are the two major options to treat ONP. The purpose of the current study is to compare the clinical outcomes of the two methods in patients with ONP caused by ICA aneurysm. Patients and Methods: In the present study, we assessed the prognostic factors and recovery outcomes of a total of 90 ICA aneurysm-induced ONP patients, where 50 of them were treated with microsurgical clipping and 40 of them were treated with endovascular coiling. Within the endovascular coiling group, 20 of the patients were treated with balloon-assisted coiling and the other 20 were treated with stent-assisted coiling. Results: Overall, we achieved a 59% (53 out of 90) full recovery rate. Both surgical clipping and endovascular coiling treatment methods achieved similar recovery outcomes in the tested patients. However, within the endovascular coiling group, balloon-assisted coiling treatment demonstrated a significantly higher full recovery rate (17 out of 20) compared to stent-assisted coiling treatment (eight out of 20). Conclusion: In general, no significant difference was identified between the surgical and coiling treatments, and both procedures were considered as beneficial for ICA aneurysm-induced ONP.

Three-dimensional aneurysm volume measurements show no correlation between coil packing density and recurrence

Objective

Endovascular treatment is the mainstay therapy for brain aneurysms. About 15% of patients need re-treatment within six months due to early recanalization. In this study, we investigate risk factors associated with treatment failure.

Methods

This retrospective cohort study includes endovascularly treated aneurysm cases between July 2012 and December 2015 at the University of California Davis Medical Center with pre-treatment and early post-treatment imaging. Thin cut 3D aneurysm volume rendering was used for morphologic analyses. Univariate and bivariate analyses were conducted to evaluate differences between patients and clinical factors by treatment failure.

Results

Of the 50 patients who met the inclusion criteria, 41 (82.0%) were female, with an average age of 61 years. Most aneurysms were on the anterior communicating artery (40%) or posterior communicating artery (22.0%), and 34 (68%) aneurysms were ruptured. Early treatment failure was observed in 14 (28.0%) of endovascularly treated patients. Raymond-Roy class (RRC) was significantly associated with treatment failure (p = 0.0052), with 10 out of the 14 cases (71.4%) with early recanalization having an RRC of 3. Coil packing density did not associate with aneurysm recanalization (p = 0.61).

Conclusion

In our single institution series, patient characteristics, aneurysm characteristics, or coil packing density did not affect early aneurysm recanalization. RRC was the best predictor of early recanalization; however, further confirmation with additional studies are required. Although this study focused on early treatment failure, late recanalization has been shown with longer follow up. Further investigation into factors associated with late treatment failure will need further investigation. New intrasaccular devices and flow diverters will also likely play a role in reducing recurrence in the future as these treatments gain usage.

The Relationships between Anatomical Factors and Treatment Procedures for the Endovascular Treatment of Anterior Communicating Artery Aneurysms

Objective

Endovascular treatment of anterior communicating artery aneurysms is difficult due to their complex anatomical structure. We retrospectively analyzed the relationships among the anatomical features, initial microcatheter positions, and initial occlusion outcomes.

Methods

In all, 66 cases were treated at our hospital. We investigated the relationships among the anatomical features of the aneurysm and A1 segment of the anterior cerebral artery (ACA), treatment procedures, and initial occlusion outcomes. We divided the initial microcatheter positions into greater and lesser curvatures based on the curvature from A1 to the aneurysm, and evaluated the outcomes.

Results

In total, 54 out of 66 patients (82%) achieved complete obliteration (CO) or had residual neck (RN) aneurysms, and 12 had residual aneurysms (RAs: 18%). Neck diameters and superior position aneurysms were correlated with initial occlusion outcomes in the multivariate analysis. The relationship between initial occlusion outcomes and initial microcatheter positions in superior position aneurysms (37 patients) was then examined. Eleven out of 26 patients (42.3%) had residual aneurysms at the greater curvature microcatheter position, whereas no residual aneurysms were detected at the lesser curvature microcatheter position. The A1 angle was not correlated with the outcomes.

Conclusion

Wide-necked aneurysms and superior position aneurysms were identified as factors leading to incomplete occlusion in the endovascular treatment of anterior communicating artery aneurysms. The microcatheter position at the greater curvature in superior position aneurysms was a factor for incomplete occlusion. This suggests that guiding the microcatheter to the lesser curvature position of A1 is important in the treatment of superior position aneurysms.

Definitive Treatment With Microsurgical Clipping After Recurrence and Rerupture of Coiled Anterior Cerebral Artery Aneurysms

BACKGROUND

The extent of obliteration of ruptured intracranial aneurysms treated with coil embolization has been correlated with the risk of rerupture. However, many practitioners consider that a small neck remnant is unlikely to result in significant risk after coiling.

OBJECTIVE

To report our recent experience with ruptured anterior cerebral artery aneurysms treated with endovascular coiling, which recurred or reruptured, requiring microsurgical clipping for subsequent treatment.

METHODS

Retrospective review of patients with intracranial aneurysms treated at our institution since August 2018. Patient and aneurysm characteristics, initial and subsequent treatment approaches, and outcomes were reviewed.

RESULTS

Six patients were included. Out of those 6 patients, 5 patients had anterior communicating artery aneurysms, and 1 patient had a pericallosal aneurysm. All initially presented with subarachnoid hemorrhage (SAH) and were treated with coiling. Recurrence occurred at a median of 7.5 mo. In 2 cases, retreatment was initially performed with repeat endovascular coiling, but further recurrence was observed. Rerupture from the residual or recurrent aneurysm occurred in 3 cases. In 2 cases, the aneurysm dome recurred; in 1 case, rerupture occurred from the neck. All 6 patients underwent treatment with microsurgical clipping. Follow-up catheter angiography demonstrated a complete occlusion of the aneurysm in all cases with the preservation of the parent vessel.

CONCLUSION

Anterior cerebral artery aneurysms may recur after endovascular treatment, and even small neck remnants present a risk of rerupture after an initial SAH. Complete treatment requires a complete exclusion of the aneurysm from the circulation. Even in cases that have been previously coiled, microsurgical clipping can represent a safe and effective treatment option.

Safety and efficacy of complete versus near-complete coiling in treatment of intracranial aneurysms

Objective

This study aimed to evaluate the clinical and angiographic outcomes of aneurysms that were completely or near-completely embolized and ascertain whether complete embolization is important in the stent-assisted coiling (SAC) of intracranial aneurysms.

Methods

This retrospective study enrolled 390 patients (417 aneurysms). Among them, complete (100%) or near-complete (>90%) angiographic obliteration of the aneurysms on immediate angiography was accomplished. Baseline characteristics, complications, angiography follow-up results, and clinical outcomes were analyzed.

Results

Cumulative adverse events occurred in 30 patients (7.7%), including thromboembolic complications in 17 (4.4%), intraoperative rupture in 10 (2.6%), and others in 3 (0.8%). Statistical analyses revealed an increased intraprocedural rupture rate in the initial completely occluded aneurysms (5.6% compared with 1.0%). The incidence of cumulative adverse events was higher in patients with completely occluded aneurysms (11.1%) than in those with near-completely occluded aneurysms (5.5%). Angiography follow-up was available for 173 aneurysms. Aneurysm occlusion status at follow-up was correlated with stent placement (p ​= ​0.000, odds ratio ​= ​5.847), size (p ​= ​0.000, odds ratio ​= ​6.446 for tiny aneurysms; and p ​= ​0.001, odds ratio ​= ​5.616 for small aneurysms), and initial aneurysm occlusion status (p ​= ​0.001, odds ratio ​= ​3.436). Complete occlusion at follow-up was seen in 82.6% of the initial complete occlusion group versus 63.0% of the initial near-complete occlusion group. The incidence of complete occlusion at follow-up was higher in the initial completely occluded aneurysms with SAC (100%) than in the initial completely occluded aneurysms with non-SAC (65.2%).

Conclusions

Initial complete treatment may lead to higher complication rates and good clinical outcomes at follow-up. Stent placement may enhance progressive aneurysm occlusion. Initial complete occlusion with SAC can provide durable closure at follow-up.

Efficacy of LVIS vs. Enterprise Stent for Endovascular Treatment of Medium-Sized Intracranial Aneurysms: A Hemodynamic Comparison Study

Background: We conducted a computational fluid dynamics (CFD) study and compared the treatment of medium-sized intracranial aneurysms with LVIS and Enterprise stent-assisted coil embolization (SACE) to determine the effects of hemodynamic changes caused by different stent and coil packing densities (PDs) in endovascular treatment.

Methods: We enrolled 87 consecutive patients, with 87 medium-sized intracranial aneurysms (≥7, ≤ 12 mm), who underwent LVIS or Enterprise SACE. Aneurysms treated with LVIS SACE were allocated to the LVIS group, and the remainder were allocated to the Enterprise group. CFD were performed to assess hemodynamic alterations between before treatment, after stent deployment, and after SACE.

Results: One aneurysm recanalized in the LVIS group (n = 42), and five recanalized in the Enterprise group (n = 45) (recanalization rate: 2.4 vs. 11.1%, respectively; P = 0.108). Higher complete obliteration rate (P = 0.069) was found in the LVIS group. Velocity at the neck plane showed a greater reduction ratio than velocity and WSS of the aneurysm in both groups after stent deployment, while velocity and WSS of the aneurysm showed a greater reduction ratio after coil placement. Further, there was a greater reduction in velocity at the neck plane (59.52 vs. 39.81%), aneurysmal velocity (88.46 vs. 69.45%), and wall shear stress (WSS) (85.45 vs. 69.49%) on the aneurysm in the LVIS group (P < 0.001 for all). Specifically, the reduction ratio of velocity at the neck plane showed significant difference between the groups in the multivariate analysis (P = 0.013).

Conclusions : LVIS SACE showed a lower recanalization for endovascular treatment of medium-sized intracranial aneurysms, and the greater hemodynamic alterations might be the key factors.

The Natural History of Coiled Cerebral Aneurysms Stratified by Modified Raymond-Roy Occlusion Classification

OBJECTIVE

The natural history and long-term durability of Guglielmi detachable coil (GDC) embolization is still unknown. We hypothesize a stepwise decrease in durability of embolized cerebral aneurysms as stratified by the Modified Raymond-Roy Classification (MRRC).

METHODS

First-time GDC-embolized cerebral aneurysms were retrospectively reviewed from 2004 to 2015. Loss of durability (LOD) was defined by change in aneurysm size or patency seen on serial radiographic follow-up. Kaplan-Meier survival analysis was performed to evaluate embolization durability. Multivariate Cox regression modeling was used to assess baseline aneurysm and patient characteristics for their effect on LOD.

RESULTS

A total of 427 patients with 443 aneurysms met the inclusion criteria. Overall, 89 (21%) aneurysms met LOD criteria. Grade 1 aneurysms had statistically significantly greater durability than did all other MRRC grades. Grade 3b aneurysms had significantly worse durability than did all other aneurysm grades. There was no difference in durability between grade 2 and 3a aneurysms. Of aneurysms with LOD, 26 (29%) experienced worsening of MRRC grade. Thirty-five (24%) initial MRRC grade 2, 72 (45%) initial MRRC grade 3a, and 6 (22%) initial MRRC grade 3b aneurysms progressed to MRRC grade 1 without retreatment. In our multivariate analysis, only initial MRRC grade was statistically significantly associated with treatment durability (P < 0.001).

CONCLUSIONS

MRRC grade is independently associated with first-time GDC-embolized cerebral aneurysm durability. Achieving MRRC grade 1 occlusion outcome is significantly associated with greater long-term GDC durability. Although few aneurysms experience further growth and/or recanalization, most incompletely obliterated aneurysms tend to remain stable over time or even progress to occlusion. Grading scales such as the MRRC are useful for characterizing aneurysm occlusion but may lack sensitivity and specificity for characterizing changes in aneurysm morphology over time.

Initial experience and one-year follow-up with Neuroform Atlas Stent System for the treatment of brain aneurysms

INTRODUCTION

The Neuroform Atlas Stent System is a recently introduced modification of the original Neuroform Stent System consisting of a hybrid design with open and closed cells. Initial experience, technical considerations and treatment outcomes including 1-year follow-up using the Atlas stent in combination with coil embolization are reported.

MATERIAL AND METHODS

Thirty patients with 30 unruptured aneurysms were treated with stent reconstruction. Immediate, 4-month and 12-month post-treatment angiography and clinical assessment were performed.

DISCUSSION

In 29 cases, the stents were delivered and positioned without difficulty in deployment. Technical complications occurred in one patient related to advancement of the stent during delivery. One procedure-related clinical complication occurred with no permanent neurological deficit. On immediate post-treatment angiography, 29 of 30 aneurysms showed Raymond Class I or Class II occlusion. At 1-year follow-up, all 30 patients were clinically stable and 18 of 30 aneurysms showed Raymond Class I complete occlusion. Retreatment was performed in two patients with residual aneurysm.

CONCLUSIONS

The Atlas stent is technically safe and simple to implant and has a low thrombogenic potential. We experienced fewer problems associated with deployment and implantation, thromboembolic complications and hemorrhagic events compared with other types of stents, including braided stents. However, because of its low thrombogenic potential, partially occluded aneurysms or those with aneurysm remnants do not progress to complete occlusion.

Comparison of Stent-Assisted Coil Placement and Coiling-Only for the Treatment of Ruptured Intracranial Aneurysms

Background

The use of a stent during the acute post-hemorrhage period is controversial. We conducted a retrospective analysis on the clinical and angiographic outcomes of the ruptured aneurysms that were embolized with stent-assisted coiling or coiling-only.

Material/Methods

We reviewed data of 279 patients with 279 ruptured intracranial aneurysms who underwent coil embolization between July 2004 and June 2015. The baseline data on age, sex, medical history, aneurysm size, location, and Hunt and Hess grade were recorded.

Results

One hundred and thirteen aneurysms were treated with stent-assisted coiling. Adverse events occurred in similar proportions of patients in the two groups (11.5% in the stenting group and 9.0% in the coiling alone group). The incidence of permanent disabling neurologic deficit was also similar in the two groups (7.1% and 5.4% in the stenting group and coiling alone group respectively). Clinical follow-up data were available in 207 patients with a median period of 28 months. Angiographic follow-up was available in 106 aneurysms with a median period of 7.5 months. Clinical outcomes were correlated with adverse events (p=0.043, odds ratio=4.59), large aneurysms (p=0.013, odds ratio=10.24), and Hunt and Hess grade (p=0.001, odds ratio=13.51). Stent-assisted coiling for ruptured aneurysm, as compared with coiling-only, was not associated with an increased incidence of poor clinical outcome at follow-up. Aneurysm-occlusion status at follow-up were correlated with stent placement (p<0.001, odds ratio=5.85) and initial aneurysm-occlusion status (p=0.027, odds ratio=3.78).

Conclusions

Compared with coiling-only, stent-assisted coil placement may have better durability, with comparable safety for ruptured intracranial aneurysm.

Temporary Stent-Assisted Coil Embolization as a Treatment Option for Wide-Neck Aneurysms

BACKGROUND AND PURPOSE

Simple coil embolization is often not a feasible treatment option in wide-neck aneurysms. Stent-assisted coil embolization helps stabilize the coils within the aneurysm. Permanent placement of a stent in an intracranial vessel, however, requires long-term platelet inhibition. Temporary stent-assisted coiling is an alternative technique for the treatment of wide-neck aneurysms. To date, only case reports and small case series have been published. Our purpose was to retrospectively analyze the effectiveness and safety of temporary stent-assisted coiling in a larger cohort.

MATERIALS AND METHODS

Research was performed for all patients who had undergone endovascular aneurysm treatment in our institution (University Hospital Aachen) between January 2010 and December 2015. During this period, 355 consecutive patients had undergone endovascular aneurysm treatment. We intended to treat 33 (9.2%) of them with temporary stent-assisted coiling, and they were included in this study. Incidental and acutely ruptured aneurysms were included.

RESULTS

Sufficient occlusion was achieved in 97.1% of the cases. In 94%, the stent could be fully recovered. Complications occurred in 5 patients (14.7%), whereas in only 1 case was the complication seen as specific to stent-assisted coiling.

CONCLUSIONS

Temporary stent-assisted coiling is an effective technique for the treatment of wide-neck aneurysms. Safety is comparable with that of stent-assisted coiling and coiling with balloon remodeling.

Analysis of endovascular treatment of ruptured aneurysms of the middle cerebral artery compared to other anatomical locations

OBJECTIVE

The objective of this article is to compare the results of endovascular treatment of ruptured middle cerebral artery (MCA) aneurysms with ruptured aneurysms of other anatomic locations.

METHODS

Fifty consecutive ruptured aneurysms of the MCA and 209 aneurysms at other anatomical locations were selected retrospectively. We compared epidemiological, clinical and radiological variables, prognosis and complications.

RESULTS

The MCA aneurysms had a greater size and a poor dome/neck ratio. There were no significant differences in endovascular technique complications, occlusion rate or rebleeding between the two groups (p > 0.1). There were no significant differences in the mortality and number of dependent patients after one month.

CONCLUSION

The endovascular treatment of ruptured MCA aneurysms without hematoma is as safe and effective as other aneurysm localizations. Complication rates, occlusion rates and rebleeding of ruptured MCA aneurysms are comparable to other locations.

Large Residual Volume, Not Low Packing Density, Is the Most Influential Risk Factor for Recanalization after Coil Embolization of Cerebral Aneurysms

Background

Tight coil packing with density of at least 20%–25% is known to be important for preventing recanalization after embolization of cerebral aneurysms. However, large aneurysms sometimes recanalize regardless of the packing density, suggesting that the absolute residual volume which is determined by aneurysm volume and packing density may be more important risk factor for recanalization. To validate this hypothesis, we analyzed the factors affecting the outcomes of treated aneurysms at our institute.

Methods and Findings

We included 355 small and large aneurysms. The following six factors were obtained from every case: aneurysm volume (mL), neck size (mm), packing density (%), residual volume (mL), rupture status at presentation, and stent assistance (with or without stent). The data were then subjected to multivariate logistic regression analysis to identify significant risk factors for recanalization. Recanalization occurred in 61 aneurysms (17.2%). Significant predictors for recanalization were aneurysm volume (odds ratio, 15.3; P < 0.001) and residual volume (odds ratio, 30.9; P < 0.001), but not packing density (odds ratio, 0.98; P = 0.341). These results showed that for each 0.1-mL increase in aneurysm volume and residual volume, the risk of recanalization increased by 1.3 times and 1.4 times, respectively.

Conclusions

The most influential risk factor for recanalization after coil embolization was residual volume, not packing density. The larger the aneurysm volume, the greater the packing density has to be to minimize the residual volume and risk of recanalization. Since tight coil packing has already been aimed, further innovation of coil property or embolization technique may be needed. Otherwise, different treatment modality such as flow diverter or parent artery occlusion may have to be considered.

Predictors of success following endovascular retreatment of intracranial aneurysms

INTRODUCTION

Although approximately one in every 10 patients undergoing coil embolization of intracranial aneurysms requires retreatment, the factors that are associated with outcome following retreatment remain to be fully elucidated.

METHODS

This is a single-center, retrospective review of 43 patients with 58 intracranial aneurysms that were retreated from 2004 to 2014. Aneurysms undergoing first time or microsurgical retreatment were excluded. Retreatment types were grouped into those without permanent parent vessel support (stand-alone and balloon-assisted coiling) versus those with permanent parent vessel support (stent-assisted coiling, stand-alone stenting, and flow diversion). The Modified Raymond Roy Classification was used to group aneurysms at all angiographic follow-up points either in the successful outcome group (Class I or II) or the unsuccessful outcome group (Class IIIa or IIIb).

RESULTS

Of aneurysms with follow-up, 50% were in the successful group and 50% in the unsuccessful group. In univariate analysis, small aneurysm size (p < 0.001), previous treatment type (p = 0.022), retreatment type (p = 0.001), and initial occlusion class (p = 0.005) were all associated with angiographic outcome. In multivariate analysis, small aneurysm size (p = 0.005, odds ratio (OR) 24.56, confidence interval (CI) 2.68-225.4) and retreatment type with permanent parent vessel support, namely stent-assisted coiling (p = 0.017, OR 31.1, CI 1.89-517.7), were associated with retreatment success.

CONCLUSIONS

Small aneurysm size and retreatment with permanent parent vessel support, namely stent-assisted coiling, are predictors of success following endovascular retreatment of intracranial aneurysms. These findings could be useful in the effort to both prevent and predict treatment failure following endovascular retreatment.