Treatment of intracranial aneurysms by embolization with coils: a systematic review

Deep learning and machine learning predictive models for neurological function after interventional embolization of intracranial aneurysms

Objective

The objective of this study is to develop a model to predicts the postoperative Hunt-Hess grade in patients with intracranial aneurysms by integrating radiomics and deep learning technologies, using preoperative CTA imaging data. Thereby assisting clinical decision-making and improving the assessment and prognosis of postoperative neurological function.

Methods

This retrospective study encompassed 101 patients who underwent aneurysm embolization surgery. 851 radiomic features were extracted from CTA images. 512 deep learning features are extracted from last layer of ResNet50 deep convolutional neural network model. The feature screening process pipeline encompassed intraclass correlation coefficient analysis, principal component analysis, U test, spearman correlation analysis, minimum redundancy maximum relevance algorithm and Lasso regression, to identify features most correlated with postoperative Hunt-Hess grading. In the model construction phase, three distinct models were constructed: radiomics feature-based model (RSM), deep learning feature-based model (DLM), and deep learning-radiomics feature fusion model (DLRSCM). The study also calculated the radiomics score and combined it with clinical data to construct a Nomogram for predictive modeling. DLM, RSM and DLRSCM model was constructed by 9 base algorithms and 1 ensemble learning algorithm - Stacking ensemble model. Model performance was evaluated based on the area under the Receiver Operating Characteristic (ROC) curve (AUC), Matthews Correlation Coefficient (MCC), calibration curves, and decision curves analysis.

Results

5 significant radiomic feature and 4 significant deep learning features were obtained through the feature selection process. These features were utilized for model construction. Bootstrap resampling method was used for internal validation of the models. In terms of model evaluation, the DLM model, the stacking ensemble algorithm results achieved an AUC of 0.959 and MCC of 0.815. In the RSM model, the stacking ensemble model AUC was 0.935 and MCC was 0.793. The stacking ensemble model in DLRSCM outperformed others, with an AUC of 0.968 and MCC of 0.820. Results indicated that the ANN performed optimally among all base models, while the stacked ensemble learning model exhibited the highest predictive performance.

Conclusion

This study demonstrates that the combination of radiomics and deep learning is an effective approach to predict the postoperative Hunt-Hess grade in patients with intracranial aneurysms. This holds significant value in the early identification of postoperative neurological complications and in enhancing clinical decision-making.

Surgery or Endovascular Treatment in Patients with Anterior Communicating Artery Aneurysm: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE

Although randomized controlled trials have compared surgery versus endovascular treatment for intracranial aneurysms, the literature is sparse in terms of subgroup analysis for anterior communicating artery (ACoA) aneurysm management. This systematic review and meta-analysis sought to compare surgical versus endovascular treatment for ACoA aneurysms.

METHODS

Medline, PubMed, and Embase were searched from inception to December 12, 2022. Primary outcomes were post-treatment modified Rankin Scale (mRS) >2 and mortality. Secondary outcomes were aneurysm obliteration, retreatment and recurrence, rebleeding, technical failure, vessel rupture, aneurysmal subarachnoid hemorrhage-related hydrocephalus, symptomatic vasospasm, and stroke.

RESULTS

Eighteen studies yielded 2368 patients, from which 1196 (50.5%) and 1172 (49.4%) patients underwent surgery and endovascular treatment, respectively. The odds ratio (OR) of mortality was similar in total (OR = 0.92 [0.63-1.37], P = 0.69), ruptured (OR = 0.92 [0.62-1.36], P = 0.66), and unruptured cohorts (OR = 1.58 [0.06-39.60], P = 0.78). The OR of mRS > 2 was similar in total (OR = 0.75 [0.50-1.13], P = 0.17), ruptured (OR = 0.77 [0.49-1.20], P = 0.25), and unruptured cohorts (OR = 0.64 [0.21-1.96], P = 0.44). The OR of obliteration was higher with surgery in the total (OR = 2.52 [1.49-4.27], P = 0.0008) and ruptured cohorts (OR = 2.61 [1.33-5.10], P = 0.005) and unruptured group (OR = 3.46 [1.30-9.20], P = 0.01). The OR of retreatment was lower with surgery in the total (OR = 0.37 [0.17-0.76], P = 0.007) and ruptured cohorts (OR = 0.31 [0.11-0.89], P = 0.03), thought it was similar in the unruptured group (OR = 0.51 [0.08-3.03], P = 0.46). The OR of recurrence was lower with surgery in the total (OR = 0.22 [0.10, 0.47], P = 0.0001), ruptured (OR = 0.16 [0.03, 0.90], P = 0.04), and mixed (un) ruptured cohorts (OR = 0.22 [0.09-0.53], P = 0.0009). The OR of rebleeding in ruptured group was similar (OR = 0.66 [0.29-1.52], P = 0.33). The ORs of other outcomes were similar.

CONCLUSIONS

ACoA aneurysms may be safely treated with either surgery or endovascular treatment, although microsurgical clipping demonstrates higher obliteration rates and lower rates of retreatment and recurrence.

Near Infrared-Absorbing Nanoparticle-Mediated Endovascular Photothermal Precision Embolization of Tumor Feeding Vessels for Starvation Treatment

Photothermal therapy has attracted enormous attention as an efficient treatment modality in cancer ablation but still encounters a major bottleneck due to the limited penetration depth of light inside tissues. To overcome the challenge of deep tissue penetration, we present a strategy of endovascular photothermal precision embolization (EPPE), which employs an endovascular optical fiber to induce local embolization only in the entrance of feeding vessels through photothermal heating for the purpose of fully blocking the blood supply of the whole tumor. In EPPE, we apply a highly efficient and biocompatible photothermal agent, i.e., near-infrared (NIR)-light-absorbing diketopyrrolopyrrole-dithiophene-based nanoparticle, which exhibits a high cell-killing efficacy at a concentration of 200 μg/mL using 808 nm laser irradiation of 0.5 W/cm² within 5 min in both 2D cell culture and a 3D tumor spheroid model. We verify the feasibility of EPPE in an ex vivo organ-structured recellularized liver model and further confirm the in vivo efficacy of the photothermal treatment in a rat liver model. The photothermal treatment combined with the embolization effect holds promise to serve as an effective starvation therapy to treat tumors of varying sizes and locations.

Retrieval of Migrated Coils From Distal Cerebral Vasculature Using Stent Retriever: A Case Series

The incidence of coil dislocation during an endovascular embolization of intracranial aneurysm is low but it can lead to serious thrombo-embolic complications. Therefore, coil displacement/migration often requires either retrieval or fixation of the errant coil with a stent. There are no standard recommended methods of coil retrieval. We present a series of three cases in which off-label application of a stent retriever allowed successful retrieval of herniated coils.

Worldwide productivity and research trends of publications concerning stent application in acutely ruptured intracranial aneurysms: A bibliometric study

Background

Stenting is a common clinical practice to treat acutely ruptured intracranial aneurysm (RIA). Although multiple studies have demonstrated its long-term safety and effectiveness, there is currently a lack of bibliometric analysis on stent application in acutely RIA. This study sought to summarize the current status of research in this field and lay a foundation for further study.

Materials and methods

Related publications were searched in the Web of Science Core Collection (WoSCC) database. Data analysis and visualization were performed by R and CiteSpace software.

Results

A total of 275 publications published in English from 1997 to 2022 were included in this study. The growth of publications slowed down. The reference co-citation network identified 13 clusters with a significant network (Q = 0.7692) and convincing clustering (S = 0.9082). The research focus was acutely RIA and the application of stents during interventional procedures. The main trends of research were: (1) development of materials, and (2) safety of stent application in acutely RIA. The United States contributed the most articles, and Jianmin Liu was the most prolific author. Mayo Clinic was the leading institution in this field. Most articles were published in Interventional Neuroradiology.

Conclusions

This study analyzed the research trends, hotspots and frontiers of stent application in acutely RIA. It is our hope that the results obtained could provide useful information to researchers to get a clearer picture about their future research directions in this field.

Predictors of Ischemic Complication in Anterior Choroidal Artery Aneurysm Repair

BACKGROUND

Treatment of anterior choroidal artery (AchoA) aneurysms is challenging because of the risk of artery injury. The objective of the study was to evaluate the incidence and predictors of AchoA infarction in patients who underwent surgical or endovascular procedure.

METHODS

We included 123 patients with AchoA aneurysms treated by surgical clipping (n = 62; 50.4%) or endovascular coiling, including flow diverter placement (n = 61; 49.6%). The clinical and radiological data were retrospectively analyzed. AchoA infarction was defined as the presence of a hyperintense signal on diffusion-weighted imaging in the area of AchoA, including the posterior limb of the internal capsule.

RESULTS

AchoA infarction was detected in 8 cases (6.5%), with similar incidence in both groups (6.5% [4/62] vs. 6.6% [4/61]). It occurred in ruptured aneurysms more frequently than in unruptured aneurysms (14.3% [6/42] vs. 2.5% [2/81], P = 0.019). In the surgical group, all 4 affected patients had a non-proximal type AchoA, whereas in the non-infarction group, 9 patients (15.5%) had a non-proximal type AchoA (P = 0.001). In the endovascular group, the incidence was higher in patients with ruptured aneurysms (17.3% [4/23] vs. 0% [0/38], P = 0.017) and lower in patients with pre-admission antiplatelet therapy (0% [0/39] vs. 18.8% [4/22], P = 0.014).

CONCLUSIONS

Repair of an AchoA aneurysm is associated with the risk of incurring post-procedural AchoA infarction. Surgical clipping and endovascular coiling have similar complication rates, but risk factors specific to each intervention exist. Careful surgical planning to avoid these risk factors in each therapeutic modality may improve patient outcomes.

A Cohesive Shear-Thinning Biomaterial for Catheter-Based Minimally Invasive Therapeutics

Shear-thinning hydrogels are suitable biomaterials for catheter-based minimally invasive therapies; however, the tradeoff between injectability and mechanical integrity has limited their applications, particularly at high external shear stress such as that during endovascular procedures. Extensive molecular crosslinking often results in stiff, hard-to-inject hydrogels that may block catheters, whereas weak crosslinking renders hydrogels mechanically weak and susceptible to shear-induced fragmentation. Thus, controlling molecular interactions is necessary to improve the cohesion of catheter-deployable hydrogels. To address this material design challenge, we have developed an easily injectable, nonhemolytic, and noncytotoxic shear-thinning hydrogel with significantly enhanced cohesion via controlling noncovalent interactions. We show that enhancing the electrostatic interactions between weakly bound biopolymers (gelatin) and nanoparticles (silicate nanoplatelets) using a highly charged polycation at an optimum concentration increases cohesion without compromising injectability, whereas introducing excessive charge to the system leads to phase separation and loss of function. The cohesive biomaterial is successfully injected with a neuroendovascular catheter and retained without fragmentation in patient-derived three-dimensionally printed cerebral aneurysm models under a physiologically relevant pulsatile fluid flow, which would otherwise be impossible using the noncohesive hydrogel counterpart. This work sheds light on how charge-driven molecular and colloidal interactions in shear-thinning physical hydrogels improve cohesion, enabling complex minimally invasive procedures under flow, which may open new opportunities for developing the next generation of injectable biomaterials.

Safety and Efficacy of Endovascular Embolization of Ruptured Intracranial Aneurysms within 72 hours of Subarachnoid Hemorrhage

PURPOSE

 The purpose of the study was to investigate the safety and efficacy of endovascular embolization of ruptured intracranial aneurysms within 72 hours of subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

 Patients with intracranial aneurysms treated with embolization were divided into group A (n = 277), patients with ruptured aneurysms treated within 72 hours of SAH; group B (n = 138), patients with ruptured aneurysms treated beyond 72 hours; and group C (n = 93), patients with unruptured aneurysms.

RESULTS

 Embolization was successful in all but four patients (99.2%). The periprocedural complication rate was 36.2% in group B, significantly (p < 0.05) greater than that in group A (24.5%) or group C (11.8%). The rebleeding rate was 9.7% (6/62 patients) in groups A and B after embolization and only 0.3% (1/346 patients) in aneurysms with total or subtotal occlusion. Of these three groups of patients, 69.7% in group A, 58.7% in group B, and 76.3% in group C achieved Glasgow Outcome Scale (GOS) score of 5 or modified Rankin Scale (mRS) score of 0- to 1 at discharge. A significant difference (p < 0.05) existed in the clinical outcome between the three groups. The percentages of patients without deficits (GOS 5 or mRS 0-1) and slight disability (mRS 2) were 80.2% in group A, 81.2% in group B, and 96.7% in group C. The mortality rate was 4.3% (12/277 patients) in group A and 7.2% (10/138 patients) in group B with no significant (p = 0.21) difference. Follow-up was performed at 3 to 54 months (mean 23.2), and the recanalization rate was 28.6% (32/112 patients) in group A, 22.4% (11/49 patients) in group B, and 28.6% (16/56 patients) in group C, with no significant differences (p = 0.15). Hydrocephalus occurred in 30.5% (39/128 patients) in group B, which was significantly (p < 0.01) greater than that in group A (9.4%) or group C (2.2%).

CONCLUSION

 Early embolization of ruptured cerebral aneurysms within 72 hours of rupture is safe and effective and can significantly decrease periprocedural complications compared with management beyond 72 hours. Timely management of cisternal and ventricular blood can reduce hydrocephalus incidence and improve prognosis.

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.

High-resolution image-guided WEB aneurysm embolization by high-frequency optical coherence tomography

BACKGROUND

High-frequency optical coherence tomography (HF-OCT) is an intra-vascular imaging technique capable of assessing device-vessel interactions at spatial resolution approaching 10 µm. We tested the hypothesis that adequately deployed Woven EndoBridge (WEB) devices as visualized by HF-OCT lead to higher aneurysm occlusion rates.

METHODS

In a leporine model, elastase-induced aneurysms (n=24) were treated with the WEB device. HF-OCT and digital subtraction angiography (DSA) were performed following WEB deployment and repeated at 4, 8, and 12 weeks. Protrusion (0-present, 1-absent) and malapposition (0-malapposed, 1-neck apposition >50%) were binary coded. A device was considered 'adequately deployed' by HF-OCT and DSA if apposed and non-protruding. Aneurysm healing on DSA was reported using the 4-point WEB occlusion score: A or B grades were considered positive outcome. Neointimal coverage was quantified on HF-OCT images at 12 weeks and compared with scanning electron microscopy (SEM).

RESULTS

Adequate deployment on HF-OCT correlated with positive outcome (P=0.007), but no statistically significant relationship was found between good outcome and adequate deployment on DSA (P=0.289). Absence of protrusion on HF-OCT correlated with a positive outcome (P=0.006); however, malapposition alone had no significant relationship (P=0.19). HF-OCT showed a strong correlation with SEM for the assessment of areas of neointimal tissue (R²=0.96; P<0.001). More neointimal coverage of 78%±32% was found on 'adequate deployment' cases versus 31%±24% for the 'inadequate deployment' cases (P=0.001).

CONCLUSION

HF-OCT visualizes features that can determine adequate device deployment to prognosticate early aneurysm occlusion following WEB implantation and can be used to longitudinally monitor aneurysm healing progression.

Early Experience with Comaneci, a Newly FDA-Approved Controllable Assist Device for Wide-Necked Intracranial Aneurysm Coiling

BACKGROUND

Comaneci (Rapid Medical) is a compliant, adjustable mesh that provides temporary scaffolding during coiling of wide-necked intracranial aneurysms (WNAs) that preserves antegrade flow. We report our early multi-institutional experience with the Comaneci device in the USA.

METHOD

We reviewed all patients with WNAs that were treated using the Comaneci device for coil remodeling of ruptured and unruptured aneurysms at 4 institutions between July 2019 and May 2020. Clinical characteristics, angiographic variables, and endovascular results were assessed.

RESULTS

A total of 26 patients were included (18 women). The mean age was 62.7 years (range 44-81). Fifteen patients presented with ruptured aneurysms and 11 with unruptured aneurysms. The mean aneurysm neck width was 3.91 mm (range 1.9-6.5) with a mean dome-to-neck ratio of 1.57 (range 0.59-3.39). The mean maximum width was 5.80 mm (range 3.0-9.9) and the mean maximum height was 5.61 mm (range 2.0-11.8). Successful aneurysm occlusion was achieved in 25 of 26 patients. Complete occlusion was achieved in 16 patients, near-complete occlusion was observed in 9 patients, and 1 patient demonstrated residual filling. The mean time of device exposure was 24 min (range 8-76). No vasospasm was observed at the device location. Clot formation on the device was noted in 2 separate cases, but there were no clinical sequelae. There was 1 intraprocedural complication in a case that involved the simultaneous use of 2 Comaneci devices.

CONCLUSIONS

Our initial experience shows that the Comaneci device is a promising and reliable tool that can safely support coil remodeling of WNAs.

Perforator preservation technologies (PPT) based on a new neuro-interventional classification in endovascular treatment of perforator involving aneurysms (piANs)

BACKGROUND

Treatment of perforator involving aneurysm (piAN) remains a challenge to open and endovascular neurosurgeons. Our aim is to demonstrate a primary outcome of endovascular therapy for piANs with the use of perforator preservation technologies (PPT) based on a new neuro-interventional classification.

METHODS

The piANs were classified into type I: aneurysm really arises from perforating artery, type II: saccular aneurysm involves perforating arteries arising from its neck (IIa) or dome (IIb), and type III: fusiform aneurysm involves perforating artery. Stent protection technology of PPT was applied in type I and III aneurysms, and coil-basket protection technology in type II aneurysms. An immediate outcome of aneurysmal obliteration after treatment was evaluated (satisfactory obliteration: the saccular aneurysm body is densely embolized (I), leaving a gap in the neck (IIa) or dome (IIb) where the perforating artery arising; fusiform aneurysm is repaired and has a smooth inner wall), and successful perforating artery preservation was defined as keeping the good antegrade flow of those perforators on postoperative angiography. The periprocedural complication was closely monitored, and clinical and angiographic follow-ups were performed.

RESULTS

Six consecutive piANs (2 ruptured and 4 unruptured; 1 type I, 2 type IIa, 2 type IIb, and 1 type III) in 6 patients (aged from 43 to 66 years; 3 males) underwent endovascular therapy between November 2017 and July 2019. The immediate angiography after treatment showed 6 aneurysms obtained satisfactory obliteration, and all of their perforating arteries were successfully preserved. During clinical follow-up of 13-50 months, no ischemic or hemorrhagic event of the brain occurred in the 6 patients, but has one who developed ischemic event in the territory of involving perforators 4 h after operation and completely resolved within 24 h. Follow-up angiography at 3 to 10M showed patency of the parent artery and perforating arteries of treated aneurysms, with no aneurysmal recurrence.

CONCLUSIONS

Our perforator preservation technologies on the basis of the new neuro-interventional classification seem feasible, safe, and effective in protecting involved perforators while occluding aneurysm.

The evolution of intracranial aneurysm treatment techniques and future directions

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator’s experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Deformable motion compensation for interventional cone-beam CT

Image-guided therapies in the abdomen and pelvis are often hindered by motion artifacts in cone-beam CT (CBCT) arising from complex, non-periodic, deformable organ motion during long scan times (5-30 s). We propose a deformable image-based motion compensation method to address these challenges and improve CBCT guidance. Motion compensation is achieved by selecting a set of small regions of interest in the uncompensated image to minimize a cost function consisting of an autofocus objective and spatiotemporal regularization penalties. Motion trajectories are estimated using an iterative optimization algorithm (CMA-ES) and used to interpolate a 4D spatiotemporal motion vector field. The motion-compensated image is reconstructed using a modified filtered backprojection approach. Being image-based, the method does not require additional input besides the raw CBCT projection data and system geometry that are used for image reconstruction. Experimental studies investigated: (1) various autofocus objective functions, analyzed using a digital phantom with a range of sinusoidal motion magnitude (4, 8, 12, 16, 20 mm); (2) spatiotemporal regularization, studied using a CT dataset from The Cancer Imaging Archive with deformable sinusoidal motion of variable magnitude (10, 15, 20, 25 mm); and (3) performance in complex anatomy, evaluated in cadavers undergoing simple and complex motion imaged on a CBCT-capable mobile C-arm system (Cios Spin 3D, Siemens Healthineers, Forchheim, Germany). Gradient entropy was found to be the best autofocus objective for soft-tissue CBCT, increasing structural similarity (SSIM) by 42%-92% over the range of motion magnitudes investigated. The optimal temporal regularization strength was found to vary widely (0.5-5 mm^-2) over the range of motion magnitudes investigated, whereas optimal spatial regularization strength was relatively constant (0.1). In cadaver studies, deformable motion compensation was shown to improve local SSIM by ∼17% for simple motion and ∼21% for complex motion and provided strong visual improvement of motion artifacts (reduction of blurring and streaks and improved visibility of soft-tissue edges). The studies demonstrate the robustness of deformable motion compensation to a range of motion magnitudes, frequencies, and other factors (e.g. truncation and scatter).

Delayed cranial nerve palsy after successful coil embolization in cavernous sinus lesion

Cavernous sinus (CS) lesion is hard to access by surgical approach. With the development of endovascular technique, neurointerventional therapy is an alternative modality for CS lesions. This endovascular technique has been widely used for the past decade, avoiding the risks associated with surgical treatment. However, complications can still arise from coil embolization. Although immediate complication associate with embolic event or mass effect has been well described, but delayed (>1 year from treatment) nerve palsy after coil embolization is rare. We report two cases of delayed cranial nerve palsy after successful endovascular coil embolization in CS lesion.

Vascular Geometry Associated with Anterior Communicating Artery Aneurysm Formation

OBJECTIVE

To identify clinical and morphologic risk factors correlated with anterior communicating artery (ACoA) aneurysm formation.

METHODS

Three-dimensional morphologic parameters obtained from computed tomography angiography or digital subtraction angiography from 504 patients with ACoA aneurysms and 201 patients with aneurysms in other locations that were diagnosed at Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 were evaluated. The presence of hypoplastic and aplastic A1 segments and diameters and angles of surrounding parent and daughter vessels were examined. Univariable and multivariable statistical analyses were performed to determine statistical significance. Sensitivity analyses for small (≤3 mm) aneurysms only were also performed.

RESULTS

Aplastic and hypoplastic A1 segments were more common in the ACoA group (38.9% vs. 6.5% hypoplastic and 22.2% vs. 0.5% aplastic). In multivariable analysis, the presence of a hypoplastic A1 segment was associated with ACoA aneurysms. An A2-ACoA (daughter-daughter) angle was also significantly associated with ACoA aneurysms in multivariable analysis; however, as Pearson's correlation test between aneurysm width and daughter-daughter angle was significant, the daughter-daughter angle was most likely not independently associated with aneurysm presence, but rather might have been a result of the presence of an aneurysm. Subgroup analyses of small aneurysms (≤3 mm) and of unruptured aneurysms showed similar results.

CONCLUSIONS

Our results demonstrate that of all the morphologic parameters, the presence of a hypoplastic A1 segment was the only parameter independently associated with the presence of ACoA aneurysms that was not correlated with aneurysm size and could aid as a simple screening parameter.

In vivo comparison of braided (Accero) and laser-cut intracranial stents (Acclino, Credo): evaluation of vessel responses at subacute and mid-term follow-up in a rabbit model

This study aimed to investigate in vivo two stent technologies, with particular emphasis on thrombogenicity and inflammatory vessel remodeling processes. The micro-stents tested in this study were developed for intracranial aneurysm treatment. In our study twelve, New Zealand white rabbits were divided into two groups: 18 laser-cut stents (LCS) and 18 braided stents (BS) were impanated without admiration of antiplatelet medication. Three stents were implanted into each animal in the common carotid artery, subclavian artery, and abdominal aorta. Digital subtraction angiography was performed before and after stent implantation and at follow-up for the visualization of occurring In-stent thromboembolism or stenosis. The Stents were explanted for histopathological examination at two different timepoints, after 3 and 28 days. Angiographically neither in-stent thrombosis nor stenosis for both groups was seen. There was a progressive increase in the vessel diameter, which was more pronounced for BS than for LCS. We detected a higher number of thrombi adherent to the foreign material on day 3 for BS. On day 3, the neointima was absent, whereas the complete formation observed was on day 28. There was no significant difference between both groups regarding the thickness of the neointima. The in vivo model of our study enabled the evaluation of blood and vessel reactions for two different stent technologies. Differences in vessel dimension and tissue around the stents were observed on day 28. Histological analysis on day 3 enabled the assessment of thrombotic reactions, representing an important complementary result in long-term studies.

Endovascular coil embolization for unruptured intracranial aneurysms in patients over 80 years of age

Objective

As the average life span in modern society continues to increase, much interest is focused on high-risk procedures in elderly patients, including major surgical operations. We investigated the results of endovascular coiling of unruptured intracranial aneurysms (UIA) in patients over 80 years of age.

Methods

We retrospectively analyzed 39 patients aged over 80 years who underwent coil embolization for UIA between April 2007 and April 2019 at our hospital.

Results

Complete occlusion on digital subtraction angiography (DSA) immediately after surgery was performed in 44 (84.6%) of 52 cases of cerebral aneurysms. Four patients (7.7%) had residual aneurysmal necks, and four (7.7%) had contrast flow in the aneurysmal sac. Follow-up magnetic resonance angiography (mean: 8.2 months) was performed in 37 aneurysms in 24 patients. There was evidence of blood flow in the neck in seven cases (18.9%) and aneurysm in two cases (5.4%). Follow-up DSA (mean: 20.5 months) was performed in 14 aneurysms in 11 patients, and 11 aneurysms (78.6%) had complete occlusion, 1 aneurysm (7.1%) had an aneurysmal neck, and 2 aneurysms (14.3%) had contrast filling into the aneurysmal sac. Coil embolization procedure-related complications occurred in 3 patients (7.7%). Cerebral infarction occurred in 1 (2.6%), arterial dissection in 1 (2.6%), and hypoesthesia in 1 (2.6%).

Conclusions

Active treatment of UIA in elderly patients over 80 years of age through endovascular coil embolization can be considered.

Initial Raymond-Roy Occlusion Classification but not Packing Density Defines Risk for Recurrence after Aneurysm Coiling

Purpose

After coil embolization of intracranial aneurysms, it is currently not well understood whether the initial coil packing density or the type of aneurysm residual perfusion, depicted by the modified Raymond-Roy occlusion classification, primarily effects the rate of aneurysm recurrence. We hypothesized that these factors interact and only one remains an independent risk factor.

Methods

In this single center retrospective study, 440 patients with intracranial ruptured and unruptured aneurysms between 2010 and 2017 were screened. A total of 267 patients treated with stand-alone coiling, with or without stent or balloon assistance were included (age 54.1 ± 12.2 years, sex 70.4% female). Flow diverter or Woven EndoBridge (WEB) device implantation were exclusion criteria.

Results

Using a binary logistic regression model, independent risk factors for aneurysm recurrence were postinterventional modified Raymond-Roy occlusion classification class (Odds ratio [OR] 1.747, 95% confidence interval [CI] 1.231–2.480) and aneurysm diameter (OR 1.145, CI 1.032–1.271). A trend towards a higher recurrence in ruptured aneurysms did not reach significance (OR 1.656, CI 0.863–3.179). Aneurysm localization, packing density, and neck width were not independently associated with aneurysm recurrence.

Conclusion

Independent risk factors for aneurysm recurrence after coil embolization with and without stent or balloon assistance were aneurysm diameter and postinterventional grading within the modified Raymond-Roy occlusion classification. Packing density interacted with the latter and was not independently associated to recurrence.

Application of zero echo time MR angiography in follow-up of intracranial aneurysm remnant and in-stent lumen after embolization: a comparison study with digital subtraction angiography

Background

Intracranial aneurysm with endovascular treatment needs to be followed-up with a proper imaging method.

Purpose

To evaluate the performance of magnetic resonance angiography (MRA) with zero echo time at 1.5-T in assessing the intracranial aneurysm remnant and in-stent lumen as compared with time-of-flight MRA, with digital subtraction angiography as the gold standard.

Material and Methods

A total of 46 patients (17 men; mean age = 56.6±13.7 years) with 54 aneurysms who underwent coil embolization with or without stent were enrolled in this study. The presence of aneurysm remnant and the visualization of in-stent lumen were evaluated. The agreement of remnant identification between MRA with zero echo time and time-of-flight MRA with digital subtraction angiography was evaluated using Cohen’s kappa analysis. The performance of in-stent lumen visualization between MRA with zero echo time and time-of-flight MR angiography was compared with Chi-square test.

Results

Of 54 aneurysms, 27 were found to have remnants by digital subtraction angiography. The kappa value in identification of remnant of aneurysm was 0.852 between MRA with zero echo time and digital subtraction angiography and 0.741 between time-of-flight MRA and digital subtraction angiography. In detecting remnant of aneurysm, the sensitivity, specificity, positive predictive value, and negative predictive value were 96.3%, 88.9%, 89.7%, and 96.0% for MRA with zero echo time and 91.7%, 83.3%, 81.5%, and 92.6% for time-of-flight MRA, respectively. In visualizing in-stent lumen, MRA with zero echo time had better performance than time-of-flight MRA ( P < 0.001).

Conclusion

MR angiography with zero echo time might be a better non-invasive approach in assessing remnant of aneurysms and in-stent lumen as compared with time-of-flight MRA.

Clinical Safety and Effectiveness of Stent-Assisted Coil Embolization with Neuroform Atlas Stent in Intracranial Aneurysm

Objective

Stent-assisted coil embolization (SAC) is commonly used for treating wide-neck intracranial aneurysms. In this study, we aimed to assess the clinical safety and efficacy of the NeuroForm Atlas Stent during SAC of intracranial aneurysms.

Methods

We retrospectively analyzed data from patients with ruptured and unruptured cerebral aneurysms, who underwent SAC using the NeuroForm Atlas between February 2018 and July 2018. Favorable clinical outcomes and degree of aneurysm occlusion were defined as a modified Rankin scale score of ≤2 and a Raymond-Roy occlusion classification (RROC) class I/II during the immediate postoperative period and at the 6-month follow-up, respectively.

Results

Thirty-one consecutive patients with 33 cases, including 11 ruptured and 22 unruptured cases were treated via NeuroForm Atlas SAC. Among the 22 unruptured cases with 24 unruptured aneurysms had favorable clinical outcome. Complete occlusion (RROC I) was achieved in 16 aneurysms (66.7%), while neck remnants (RROC II) were observed in six aneurysms (25%). Among the 11 patients with ruptured aneurysms, two died due to re-bleeding and diabetic ketoacidosis. In ruptured cases, RROC I was observed in eight (72.7%) and RROC II was observed in three cases (27.3%). At the 6-month follow-up, no clinical events were observed in the 22 unruptured cases. In the ruptured nine cases, five patients recovered without neurologic deficits, while four experienced unfavorable outcomes at 6 months. Of the 29 aneurysms examined via angiography at the 6-month follow-up, 19 (65.5%) were RROC I, eight (27.6%) were RROC II and two (6.9%) were RROC III. There were no procedure-related hemorrhagic complications.

Conclusion

In this study, we found that stent-assisted coil embolization with NeuroForm Atlas stent may be safe and effective in the treatment of wide-neck intracranial aneurysms. NeuroForm Atlas SAC is feasible for the treatment of both ruptured and unruptured wide-neck aneurysms.

Histological and Transmission Electron Microscopy Results after Embolization with HydroSoft/HydroFrame Coils in Experimental Swine Aneurysm

Coiling and clipping are standard treatment strategies for cerebral aneurysms. Regardless of the strategy used, recanalization may affect the patient's prognosis. The aim of this study was to histologically and morphologically compare the tissue proliferation after coil embolization using bare platinum coils versus second-generation hydrogel coils (HydroSoft/HydroFrame; MicroVention, Inc., Aliso Viejo, CA, USA). Endothelial-like cell proliferation was seen in both groups at 2 weeks after surgery. Macroscopic findings showed a tighter layer at 4 weeks in the hydrogel coil group, and histological and immunohistochemical findings revealed endothelial cell proliferation. This layer became much thicker and tighter at 4 weeks after surgery. Aneurysms treated with second-generation hydrogel coils may be more stable and have a lower incidence of recanalization than those treated with bare platinum coils because of the tight endothelial layer proliferation.

Endovascular Treatment of Posterior Cerebral Artery Aneurysms With Flow Diversion: Case Series and Systematic Review

BACKGROUND

Flow diversion of posterior cerebral artery (PCA) aneurysms has not been widely reported, possibly owing to concerns regarding parent vessel size and branch vessel coverage.

OBJECTIVE

To examine the safety and effectiveness of PCA aneurysm flow diverter treatment.

METHODS

Retrospective review of PCA aneurysms treated with the Pipeline Embolization Device (PED; Medtronic Inc, Dublin, Ireland) at 3 neurovascular centers, including periprocedural complications and clinical and angiographic outcomes. Systematic review of the literature identified published reports of PCA aneurysms treated with flow diversion. Rates of aneurysm occlusion and complications were calculated, and outcomes of saccular and fusiform aneurysm treatments were compared.

RESULTS

Ten PCA aneurysms in 9 patients were treated with the PED. There were 2 intraprocedural thromboembolic events (20%), including 1 symptomatic infarction and 1 delayed PED thrombosis. Eight of 10 patients returned to or improved from their baseline functional status. Complete aneurysm occlusion with parent vessel preservation was achieved in 75% (6/8) of cases at mean follow-up of 16.7 mo. Eleven of 12 (92%) major branch vessels covered by a PED remained patent. Including the present study, systematic review of 15 studies found a complete aneurysm occlusion rate of 88% (30/34) and complication rate of 26% (10/38), including 5 symptomatic ischemic strokes (13%; 5/38). Fusiform aneurysms more frequently completely occluded compared with saccular aneurysms (100% vs 70%; P = .03) but were associated with a higher complication rate (43% vs 9%; P = .06).

CONCLUSION

The safety and effectiveness profile of flow diverter treatment of PCA aneurysms may be acceptable in select cases.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

An electrospun fiber-covered stent with programmable dual drug release for endothelialization acceleration and lumen stenosis prevention

Aneurysmal subarachnoid hemorrhage (SAH) causes high rates of mortality and morbidity. A covered stent is an effective endovascular treatment for complicated aneurysms intractable to endovascular coiling and surgical clipping. However, in-stent restenosis and delayed endothelialization are the main challenges contributing to its safety. In this study, we designed a biofunctional stent covered with dual drug-loaded electrospun fibers to achieve programmed vascular endothelial growth factor (VEGF) and paclitaxel (PTX) release for the early promotion of stent endothelialization and long-term inhibition of stenosis caused by smooth muscle hyperplasia. By encapsulating PTX-loaded mesoporous silica nanoparticles (MSNs) within electrospun polylactic acid (PLA) fibers, the release period of PTX was effectively extended. Furthermore, VEGF was conjugated onto the surface of the membrane by reacting with polydopamine (PDA) for quick release. The in vitro drug release profile revealed the sustained release of PTX, which persisted for 63 days without early burst release, while up to 87.05% of VEGF was rapidly released within 3 days. After 6 days of incubation, cell experiments demonstrated that the dual drug-loaded scaffold effectively prompted endothelial cell proliferation (488% vs. 386% in the control group, P = 0.001) and inhibited the proliferation of smooth muscle cells (SMCs) using the 21-day extracts (155% vs. 303% in the control group, P = 0.039). Animal studies showed that compared to bare stents, the drug-loaded covered stents improved the immediate- and mid-term complete aneurysm occlusion rates (P < 0.05). The drug-loaded covered stents also showed earlier endothelialization promotion and better lumen restenosis than normal covered stents (0% vs. 25%, P = 0.29) for 12 weeks. Overall, a programmed dual drug-loaded scaffold that effectively occluded the aneurysm sac was developed in this study, and the discrete release of VEGF and PTX promoted endothelialization and prevented in-stent stenosis. This study provided a new method to improve the biosafety of implanted covered stents for the treatment of intracranial aneurysms. STATEMENT OF SIGNIFICANCE: Aneurysmal subarachnoid hemorrhage (SAH) is one of the most common hemorrhage stroke resulted in a nearly 40% mortality and 33% morbidity due to sudden rupture of an intracranial aneurysm. Endovascular coil embolism is a popular treatment for aneurysm but this technique run high risk of bleeding, mass effect, low complete occlusion rate and higher recanalization rate due to its operation conducted within aneurysm sac. A bio-functional membrane knitted by dual-drug loaded electrospun fibers covered on a stent was designed to realize programed vascular endothelial growth factor and paclitaxel release for the early promotion of vascular endothelium and long-term inhibition of stenosis caused by smooth muscle hyperplasia. This study provides new method to improve the biosafety of covered stent insertion for the treatment of intracranial aneurysms.

Evaluation of a modular in vitro neurovascular procedure simulation for intracranial aneurysm embolization

BACKGROUND

Rapid development in endovascular aneurysm therapy continuously drives demand for suitable neurointerventional training opportunities.

OBJECTIVE

To investigate the value of an integrated modular neurovascular training environment for aneurysm embolization using additively manufactured vascular models.

METHODS

A large portfolio of 30 patient-specific aneurysm models derived from different treatment settings (eg, coiling, flow diversion, flow disruption) was fabricated using additive manufacturing. Models were integrated into a customizable neurointerventional simulator with interchangeable intracranial and cervical vessel segments and physiological circuit conditions ('HANNES'; Hamburg ANatomic Neurointerventional Endovascular Simulator). Multiple training courses were performed and participant feedback was obtained using a questionnaire.

RESULTS

Training for aneurysm embolization could be reliably performed using HANNES. Case-specific clinical difficulties, such as difficult aneurysm access or coil dislocation, could be reproduced. During a training session, models could be easily exchanged owing to standardized connectors in order to switch to a different treatment situation or to change from 'treated' back to 'untreated' condition. Among 23 participants evaluating hands-on courses using a five-point scale from 1 (strongly agree) to 5 (strongly disagree), HANNES was mostly rated as 'highly suitable for practicing aneurysm coil embolization' (1.78±0.79).

CONCLUSION

HANNES offers a wide variability and flexibility for case-specific hands-on training of intracranial aneurysm treatment, providing equal training conditions for each situation. The high degree of standardization offered may be valuable for analysis of device behavior or assessment of physician skills. Moreover, it has the ability to reduce the need for animal experiments.

Endovascular Treatments Performed Collaboratively by the Society of Korean Endovascular Neurosurgeons Members : A Nationwide Multicenter Survey

Objective

Since less invasive endovascular treatment was introduced to South Korea in 1994, a considerable proportion of endovascular treatments have been performed by neuroradiology doctors, and endovascular treatments by vascular neurosurgeons have recently increased. However, few specific statistics are known regarding how many endovascular treatments are performed by neurosurgeons. Thus, authors compared endovascular treatments collaboratively performed by vascular neurosurgeons with all cases throughout South Korea from 2013 to 2017 to elucidate the role of neurosurgeons in the field of endovascular treatment in South Korea.

Methods

The Society of Korean Endovascular Neurosurgeons (SKEN) has issued annual reports every year since 2014. These reports cover statistics on endovascular treatments collaboratively or individually performed by SKEN members from 2013 to 2017. The data was requested and collected from vascular neurosurgeons in various hospitals. The study involved 77 hospitals in its first year, and 100 in its last. National statistics on endovascular treatment from all over South Korea were obtained from the Healthcare Bigdata Hub website of the Health Insurance Review & Assessment Service based on the Electronic Data Interchange (EDI) codes (in the case of intra-arterial (IA) thrombolysis, however, statistics were based on a combination of the EDI and I63 codes, a cerebral infarction disease code) from 2013 to 2017. These two data sets were directly compared and the ratios were obtained.

Results

Regionally, during the entire study period, endovascular treatments by SKEN members were most common in Gyeonggi-do, followed by Seoul and Busan. Among the endovascular treatments, conventional cerebral angiography was the most common, followed by cerebral aneurysmal coiling, endovascular treatments for ischemic stroke, and finally endovascular treatments for vascular malformation and tumor embolization. The number of endovascular treatments performed by SKEN members increased every year.

Conclusion

The SKEN members have been responsible for the major role of endovascular treatments in South Korea for the recent 5 years. This was achieved through the perseverance of senior members who started out in the midst of hardship, the establishment of standards for the training/certification of endovascular neurosurgery, and the enthusiasm of current SKEN members who followed. To provide better treatment to patients, we will have to make further progress in SKEN.

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

Background

Flow-diverting stents (FDS) have revolutionized the endovascular management of unruptured, complex, wide-necked, and giant aneurysms. There is no consensus on management of complications associated with the placement of these devices. This review focuses on the management of complications of FDS for the treatment of intracranial aneurysms.

Summary

We performed a systematic, qualitative review using electronic databases MEDLINE and Google Scholar. Complications of FDS placement generally occur during the perioperative period.

Key Message

Complications associated with FDS may be divided into periprocedural complications, immediate postprocedural complications, and delayed complications. We sought to review these complications and novel management strategies that have been reported in the literature.

Favorable Outcome of Endovascular Treatment for Intracranial Aneurysms: A Single-Center Study in Thailand

Purpose:

The purpose of this study is to collect the information on patients with intracranial aneurysm (IA) receiving endovascular management in Siriraj Hospital, Mahidol University, Thailand.

Materials and Methods:

We retrospectively reviewed data from patients with IA who underwent endovascular treatment from January 1997 through July 2013. We collected patients’ demographic data including age, sex, clinical presentations, and aneurysmal profiles, as well as endovascular treatment technique, complications, angiographic results, and regrowth rate. Treatment results included success rate, clinical findings during follow-up, and regrowth rate.

Results:

We reviewed data from 497 patients with 636 aneurysms (female:male ratio, 1.9:1; age range, 15–90 years; mean age, 59.18 years) and 69% presented with rupture. One hundred and twenty patients with 127 aneurysms received endovascular treatment. The most common location for endovascular treatment was the posterior communicating artery (15.8%), and endovascular techniques were used most often for posterior circulation and paraclinoid aneurysms. The success rate was approximately 99.2% with a 16.5% regrowth rate and no rebleeding. Regrowth rate did not correlate with immediate postoperative angiographic findings. We encountered 23 complications (18.1%); most commonly, intra-procedural rupture (7/23). Good outcomes occurred in approximately 95.9% of the patients.

Conclusions:

The success rate for endovascular treatment was >90%. Regrowth rate and clinical outcomes were within standard limits. Posterior circulation and paraclinoid aneurysms were our main targets. We tended to use fewer devices and simpler techniques to secure ruptured IA; however, the regrowth rate was similar to that using device-assisted techniques in other studies. We found no significant factors affecting regrowth rate, including immediate posttreatment angiographic results.

The Neuroform Atlas stent to assist coil embolization of intracranial aneurysms: a multicentre experience

Objective

To assess the clinical safety and efficacy of the Atlas microstent in stent-assisted coil embolization of wide-necked intracranial aneurysms.

Methods

Single-center observational study in 36 patients (24 female, 12 male, mean age 56 years) with 37 aneurysms for the endovascular treatment of wide-necked aneurysms. After giving informed consent, patients were included according to the following criteria: aneurysm dome-to-neck ratio <2 or neck diameter >4 mm, and a parent vessel diameter of ≤4.5 mm. Primary endpoint for clinical safety was absence of death, absence of major or minor stroke, and absence of transient ischemic attack. Primary endpoint for treatment efficacy was complete angiographic occlusion according to the Raymond-Roy occlusion classification (RROC) immediately after the procedure.

Results

In 36/37 (97%) cases, the primary endpoint of safety was reached, one patient had a transitory ischemic attack which completely resolved until discharge. In 31/37 (84%) cases, complete occlusion (RROC 1) was reached, and in 6/36 (17%), a residual neck remained (RROC 2). A sequential approach (first stent, then coiling through the same catheter) was used in 21 cases; the other 16 were treated with the jailing technique. Deployment was technically successful in all cases. Follow-up at a median of 6.1 months was available for 29/37 (78%) aneurysms and showed complete occlusion in 27/29 aneurysms (93%) and a neck remnant in 2 cases (7%).

Conclusion

Deployment of the Neuroform Atlas microstent is a safe and effective method for the treatment of intracranial wide-necked aneurysms.

Rescue Therapy for Procedural Complications Associated With Deployment of Flow-Diverting Devices in Cerebral Aneurysms

Flow diverting devices (FDDs) have revolutionized the treatment of morphologically complex intracranial aneurysms such as wide-necked, giant, or fusiform aneurysms. Although FDDs are extremely effective, they carry a small yet significant risk of intraprocedural complications. As the implementation of these devices increases, the ability to predict and rapidly treat complications, especially those that are iatrogenic or intraprocedural in nature, is becoming increasingly more necessary.

Our objective in this paper is to provide a descriptive summary of the various types of intraprocedural complications that may occur during FDDs deployment and how they may best be treated. A systematic and qualitative review of the literature was conducted using electronic databases MEDLINE and Google Scholar. Searches consisted of Boolean operators “AND” and “OR” for the following terms in different combinations: “aneurysm,” “endovascular,” “flow diverter,” “intracranial,” and “pipeline.”

A total of 94 papers were included in our analysis; approximately 87 of these papers dealt with periprocedural endovascular (mainly related to FDDs) complications and their treatment; 7 studies concerned background material. The main categories of periprocedural complications encountered during deployment of FDDs are failure of occlusion, parent vessel injury and/or rupture, spontaneous intraparenchymal hemorrhage, migration or malposition of the FDDs, thromboembolic or ischemic events, and side branch occlusion

Periprocedural complications occur mainly due to thromboembolic events or mechanical issues related to device deployment and placement. With increasing use and expanding versatility of FDDs, the understanding of these complications is vital in order to effectively manage such situations in a timely manner.

Korean Clinical Practice Guidelines for Aneurysmal Subarachnoid Hemorrhage

Despite advancements in treating ruptured cerebral aneurysms, an aneurysmal subarachnoid hemorrhage (aSAH) is still a grave cerebrovascular disease associated with a high rate of morbidity and mortality. Based on the literature published to date, worldwide academic and governmental committees have developed clinical practice guidelines (CPGs) to propose standards for disease management in order to achieve the best treatment outcomes for aSAHs. In 2013, the Korean Society of Cerebrovascular Surgeons issued a Korean version of the CPGs for aSAHs. The group researched all articles and major foreign CPGs published in English until December 2015 using several search engines. Based on these articles, levels of evidence and grades of recommendations were determined by our society as well as by other related Quality Control Committees from neurointervention, neurology and rehabilitation medicine. The Korean version of the CPGs for aSAHs includes risk factors, diagnosis, initial management, medical and surgical management to prevent rebleeding, management of delayed cerebral ischemia and vasospasm, treatment of hydrocephalus, treatment of medical complications and early rehabilitation. The CPGs are not the absolute standard but are the present reference as the evidence is still incomplete, each environment of clinical practice is different, and there is a high probability of variation in the current recommendations. The CPGs will be useful in the fields of clinical practice and research.

An injectable shear-thinning biomaterial for endovascular embolization

Improved endovascular embolization of vascular conditions can generate better patient outcomes and minimize the need for repeat procedures. However, many embolic materials, such as metallic coils or liquid embolic agents, are associated with limitations and complications such as breakthrough bleeding, coil migration, coil compaction, recanalization, adhesion of the catheter to the embolic agent, or toxicity. Here, we engineered a shear-thinning biomaterial (STB), a nanocomposite hydrogel containing gelatin and silicate nanoplatelets, to function as an embolic agent for endovascular embolization procedures. STBs are injectable through clinical catheters and needles and have hemostatic activity comparable to metallic coils, the current gold standard. In addition, STBs withstand physiological pressures without fragmentation or displacement in elastomeric channels in vitro and in explant vessels ex vivo. In vitro experiments also indicated that STB embolization did not rely on intrinsic thrombosis as coils did for occlusion, suggesting that the biomaterial may be suitable for use in patients on anticoagulation therapy or those with coagulopathy. Using computed tomography imaging, the biomaterial was shown to fully occlude murine and porcine vasculature in vivo and remain at the site of injection without fragmentation or nontarget embolization. Given the advantages of rapid delivery, in vivo stability, and independent occlusion that does not rely on intrinsic thrombosis, STBs offer an alternative gel-based embolic agent with translational potential for endovascular embolization.

Procedure-related Complications during Endovascular Treatment of Intracranial Saccular Aneurysms

Objective

We evaluate the rates and outcomes of major procedure-related complications during coiling.

Materials and Methods

Between 2007 and 2015, 436 intracranial saccular aneurysms were treated. Complications are categorized as three types: intraprocedural aneurysm rupture (IAR), thromboembolism (TE), and post-procedural early rebleeding (PER). And we evaluated the risk factors of procedure related complications by multivariate analysis.

Results

Complications occurred in 61 aneurysms (14%). The overall incidence of complications in subarachnoid hemorrhage (SAH) was significantly higher than in unruptured intracranial aneurysm (UIA) (20% vs. 6%). The incidence of IAR and TE were higher in SAH than in UIA (IAR 12% vs. 4%, TE 7% vs. 3%, p < 0.05). Five PER occurred only in SAH. In 34 UIA which were treated with balloon-assisted coiling (BAC), all these patients had good recovery despite 3 patients had the IAR. The incidence of IAR and TE were not different between BAC and non-BAC groups (p > 0.05). All 7 patients who had IAR during BAC had good recovery. In multiple logistic regression analysis, female gender, SAH, and intraventricular hemorrhage were associated with procedure related complication (p < 0.05).

Conclusion

Endovascular coil embolization is a minimally invasive procedure, but incidence of its complication is not low, especially in SAH. BAC can be a good tool to avoid poor outcome from unexpected IAR during coiling. While IA tirofiban injection is a useful therapy in TE during coiling, sometimes we are aware of the risk of the early rebleeding in SAH patients.

Diagnosis and treatment of pericallosal artery aneurysms

OBJECTIVE

Pericallosal artery aneurysms are not common clinically. The microsurgery and endovascular therapy are surgically challenging operations. The objective of the study is to summarize their clinical symptoms and optimal treatment strategies of pericallosal artery aneurysms.

METHODS

Nine cases of pericallosal artery aneurysms detected by digital subtraction angiography (DSA) were reviewed. The clinical manifestation, brain imaging characteristics, and optimal treatment methods were summarized.

RESULTS

Patients with spontaneous aneurysm had good clinical outcomes after endovascular coiling or microsurgical clipping treatment. There were no any neurological function deficits in five patients. One patient suffered from permanent neurological function deficits. Patients with traumatic aneurysm pericallosal had relatively poor outcomes, including two patients showing disturbed consciousness and the paralysis of the lower limbs with slow recovery, and one patient was dead after the surgery.

CONCLUSION

Spontaneous subarachnoid hemorrhage and interhemispheric fissure hematoma suggest spontaneously pericallosal aneurysm, while traumatic corpus callosum hematoma as well the accompanying embryo of intraventricular hemorrhage suggest traumatic pericallosal aneurysm. Endovascular embolization is the primary surgical treatment for pericallosal aneurysm, while patients with pericallosal aneurysm are not suitable for surgical treatment. Microsurgical clipping treatment may be a choice. However, both of these treatment strategies have high risk.

MR Coagulation: A Novel Minimally Invasive Approach to Aneurysm Repair

PURPOSE

To demonstrate a proof of concept of magnetic resonance (MR) coagulation, in which MR imaging scanner-induced radiofrequency (RF) heating at the end of an intracatheter long wire heats and coagulates a protein solution to effect a vascular repair by embolization.

MATERIALS AND METHODS

MR coagulation was simulated by finite-element modeling of electromagnetic fields and specific absorption rate (SAR) in a phantom. A glass phantom consisting of a spherical cavity joined to the side of a tube was incorporated into a flow system to simulate an aneurysm and flowing blood with velocities of 0-1.7 mL/s. A double-lumen catheter containing the wire and fiberoptic temperature sensor in 1 lumen was passed through the flow system into the aneurysm, and 9 cm³ of protein solution was injected into the aneurysm through the second lumen. The distal end of the wire was laid on the patient table as an antenna to couple RF from the body coil or was connected to a separate tuned RF pickup coil. A high RF duty-cycle turbo spin-echo pulse sequence excited the wire such that RF energy deposited at the tip of the wire coagulated the protein solution, embolizing the aneurysm.

RESULTS

The protein coagulation temperature of 60°C was reached in the aneurysm in ∼12 seconds, yielding a coagulated mass that largely filled the aneurysm. The heating rate was controlled by adjusting pulse-sequence parameters.

CONCLUSIONS

MR coagulation has the potential to embolize vascular defects by coagulating a protein solution delivered by catheter using MR imaging scanner-induced RF heating of an intracatheter wire.

The minipterional approach for ruptured and unruptured anterior circulation aneurysms: Our initial experience

Objective:

To report our experience with the minipterional (MPT) craniotomy approach for anterior circulation aneurysms and to discuss the clinical outcomes as well as to evaluate the advantages of this unique approach.

Materials and Methods:

Single-center retrospective review of 57 cases involving anterior circulation aneurysms both ruptured and unruptured aneurysms treated with the MPT. We analyzed the clinical and patient demographic data, aneurysm characteristics, surgical outcomes, and complications in these individuals.

Results:

Between July 2008 and March 2014, of the 57 patients reviewed: 45 had middle cerebral artery (MCA), 6 had internal carotid artery terminus, and 7 had posterior communicating artery aneurysms. 20 of the 57 patients presented with a ruptured aneurysm. The average aneurysm size was 5.8 mm. The length of hospitalization for unruptured aneurysm cases ranged between 3 and 5 days. The average follow-up for all cases was 21.5 months. Successful clipping of the aneurysms was obtained in all patients. None of the cases required additional skin incisions or craniotomy extensions. The overall surgical outcomes were favorable. There was no postoperative facial nerve damage, temporalis muscle wasting, or symptoms of paresthesias around the incision line. Two patients developed a postoperative stroke manifested as symptoms of unilateral arm and facial weakness, receptive aphasia, and dysarthria.

Conclusion:

The MPT provides a reliable and less invasive alternative to the standard pterional craniotomy. Furthermore, ruptured and unruptured anterior circulation aneurysms can safely and effectively be treated with limited bone removal which provides better cosmetic outcomes and excellent postoperative temporalis muscle function.

Complication Risk Factors in Anterior Choroidal Artery Aneurysm Treatment

OBJECT

The anterior choroidal artery (AChoA) is a rare location for intracranial aneurysms. The treatment of these aneurysms may be challenging due to the risk of occlusion of such a small and eloquent artery as the AChoA. We aimed to evaluate the risk factors for complications in AChoA aneurysm treatment.

METHODS

We retrospectively analyzed 47 consecutive AChoA aneurysms in 40 patients treated in our institution from 1999 and 2014 by endovascular means (87%) or surgical clipping (13%). Minor (transient or minor neurological deficits) and major complications (severe permanent neurological deficits or death) were systematically recorded. The influence of patient age, sex, aneurysm size, neck size, shape, dome-to-neck ratio and treatment technique on the occurrence of procedure-related complications was evaluated.

RESULTS

Of the patients 11 experienced procedure-related complications (5 major, 6 minor). Aneurysms with multilobed shape were significantly associated with a higher procedure-related complication rate. There was a tendency for higher major procedure-related complication rate in small volume aneurysms. We did not find any association between the other factors analyzed and occurrence of procedure-related complications.

CONCLUSION

Treatment of AChoA aneurysms has an acceptable complication risk. We did not find any significant differences between surgical and endovascular treatment in terms of procedure-related complication rates. Multilobed aneurysms were significantly associated with a higher procedure-related complication rate.

Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a neurological emergency with high risk of neurological decline and death. Although the presentation of a thunderclap headache or the worst headache of a patient's life easily triggers the evaluation for SAH, subtle presentations are still missed. The gold standard for diagnostic evaluation of SAH remains noncontrast head computed tomography (CT) followed by lumbar puncture if the CT is negative for SAH. Management of patients with SAH follows standard resuscitation of critically ill patients with the emphasis on reducing risks of rebleeding and avoiding secondary brain injuries.

Optimal first coil selection to avoid aneurysmal recanalization in endovascular intracranial aneurysmal coiling

BACKGROUND

Aneurysmal recanalization is a problem with endovascular coiling and one of its risk factors is the low volume embolization ratio (VER). The first coil VER (1st VER) is believed to be critical for obtaining a high VER. The main objective of this study was to evaluate factors potentially useful for selecting the optimal 1st VER for endovascular coiling.

METHODS

609 initial saccular aneurysmal treatments performed between January 2010 and December 2014 at our institution were included in this retrospective study. Attempted procedures, retreatment cases, intraoperative rupture cases, and stent-assisted coiling cases were excluded. Age, sex, aneurysm location, ruptured aneurysm, aneurysm shape, neck size, maximum aneurysm size, dome-to-neck ratio, aneurysm volume, procedure, immediate Raymond scale score, 1st VER, and VER between the recanalization groups and non-recanalization groups were compared.

RESULTS

The factors related to recanalization were ruptured aneurysms, neck width, maximum aneurysm size, aneurysm volume, procedure, 1st VER, and VER. The cut-off values for aneurysm recanalization were a 1st VER of 10.0% and a VER of 33.0%. The maximum average VER of normal size aneurysms was found in the groups with a 1st VER of 17.5-20.0%.

CONCLUSIONS

1st VER was found to be a helpful index for estimating aneurysmal recanalization after coil embolization. The target 1st VER was 17.5-20.0% for obtaining a higher VER and avoiding recanalization.

Application of actuator-driven pulsed water jet in aneurysmal subarachnoid hemorrhage surgery: its effectiveness for dissection around ruptured aneurysmal walls and subarachnoid clot removal

In clipping surgery for aneurysmal subarachnoid hemorrhage (aSAH), critical steps include clot removal and dissection of aneurysms without premature rupture or brain injuries. To pursue this goal, a piezo actuator-driven pulsed water jet (ADPJ) system was introduced in this study. This study included 42 patients, who suffered aSAH and underwent clipping surgery. Eleven patients underwent surgery with the assistance of the ADPJ system (ADPJ group). In the other 31 patients, surgery was performed without the ADPJ system (Control group). The ADPJ system was used for clot removal and aneurysmal dissection. The clinical impact of the ADPJ system was judged by comparing the rate of premature rupture, degree of clot removal, and clinical outcomes. Intraoperatively, a premature rupture was encountered in 18.2 and 25.8% of cases in the ADPJ and control groups, respectively. Although the differences were not statistically significant, intraoperative observation suggested that the ADPJ system was effective in clot removal and dissection of aneurysms in a safe manner. Computed tomography scans indicated the achievement of higher degrees of clot removal, especially when the ADPJ system was used for cases with preoperative clot volumes of more than 25 ml (p = 0.047, Mann-Whitney U test). Clinical outcomes, including incidence of postoperative brain injury or symptomatic vasospasm, were similar in both groups. We described our preliminary surgical results using the ADPJ system for aSAH. Although further study is needed, the ADPJ system was considered a safe and effective tool for clot removal and dissection of aneurysms.

Update on Endovascular Treatment of Cerebrovascular Diseases

Several developments in endovascular technology have greatly expanded the application of these techniques to treat extra- and intracranial cerebrovascular diseases. This review explores the indications, techniques, and clinical results for endovascular treatment of ischemic stroke and intracranial stenoses, aneurysms, and arteriovenous malformations.

Endovascular Treatment of Intracranial Aneurysms: Long-Term Follow-up

Endovascular treatment of intracranial aneurysms is increasingly used and has evolved as an alternative to surgical clipping. However, its long-term efficacy has yet to be established. This retrospective hospital based (tertiary teaching hospital) study aimed to identify factors that might be important in predicting initial efficacy of this treatment and a long-term follow-up to study the clinical and angiographic results of treated aneurysms. A total of 80 aneurysms in 78 patients were treated and analyzed, and the percentage of occlusion calculated. Overall, 51/80 (64 %) cases were treated with selective endovascular coil occlusion and 29/80 (36 %) by parent artery occlusion. The shape of the aneurysm rest was noted on the immediate post treatment and follow-up angiograms. Immediate and follow-up clinical status was also noted using the Glasgow outcome scale. The clinical and radiological changes on follow-up were assessed and possible factors involved were analyzed. Of the 50 patients of intracranial aneurysms that underwent selective aneurysm coiling, good immediate outcome (Glasgow outcome scale 1 and 2) was seen in 36/50 (72 %) cases. Narrow necked aneurysms showed a good immediate result (90–100 % packing) in all cases 28/28 (100 %). Amongst the wide necked aneurysms, good packing (90–100 %) was achieved in 17/23 (73 %) cases. Amongst the cases treated with parent artery occlusion, complete occlusion was noted in 20/29 (69 %) cases. No subarachnoid hemorrhage was seen in any of the followed up cases of coiled aneurysms. A statistically significant relationship was noted between aneurysm neck size and immediate angiographic outcome. Long-term angiographic recurrences were found more often in large aneurysms. Endovascular treatment of intracranial aneurysms is a safe and effective treatment modality that offers protection from recurrent subarachnoid hemorrhage.

Treatment of Intracranial Aneurysms: Clipping Versus Coiling

Intracranial aneurysms (IAs) have an estimated incidence of up to 10 % and can lead to serious morbidity and mortality. Because of this, the natural history of IAs has been studied extensively, with rupture rates ranging from 0.5 to 7 %, depending on aneurysm characteristics. The spectrum of presentation of IAs ranges from incidental detection to devastating subarachnoid hemorrhage. Although the gold standard imaging technique is intra-arterial digital subtraction angiography, other modalities such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are being increasingly used for screening and treatment planning. Management of these patients depends upon a number of factors including aneurysmal, patient, institutional, and operator factors. The ultimate goal of treating patients with IAs is complete and permanent occlusion of the aneurysm sac in order to eliminate future hemorrhagic risk, while preserving or restoring the patient's neurological function. The most common treatment approaches include microsurgical clipping and endovascular coiling, and multiple studies have compared these two techniques. To date, three large prospective, randomized studies have been done: a study from Finland, International Subarachnoid Aneurysm Trial (ISAT), and the Barrow Ruptured Aneurysm Trial (BRAT). Despite differences in methodology, the results were similar: in patients undergoing coiling, although rates of rebleeding and retreatment are higher, the overall rate of poor outcomes at 12 months was significantly lower. As minimally invasive procedures and devices continue to be refined, endovascular strategies are likely to increase in popularity. However, as long-term outcome studies become available, it is increasingly apparent that they are complementary treatment strategies, with patient selection of critical importance.

Optimum coil insertion speed of various coils in brain aneurysm embolization in vitro

A coil must comprise material with shape memory to perform optimal coil embolization. To achieve this, the alloy characteristics of the coil (hardness, shape, and thickness) must be understood. In this experiment, a catheter was fixed in the bright position and the movement of the coil was observed under a constant rate of insertion; the optimal insertion rate during clinical use was investigated. The first coil insertion speed was evaluated using simulated aneurysms in an in vivo arterial model. The results showed that the insertion force relates to the deployment shape of the coil, that the feedback through the force indicator using sound is very effective, and that the recorder is useful for analysis of coil embolization. The inserted coils during aneurysm embolization were able to wind uniformly within the aneurysm due to a variety of factors (guiding or micro-catheter position and kick-back phenomenon such as delivery wire). Optimal speed is achieved with proper coil design, which allows the coil to be inserted into the aneurysm. The shape and size of the aneurysm can help determine the necessary size and design of the coil that should be used during the optimal speed range. Aneurysm wall and coil characteristics are considered, along with the friction state of the coil (hardness, shape, and thickness), leading to improvements in safety during the insertion procedure at optimum speed.

Early outcomes and perioperative complications of endovascular embolization in patients with aneurysmal SAH

BACKGROUND

We still lack reliable data on the outcomes of endovascular coiling for ruptured cerebral aneurysms. As this is still an evolving technique, the outcomes of the procedures performed in the past and more recently cannot be directly compared. We present the early outcomes of endovascular coiling in a relatively large group of patients with ruptured intracranial aneurysms.

METHOD

The study included 190 consecutive patients (a total of 216 aneurysms) subjected to endovascular coiling in 2006-2013 (127 women aged 56±13 years and 63 men aged 50± 15 years). Up to 87.5% of the aneurysms were located within anterior circulation. Most patients presented with "mild to moderate" subarachnoid hemorrhages (85% of Hunt &Hess scores 1-3, and 72% of Fisher scores 1-3).

RESULTS

Embolization was feasible in 176 (92.6%) patients. In 14 cases, the embolization was not attainable due to unfavorable anatomy of the aneurysm, intraoperative vasospasm and/or aneurysm rupture, or prolapse of a coil. Early complications related to the procedure were recorded in 23 (13.1%) patients. The most common perioperative complication was aneurysm rupture. All fatal complications occurred in patients with aneurysms located at the anterior circle of Willis. At the time of discharge, 126 patients scored 4 or 5 on the Glasgow Outcome Scale.

CONCLUSIONS

Endovascular embolization is an effective and relatively safe method for treatment of ruptured cerebral aneurysms. Complications related to the procedure are significantly less frequent in the case of vertebral-basilar complex aneurysms.