Embolization of very small (≤3 mm) unruptured intracranial aneurysms: A large single-center experience on treatment of unruptured versus ruptured cases

Endovascular Coiling of Ruptured Tiny Saccular Intracranial Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND

The safety and efficacy of endovascular coiling of ruptured tiny saccular intracranial aneurysms (IAs) (≤3 mm) remain unknown.

METHODS

A comprehensive search of PubMed, Embase, Web of Science, and Scorpus databases up to November 15, 2023 was performed. Pooled prevalence was calculated for occlusion rates, recanalization, retreatment, long-term favorable outcome, and procedure-related complications and mortality. Pooled odds ratios were calculated to compare these outcomes between coiling and stent-assisted coiling (SAC).

RESULTS

Forty-two studies with 2166 ruptured tiny saccular IAs treated with coiling were included. The follow-up complete aneurysm occlusion rate was 83.9% (95% CI: 77.2-88.9%). The rates of recanalization and retreatment were 7.7% (95% CI: 5.7-10.2%) and 5.8% (95% CI: 4.5-7.5%). The range of median Hunt and Hess grades was 1.4-2.9 and the favorable outcome rate was 85.6% (95% CI: 81.1-89.2%). The rates of thromboembolism, intraprocedural rupture, and mortality were 4.6% (95% CI: 3.6-5.8%), 5.4% (95% CI: 4.1-7.0%), and 5.6% (95% CI: 4.4-7.2%), respectively. Comparison of coiling and SAC revealed no significant difference, except for a higher likelihood of follow-up complete aneurysm occlusion in SAC (odds ratio [OR] 0.37, 95% CI: 0.17-0.80) and recanalization in the coiling (OR, 3.21 [95% CI, 1.37-7.51]).

CONCLUSIONS

Our meta-analysis demonstrates that coiling for ruptured tiny saccular IA is a feasible, effective, and safe approach that is associated with favorable clinical outcomes in both the short and long term for patients with mild to moderate Hunt and Hess grades.

Morphological Factors affecting Coil-Only Embolization of Small Unruptured Aneurysms

Objective When small unruptured aneurysms (SUA) are embolized by coils, manipulation of the microcatheter and coil is limited because of their small size. Previous studies suggested that the morphology of the artery and aneurysm is important. In the present study, we clarified the morphological factors affecting coil-only embolization of SUA.

Patients and Methods We retrospectively identified 17 patients who underwent embolization for unruptured aneurysm with a maximum diameter less than 5 mm. We investigated the following: (1) the relationships among dome/neck ratio (D/N), height/neck ratio (H/N), height/dome ratio (H/D), projection of aneurysm-parent artery, and adverse events, (2) immediate and late occlusion, and (3) number of coils.

Results (1) Adverse events developed in three cases in which the H/D was smaller than 1 (p < 0.02). There was a significant difference in the rate of adverse events by projection of the aneurysm-parent artery (p < 0.03), (2) Occlusion rate: Immediately after coil embolization, 71% (12/17) were neck remnant; however, 88% (15/17) of SUA became complete occlusion in the follow-up term, and (3) 1.5 ± 0.6 coils were used.

Conclusion To achieve successful coil-only embolization in SUAs, it is important to select aneurysms for which the projection of the parent artery is suitable for embolizing and the H/D ratio is larger than 1. In SUAs, occlusion develops naturally after coil embolization.

Evolution of open surgery for unruptured intracranial aneurysms over a fifteen year period-increased difficulty and morbidity

OBJECTIVE

The approach to intervention for unruptured intracranial aneurysms (UIAs) remains controversial. Utilization of endovascular techniques for aneurysm repair increased dramatically during the last decade. We sought to analyze recent national trends for electively treated (open and endovascular) UIAs focusing on pre-existing patient disease burden and intervention modality selection.

METHODS

The Nationwide Inpatient Sample (NIS) national database was used to identify patients with primary diagnosis codes of unruptured intracranial aneurysm between 1999 and 2014. Patients were dichotomized by intervention into endovascular or open surgical treatment. Analysis of pre-existing disease severity were calculated using the Elixhauser comorbidity index. Complications of combined peri-procedural stroke or death during admission and hospital length of stay were used as primary endpoints for comparison.

RESULTS

The percent of total UIAs treated electively with open approach decreased from more than 95 % of cases in 1999 to less than 25 % in 2014. Patients undergoing clipping were 3 years younger than those in the endovascular group (p < 0.001). The rate of primary endpoint complications (stroke and death) and length of stay for open cases saw a decrease throughout the study but remained statistically higher when compared to the endovascular group over the study period (p < 0.001). Additionally, non-neurologic complications increased over the time period for open cases. The average preoperative co-morbid disease severity for all groups treated increased over this interval. Conversely, the relative volume of endovascular cases increased but the rate of complications and average group disease remained statistically lower than the surgical clipping group (p < 0.05).

CONCLUSION

The percent of UIAs treated electively with open approach has decreased since 1999 with a concomitant increase in complication rate in particular compared to endovascular cases. However, the health characteristics of patients treated with surgical clipping show an increase in severity of pre-existing co-morbidities. Further research into factors contributing to this finding, including potential socioeconomic differences and changes in surgeon experience are needed.

Different Hemodynamic Characteristics and Resulting in Different Risks of Rupture Between Wide-Neck and Narrow-Neck Aneurysms

Objective

This study aimed to determine the ruptured rate and hemodynamic difference between wide-neck aneurysms (WNAs) and narrow-neck aneurysms (NNAs), as well as the hemodynamic parameters of risk factors for aneurysm rupture.

Methods

A total of 121 cases of intracranial aneurysms (IAs) were studied retrospectively between January 2019 and April 2021 at Renmin Hospital of Wuhan University. Intracranial aneurysms were classified into four types: ruptured wide-neck aneurysms (RWNAs), unruptured wide-neck aneurysms (UWNAs), ruptured narrow-neck aneurysms (RNNAs), and unruptured narrow-neck aneurysms (UNNAs). The Chi-square test was used to compare differences in rupture ratios. The clinical characteristics and hemodynamics were analyzed statistically to reveal the rupture risk factors. Moreover, significant parameters were subjected to binary logistic regression analysis to identify the independent predictive factors. The receiver operating characteristic (ROC) curve was performed to obtain cutoff values.

Results

WNAs ruptured more frequently than NNAs (P = 0.033). Ruptured intracranial aneurysms (RIAs) were characterized by significantly higher intra-aneurysmal pressure (IAP), wall shear stress (WSS), wall shear stress gradient (WSSG), and lower normalized wall shear stress (NWSS) than unruptured intracranial aneurysms (UIAs). RWNAs had higher IAP, WSS, and lower NWSS than UWNAs (P < 0.05). RNNAs had higher IAP, Streamwise WSSG and lower NWSS compared to UNNAs (P < 0.05). Binary logistic regression revealed that IAP and WSS were independent predictive risk factors for WNAs rupture, with cut-off values of 405.5 and 6.66 Pa, respectively. Also, IAP was an independent predictive risk factor for NNA rupture, with a cut-off value of 255.3 Pa.

Conclusions

Wide-neck aneurysms and narrow-neck aneurysms have diverse hemodynamics, which prompts a higher rupture ratio for WNAs. IAP could characterize the rupture risk in both WNAs and NNAs independently, but WSS could only predict the rupture risk in WNAs. This research might assist neurosurgeons with fostering a more sensible strategy for the treatment of IAs.

Endovascular Treatment of Ruptured Very Small Intracranial Aneurysms: Complications, Recurrence Rate, and Clinical Outcomes

Objective: The aim of this study was to evaluate the safety and efficacy of endovascular treatment for ruptured very small (≤3 mm) intracranial aneurysms (VSIAs).

Methods: The clinical data and imaging results for 152 patients with VSIAs treated with coil embolization from August 2014 to June 2020 were retrospectively reviewed. The influential factors related to the preoperative complications, aneurysm recurrence, and clinical outcomes for these patients were analyzed.

Results: Among 152 patients with ruptured VSIAs, 90 were treated with coil embolization alone, while 62 were treated with stent-assisted coil embolization. Eighteen patients experienced intra and/or postoperative complications (overall incidence = 11.8%). One person died of intraoperative aneurysm re-rupture and postoperative rebleeding (mortality rate = 0.65%). Twenty patients had various degrees of neurological dysfunction (morbidity rate = 13.1%). Statistical analysis showed that there was no independent risk factor associated with perioperative complications. The rate of complete aneurysm occlusion at discharge and follow-up was 76.3 and 86.2%, respectively. A total of 105 patients underwent digital subtraction angiography during follow-up, and 18 of them experienced postoperative recurrence (recurrence rate = 17.1%). Seven patients were retreated (retreatment rate = 6.7%). The use of stents was the only factor that affected the postoperative recurrence of aneurysm. The incidence of favorable clinical outcomes (Glasgow Outcome Scale score ≥ 4) at discharge and follow-up was 86.2 and 97.1%, respectively. Univariate analysis showed that the preoperative Hunt-Hess grade, CT Fisher grade, and perioperative complications were risk factors for poor clinical outcomes. Multiple logistic regression analysis showed that perioperative complication was the most significant risk factor for the clinical prognosis of patients with ruptured VSIAs.

Conclusion: Endovascular treatment is a safe and efficient approach for ruptured VSIAs. Stent-assisted coiling reduced the recurrence rate of aneurysm without increasing the incidence of perioperative complications. The Hunt-Hess grade, CT Fisher grade, and perioperative complications were independent factors associated with the clinical outcomes of patients with ruptured VSIAs, and perioperative complication was the most significant risk factor for poor prognosis in patients.

The Safety and Efficacy of Endovascular Treatment for Very Small Ruptured Anterior Communicating Artery Aneurysms: A Large Single-Center Experience With 81 Consecutive Cases

OBJECTIVE

This study aimed to investigate the safety and efficacy of endovascular embolization for very small ruptured anterior communicating artery (AcomA) aneurysms.

METHODS

From August 2015 to June 2020, 81 patients with very small (≤3 mm) ruptured AcomA aneurysms treated endovascularly were enrolled in this study. Clinical and radiographic data were analyzed retrospectively, including the aneurysm occlusion rate, complications, and clinical outcome.

RESULTS

Among 81 patients, simple coiling embolization was performed in 52 cases and stent-assisted embolization in 29 cases. Immediate angiography demonstrated complete occlusion in 59 (72.8%) aneurysms, residual neck in 20 (24.7%) aneurysms, and residual lumen in 2 (2.5%). Procedure-related complications rate was 2.5% (2 of 81), all of which were transient thromboembolic events. Angiographic follow-up outcomes of 60 patients (mean: 6.8 ± 3.2 months) revealed complete occlusion in 91.7% (55 of 60), with recurrence in 1 patient. The mean clinical follow-up time was 22.6 ± 11.4 months and good prognosis rates (6-month modified Rankin Scale score: 0-2) reached 90.2% (73 of 81). The differences in aneurysm occlusion and procedure-related complications between the simple coiling group and the stent-assisted coiling group were not statistically significant.

CONCLUSIONS

Coiling with or without stent-assisted technique for the treatment of very small ruptured AcomA aneurysms was safe and effective.

Endovascular Treatment of Tiny Aneurysms With Low-Profile Visualized Intraluminal Support Devices Using a "Compressed" Stent Technique

Objective: To investigate the safety and efficacy of low-profile visualized intraluminal support (LVIS) stent-assisted coiling of intracranial tiny aneurysms using a "compressed" stent technique. Methods: We retrospectively analyzed patients with tiny aneurysms treated in our hospital with LVIS devices using a compressed stent technique. We analyzed patients' imaging outcomes, clinical outcomes, and complications. Results: Forty-two tiny aneurysms in 42 patients were included in this study cohort; 8 patients presented with subarachnoid hemorrhage at admission. The immediate postoperative complete embolization rate was 76.2% (32/42). After an average of 8.5 months of imaging follow-up, the complete embolization rate was 90.5% (38/42), and no aneurysm recanalization occurred. After an average of 24.4 months of clinical follow-up, 95.2% (40/42) of the patients achieved favorable clinical outcomes (modified Rankin scale = 0/1). Operation-related complications occurred in two patients (4.8%); one intraoperative acute thrombosis, and one significant unilateral decreased vision during the postoperative follow-up. Conclusion: LVIS stent-assisted coiling of intracranial tiny aneurysms using a compressed stent technique is safe and effective. Combined stent compression technology is beneficial to maximize the complete embolization of aneurysms and reduce aneurysm recanalization. This study expands the clinical applicability of LVIS stents.