Embolization of intracranial aneurysms with HydroSoft coils: results of the Korean multicenter study

Single Component Polymers, Polymer Blends, and Polymer Composites for Interventional Endovascular Embolization of Intracranial Aneurysms

Intracranial aneurysm is the abnormal focal dilation in brain arteries. When untreated, it can enlarge to rupture points and account for subarachnoid hemorrhage cases. Intracranial aneurysms can be treated by blocking the flow of blood to the aneurysm sac with clipping of the aneurysm neck or endovascular embolization with embolics to promote the formation of the thrombus. Coils or an embolic device are inserted endovascularly into the aneurysm via a micro-catheter to fill the aneurysm. Many embolization materials have been developed. An embolization coil made of soft and thin platinum wire called the "Guglielmi detachable coil" (GDC) enables safer treatment for brain aneurysms. However, patients may experience aneurysm recurrence because of incomplete coil filling or compaction over time. Unsatisfactory recanalization rates and incomplete occlusion are the drawbacks of endovascular embolization. So, the fabrication of new medical devices with less invasive surgical techniques is mandatory to enhance the long-term therapeutic performance of existing endovascular procedures. For this aim, the current article reviews polymeric materials including blends and composites employed for embolization of intracranial aneurysms. Polymeric materials used in embolic agents, their advantages and challenges, results of the strategies used to overcome treatment, and results of clinical experiences are summarized and discussed.

Comparison between second generation HydroSoft coils and bare platinum coils for the treatment of large intracranial aneurysms

BACKGROUND

The development of HydroSoft coils (HSC) aims to reduce the high recurrence and retreatment rates observed in large brain aneurysms by improving primary brain aneurysm filling and thus occlusion efficacy. We compared clinical and angiographic effectiveness of bare platinum coils (BPC) versus second generation HSC for large intracranial aneurysms at our center.

METHODS

We included 61 large aneurysms between 2015 and 2018, 29 embolized primarily using HSC and 32 treated with BPC. The aneurysm occlusion rates were assessed after 3 and 12 months with an MRI scan and at 6 moths with a control digital subtraction angiography (DSA) using the Raymond-Roy occlusion classification (RROC). Clinical outcomes were evaluated using the modified ranking scale (mRS).

RESULTS

The observed immediate occlusion rate was slightly better in the BPC group, however, this group had a significant increase of progressive reperfusion at all imaging follow-up. Contrarily, the rate of complete occlusion increased significantly in the HSC group, starting from the 6 and 12-months follow-up. 7 aneurysms (11.4%) were re-treated (15.6% BPC and 6.9% HSC). The 6 and 12-months clinical data showed mRS score 0-1 in 96.7% of patients.

CONCLUSIONS

In our single-center experience, the second generation HydroSoft coils were shown to be safe and effective for endovascular treatment of large intracranial aneurysms with encouraging clinical and angiographic results, also for ruptured aneurysms. Even if the validity is limited due to our small cohort size, HSC showed a significantly lower rate of recurrence at mid-term follow-up when compared to BPC.

Eosinophilic meningitis following suboccipital craniotomy without bovine dural graft: illustrative case

BACKGROUND

Eosinophilic meningitis is a rare known complication after brain surgery associated with duraplasty using artificial bovine graft. However, eosinophilic meningitis after craniotomy without bovine dural graft has not been reported.

OBSERVATIONS

A 48-year-old female presented with lateral medullary infarction caused by a vertebral artery dissecting aneurysm incorporating the posterior inferior cerebellar artery (PICA). The authors performed occipital artery–PICA anastomosis and repaired the dura by primary suture without bovine graft. Thereafter, endovascular internal trapping using coils was conducted. Severe headache developed at postoperative day 17, and the patient was diagnosed with eosinophilic meningitis. After administration of a high-dose corticosteroid for 2 weeks, her symptoms and laboratory findings were improved.

LESSONS

Postoperative eosinophilic meningitis is rarely related to craniotomy without using bovine graft. Neurosurgeons should consider the possibility of eosinophilic meningitis after craniotomy without a xenogeneic dural material.

Prospective Registry of Embolization of Intracranial Aneurysms Using HydroSoft Coils: Results of the Japanese HydroSoft Registry

BACKGROUND

The effect of HydroSoft coils on the prevention of recanalization and thrombosis after embolization is unclear. We herein report the results of the single-armed prospective Japanese HydroSoft Registry.

METHODS

Aneurysms with a diameter of <10 mm that were treated with a ≥50% length of HydroSoft coils were registered. We evaluated the safety and recanalization rate and analyzed the factors related to their recanalization and thrombosis 1 year later.

RESULTS

In total, 122 aneurysms were registered. Their mean maximum diameter and neck length were 6.4 and 3.9 mm, respectively. The mean length of the HydroSoft coils was 84.3%. No intracranial hemorrhage occurred, but 2 patients developed minor ischemic strokes. Angiographic examination immediately after the procedure showed complete obliteration, neck remnant (NR), and body filling (BF) in 20 (16.4%), 32 (26.2%), and 67 (54.9%) cases, respectively. One-year follow-up angiography showed complete obliteration, NR, and BF in 68 (55.7%), 15 (12.3%), and 15 (12.3%) cases, respectively, and 5 aneurysms (4.1%) were recanalized (4 and 1 with BF and NR as their initial angiographic result, respectively). Another 11 aneurysms still showed BF, although their thrombosis was promoted. No significant factors related to recanalization were identified. A high volume embolization ratio and small neck were significantly associated with thrombosis 1 year after embolization with HydroSoft coils.

CONCLUSIONS

The safety and prevention of recanalization 1 year after the treatment appeared acceptable. The high volume embolization ratio associated with HydroSoft coils could induce progression of thrombosis for aneurysms characterized by NR and BF during the follow-up period.

Hemodynamic Differences Between Recurrent and Nonrecurrent Intracranial Aneurysms: Fluid Dynamics Simulations Based on MR Angiography

BACKGROUND AND PURPOSE

Although the role of wall shear stress (WSS) in the initiation, growth, and rupture of intracranial aneurysms has been well studied, its influence on aneurysm recurrence after endovascular treatment requires further investigation. We aimed to compare WSS at necks of recurrent and nonrecurrent aneurysms.

METHODS

Nine recurrent coil-embolized aneurysms were identified and matched with nine nonrecurrent aneurysms. Patient-specific vessel geometries reconstructed from follow-up 3-D time-of-flight magnetic resonance angiography were analyzed using computational fluid dynamics (CFD) simulations. Absolute WSS and the percentage of abnormally low and high WSS at the aneurysm neck compared to the near artery were measured.

RESULTS

The median percentage of abnormal WSS at the aneurysm neck was 49.3% for recurrent and 34.7% for nonrecurrent aneurysms (P = .011). The area under the receiver-operating-characteristic curve for distinguishing these aneurysms according to the percentage of abnormal WSS was .86 (95% CI .62 to .98). The optimal cut-off value of 45.1% resulted in a sensitivity and a specificity of 88.89% (95% CI 51.8% to 99.7%).

CONCLUSION

Our findings indicate that necks of recurrent aneurysms are exposed to abnormal WSS to a larger extent. Abnormal WSS may serve as a metric to distinguish them from nonrecurrent aneurysms with CFD simulations a priori.

GREAT-a randomized controlled trial comparing HydroSoft/HydroFrame and bare platinum coils for endovascular aneurysm treatment: procedural safety and core-lab-assessedangiographic results

INTRODUCTION

Hybrid hydrogel-platinum coils (HydroCoil) have proven effective for endovascular aneurysm treatment. To overcome technical limitations (coil stiffness, time restriction for placement), a second generation of softer hydrogel coils has been brought to clinical practice (HydroSoft, HydroFrame). We report on procedural safety and core-lab-assessed angiographic results from an open-label multicenter randomized controlled trial.

METHODS

Web-based randomization occurred in 15 medical centers in France and seven in Germany between coil embolization with second-generation hydrogel coils and treatment with any bare platinum coil. Assist devices could be used as clinically required. Primary endpoint is a composite outcome including major aneurysm recurrence and poor clinical outcome at 18 months follow-up.

RESULTS

Five hundred thirteen patients were randomized (hydrogel n = 256, bare platinum n = 257). Twenty patients were excluded for missing informed consent and nine patients for treatment related criteria. Four hundred eighty-four patients were analyzed as randomized (hydrogel n = 243, bare platinum n = 241). Two hundred eight had ruptured aneurysms (43 %). Prespecified procedural complications occurred in 58 subjects (hydrogel n = 28, bare platinum n = 30, p = 0.77). The 14-day mortality rate was 2.1 % in both arms of the study. The median calculated packing densities for aneurysms assigned to hydrogel and bare platinum were 39 and 31 % respectively (p < 0.001). No statistically significant differences were found between arms in the post procedural angiographic occlusion rate (p = 0.8).

CONCLUSION

Second-generation hydrogel coils can be used in a wide spectrum of aneurysms with a risk profile equivalent to bare platinum. Packing density was significantly higher in aneurysms treated with hydrogel coils.

TRIAL REGISTRATION

http://www.germanctr.de , DRKS00003132.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

KEY POINTS

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

Follow-up of cerebral aneurysm embolization with hydrogel embolic system: Systematic review and meta-analysis

BACKGROUND

Hydrogel embolic system (HES) for endovascular treatment of cerebral aneurysms was developed to reduce the risk of aneurysm recurrence and the rate of retreatment. The aim of this systematic review was to verify the efficacy of HES, also in comparison to bare platinum coils (BPC).

MATERIAL AND METHODS

A systematic literature search was performed by two independent reviewers for articles published until January 31st, 2013 on the follow-up recurrence rate of intracranial aneurysm embolization with hydrogel-coated coils.

RESULTS

Thirteen articles on the use of HES for embolization of cerebral aneurysms were included in this study, for a total of 1683 embolized aneurysms. Significant heterogeneity was found regarding patient populations, methods of aneurysm coiling, follow-up schedules, and recurrence definitions. The pooled rate of initial complete aneurysm occlusion was 55% (95%CI, 38-70%); 59% (95%CI, 43-74%) in the subgroup of aneurysms treated with the use of HES. The pooled total recurrence rate was 19% (95%CI, 15-24%); 17% (95%CI, 14-22%) in the HES-treated subgroup. The pooled major recurrence rate was 12% (95%CI, 8-18%); 11% (95%CI, 7-16%) in the HES-treated subgroup. Comparing both types of coils, the pooled odds ratio for total recurrence was 0.63 (95%CI, 0.45-0.88; p=0.008) in favor of HES.

CONCLUSIONS

Embolization of cerebral aneurysms using HES seems to result in a lower rate of recurrence than that obtained using BPC, which is in line with the only randomized controlled trial. High-quality prospective studies are needed to define specific indications for the use of hydrogel-coated coils.

GREAT-a randomized aneurysm trial. Design of a randomized controlled multicenter study comparing HydroSoft/HydroFrame and bare platinum coils for endovascular aneurysm treatment

The effectiveness of a hybrid hydrogel platinum detachable coil (HydroCoil; MicroVention Inc., Tustin, CA) for endovascular aneurysm treatment has been proven in a recently published RCT. Due to technical restrictions (coil stiffness, time restriction for placement), the HydroSoft coil as well as a corresponding 3D framing coil, the HydroFrame coil (MicroVention Inc., Tustin, CA), a class of new softer coils containing less hydrogel and swelling more slowly than the HydroCoil, have been developed and brought to clinical practice. The present study aims to compare the effectiveness of endovascular aneurysm treatment with coil embolization between patients allocated HydroSoft/HydroFrame versus bare platinum coiling. GREAT is a randomized, controlled, multicentre trial in patients bearing cerebral aneurysms to be treated by coil embolization. Eligible patients were randomized to either coil embolization with HydroSoft/HydroFrame coils (>50 % of administered coil length), or bare platinum coils. Inclusion criteria were as follows: age 18-75, ruptured aneurysm (WFNS 1-3) and unruptured aneurysm with a diameter between 4 and 12 mm. Anatomy such that endovascular coil occlusion deemed possible and willingness of the neurointerventionalist to use either HydroSoft/HydroFrame or bare platinum coils. Exclusion criteria were as follows: aneurysms previously treated by coiling or clipping. Primary endpoint is a composite of major aneurysm recurrence on follow-up angiography and poor clinical outcome (modified Rankin scale 3 or higher), both assessed at 18 months post treatment. Risk differences for poor outcomes will be estimated in a modified intention-to-treat analysis stratified by rupture status (DRKS-ID: DRKS00003132).

Surgical recanalization of distal middle cerebral artery occlusion due to a coil migration during endovascular coil embolization: a case report

Coil migration into the parent artery during endovascular coil embolization is a rare, but life-threatening complication, which can induce thromboembolism and result in poor outcome. A 63-year-old man was referred to Chonbuk National University Hospital emergency center due to migration of a coil for a left middle cerebral artery bifurcation unruptured aneurysm. We performed an emergency craniectomy to remove the coil migrated to the distal M2 branch and thrombus, and aneurysmal neck clipping for his aneurysm. Fortunately, at the six month follow-up, the patient did not show any noticeable neurological sequela. In case of parent artery occlusion due to coil migration an immediate recanalization should be performed by a neurovascular specialist who can provide both surgical treatment and endovascular management in order to prevent severe sequela or even death.

Mid-term outcome of intracranial aneurysms treated with HydroSoft coils compared to historical controls treated with bare platinum coils: a single-center experience

BACKGROUND

HydroSoft (MicroVention, Aliso Viejo, CA), a hydrogel-platinum coil hybrid device, is one of various efforts to overcome recanalization of coiled intracranial aneurysms. The purpose of this study was to evaluate the efficacy and safety of the HydroSoft coils in patients with intracranial aneurysms, and to compare the 12-month outcomes with that of bare platinum coils.

METHODS

Four-hundred one patients harboring 430 intracranial aneurysms underwent endovascular embolization with the HydroSoft coils. In the control group, 221 patients harboring 253 aneurysms underwent coil embolization with bare platinum coils. The authors compared the degree of occlusion of the aneurysms, packing attenuations, procedural-related complications, and 12-month follow-up results between the two groups.

RESULTS

There were no significant differences of initial angiographic outcomes and procedure-related complications between the HydroSoft-coil group and the bare-coil group. Mean volumetric packing density of the HydroSoft-coil group was significantly higher than that of the bare platinum coil group (36.0 ± 8.50 % versus 32.1 ± 8.22 %, p < 0.001). The retreatment was performed in four (1.8 %) of 225 followed-up aneurysms among the HydroSoft coil group and 20 (8.8 %) of 227 followed-up aneurysms among the bare platinum coil group (p = 0.001, Fischer's exact test). Multivariate Poisson regression revealed that coil embolization using the HydroSoft coil significantly reduces the retreatment rate of coiled aneurysms at 12-month follow-up (adjusted RR, 0.21; 95 % CI, 0.07-0.64; p = 0.004).

CONCLUSION

Coil embolization using HydroSoft coils achieves higher volumetric packing density. Twelve-month follow-up data favors HydroSoft coils, with lower retreatment rates.

Aneurysm Recurrence Volumetry Is More Sensitive than Visual Evaluation of Aneurysm Recurrences

PURPOSE

Considerable inter-observer variability in the visual assessment of aneurysm recurrences limits its use as an outcome parameter evaluating new coil generations. The purpose of this study was to compare visual assessment of aneurysm recurrences and aneurysm recurrence volumetry with an example dataset of HydroSoft coils (HSC) versus bare platinum coils (BPC).

METHODS

For this retrospective study, 3-dimensional time-of-flight magnetic resonance angiography datasets acquired 6 and 12 months after endovascular therapy using BPC only or mainly HSC were analyzed. Aneurysm recurrence volumes were visually rated by two observersas well as quantified by subtraction of the datasets after intensity-based rigid registration.

RESULTS

A total of 297 aneurysms were analyzed (BPC: 169, HSC: 128). Recurrences were detected by aneurysm recurrence volumetry in 9 of 128 (7.0 %) treated with HSC and in 24 of 169 (14.2 %) treated with BPC (odds ratio: 2.39, 95 % confidence interval: 1.05-5.48; P = 0.039). Aneurysm recurrence volumetry revealed an excellent correlation between observers (Cronbach's alpha = 0.93). In contrast, no significant difference in aneurysm recurrence was found for visual assessment (3.9 % in HSC cases and 4.7 % in BPC cases). Recurrences were observed in aneurysms smaller than the sample median in 10 of 33 (30.3 %) by aneurysm recurrence volumetry and in 1 of 13 (7.7 %) by visual assessment.

CONCLUSIONS

Aneurysm recurrences were detected more frequently by aneurysm recurrence volumetry when compared with visual assessment. By using aneurysm recurrence volumetry, differences between treatment groups were detected with higher sensitivity and inter-observer validity probably because of the higher detection rate of recurrences in small aneurysms.

Design and biocompatibility of endovascular aneurysm filling devices

The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.

Coil type does not affect angiographic follow-up outcomes of cerebral aneurysm coiling: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Previous studies varied in their conclusions about the superiority of second-generation coils compared with bare platinum. In this systematic review and meta-analysis, we assessed differences in reported unfavorable angiographic outcomes of cerebral aneurysms treated with coil embolization as a function of coil type.

MATERIALS AND METHODS

This systematic review covered 1999-2011 through the use of Ovid MEDLINE and EMBASE. Search terms were "subarachnoid hemorrhage," "intracranial aneurysms," "endovascular treatment," and "coiling." Inclusion criteria were studies reporting >50 aneurysms with imaging follow-up. We defined "unfavorable angiographic outcome" as either "recanalization," <90% occlusion, or "incomplete occlusion" at follow-up. Rates of unfavorable outcomes were pooled through the use of random effects models and compared across various coil types. Multivariate random effects meta-regression models were used to further explore the differences in outcomes related to coil type.

RESULTS

We included 82 studies, comprising 90 patient cohorts, among which, 65 (72%) used bare platinum coils, 8 (8.9%) used Matrix, 11 (12%) used HydroCoil, and 6 (6.7%) used Cerecyte. The overall unfavorable outcome rate was 19% (95% CI: 17%,21%). Unfavorable outcome rates were 20% (95% CI: 17%, 22%) for bare platinum coils, 23% (95% CI: 16%, 29%) for Matrix, 15% (95% CI: 9%, 21%) for HydroCoil, and 15% (95% CI: 7%, 23%) for Cerecyte, respectively. The difference in unfavorable outcome rates among the various coil types was not statistically significant after adjusting for baseline characteristics, including aneurysm size, rupture status, and follow-up duration.

CONCLUSIONS

The rate of unfavorable angiographic outcomes was not statistically different across the major approved coil types. The quality of the evidence, however, remains low because of high heterogeneity, small sample size, and potential publication bias.

Differences in the angiographic evaluation of coiled cerebral aneurysms between a core laboratory reader and operators: results of the Cerecyte Coil Trial

BACKGROUND AND PURPOSE

Independent evaluation of angiographic images is becoming widely applied in the assessment of treatment outcomes of cerebral aneurysms. In the current study, we assessed the agreement between an independent core laboratory and the operators regarding angiographic appearance in a recent randomized, controlled trial.

MATERIALS AND METHODS

Data were derived from the Cerecyte Coil Trial. Angiographic images of each coiled aneurysm, taken immediately after embolization and at 5- to 7-month follow-up, were evaluated by the operator at the treating center and by an independent neuroradiologist at the core laboratory. For the purpose of this study, images were interpreted on a 3-point scale to provide uniformity for analysis; grade 1: complete occlusion, grade 2: neck remnant; and grade 3: sac filling. "Unfavorable angiographic appearance" was defined as grade 3 at follow-up or interval worsening of grade between the 2 time points.

RESULTS

The study included 434 aneurysms. Immediately after embolization, grade 3 was reported by operators in 39 (9%) compared with 52 (12%) by the core laboratory (P = .159). On follow-up, grade 3 was reported by operators in 44 (10%) compared with 81 (19%) by the core laboratory (P < .0001). Overall, operators noted unfavorable angiographic appearance in 78 (18%) compared with 134 (31%) by the core laboratory (P < .0001). At every time point, agreement between the core laboratory and the operators was slight.

CONCLUSIONS

Unfavorable angiographic appearance was noted almost twice as frequently by an independent core laboratory as compared with the operators. Planning of trials and interpretation of published studies should be done with careful attention to the mode of angiographic appearance interpretation.

Does stent implantation improve the result of repeat embolization in recanalized aneurysms?

BACKGROUND

Although endovascular technique and related devices continue to improve, recanalization of embolized aneurysm remains a pitfall of this approach. The problem of how to treat the recanalized aneurysm needs to be addressed.

OBJECTIVE

To determine the outcomes of patients undergoing repeat embolization for recanalized intracranial aneurysms and to evaluate the impact of stent implantation on subsequent recanalization.

METHODS

Between September 2001 and September 2011, we performed endovascular retreatment in 162 patients with a total of 197 recanalized intracranial aneurysms. Stent implantation was performed in 68 aneurysms during the retreatment. Clinical and morphological outcomes were assessed at 6 months or more after repeat embolization.

RESULTS

Procedure-related complications, including asymptomatic thromboembolism, occurred with 15 aneurysms (7.6%) without permanent neurological sequelae. Follow-up imaging of 172 aneurysms documented stable occlusion in 96 of the lesions (55.8%), minor recanalization in 17 (9.9%), and major recanalization in 59 (34.3%) during the mean follow-up period of 26.0 ± 18.0 months. In multiple logistic regression analysis, stent implantation was shown to reduce the major recanalization rate at 6 months after retreatment (odds ratio: 0.161; 95% confidence interval:, 0.038-0.670; P = .012) and thereafter (odds ratio: 0.226; 95% confidence interval: 0.088-0.581; P = .002).

CONCLUSION

Stent implantation, as well as compact coil packing, at the time of repeat embolization seems beneficial in reducing rates of further recanalization.

Initial experience with an extremely soft bare platinum coil, ED coil-10 Extra Soft, for endovascular treatment of cerebral aneurysms

BACKGROUND AND PURPOSE

The ED coil-10 Extra Soft (EDC-10 ES) is an extremely soft coil with excellent operability for embolization of cerebral aneurysms and is frequently used as a 'finishing coil'. The aim of this study was to evaluate the efficacy and safety of this coil.

METHODS

Clinical data were analyzed retrospectively for 92 consecutive aneurysms for which at least one EDC-10 ES was used. Follow-up angiography at 6 months was available for 69 aneurysms. Initial and follow-up outcomes were evaluated using three-category occlusion grading. Factors that affect the packing density were also investigated.

RESULTS

Of the 92 aneurysms, 63 (68.5%) were classified as complete occlusion, 11 (12.0%) as having a neck remnant and 18 (19.6%) with dome filling immediately after the embolization procedure. The mean ± SD packing density was 29.5 ± 10.6%. Periprocedural complications were observed in three cases (3.3%). At 6 months the rate of completely occluded cases increased to 78.3% (54/69) and those for neck remnant and dome filling decreased to 11.8% (8/69) and 10.1% (7/69), respectively. Recanalization occurred in six aneurysms and one aneurysm was retreated during the follow-up period, giving an overall recurrence rate of 10.0% (7/70). Linear regression analysis showed a significant association of packing density with the percentage EDC-10 ES volume (p<0.001) and with the maximum aneurysm size (p<0.001).

CONCLUSIONS

Use of the EDC-10 ES permits safe and effective embolization of a cerebral aneurysm and contributes to a reduction in the rate of recanalization.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed. These materials were investigated for the repair of cartilage, bone, adipose tissue, intervertebral disc, neural, and cardiac tissue. Papers from the last ten years were considered, with a particular focus on the advances of the last five years. A critical discussion is centered on new perspectives and challenges in the regeneration of specific tissues, with the aim of highlighting the limits of current systems and possible future advancements.