Bioabsorbable polymeric material coils for embolization of intracranial aneurysms: a preliminary experimental study

Imaging of intracranial aneurysms in animals: a systematic review of modalities

Intracranial aneurysm (IA) animal models are paramount to study IA pathophysiology and to test new endovascular treatments. A number of in vivo imaging modalities are available to characterize IAs at different stages of development in these animal models. This review describes existing in vivo imaging techniques used so far to visualize IAs in animal models. We systematically searched for studies containing in vivo imaging of induced IAs in animal models in PubMed and SPIE Digital library databases between 1 January 1945 and 13 July 2022. A total of 170 studies were retrieved and reviewed in detail, and information on the IA animal model, the objective of the study, and the imaging modality used was collected. A variety of methods to surgically construct or endogenously induce IAs in animals were identified, and 88% of the reviewed studies used surgical methods. The large majority of IA imaging in animals was performed for 4 reasons: basic research for IA models, testing of new IA treatment modalities, research on IA in vivo imaging of IAs, and research on IA pathophysiology. Six different imaging techniques were identified: conventional catheter angiography, computed tomography angiography, magnetic resonance angiography, hemodynamic imaging, optical coherence tomography, and fluorescence imaging. This review presents and discusses the advantages and disadvantages of all in vivo IA imaging techniques used in animal models to help future IA studies finding the most appropriate IA imaging modality and animal model to answer their research question.

Lumen-oriented versus wall-oriented treatment strategies for intracranial aneurysms - A systematic review of suggested therapeutic concepts

The development of new treatment strategies for intracranial aneurysms (IAs) has been and continues to be a major interest in neurovascular research. Initial treatment concepts were mainly based on a physical-mechanistic disease understanding for IA occlusion (lumen-oriented therapies). However, a growing body of literature indicates the important role of aneurysm wall biology (wall-oriented therapies) for complete IA obliteration. This systematic literature review identified studies that explored endovascular treatment strategies for aneurysm treatment in a preclinical setting. Of 5278 publications screened, 641 studies were included, categorized, and screened for eventual translation in a clinical trial. Lumen-oriented strategies included (1) enhanced intraluminal thrombus organization, (2) enhanced intraluminal packing, (3) bridging of the intraluminal space, and (4) other, alternative concepts. Wall-oriented strategies included (1) stimulation of proliferative response, (2) prevention of aneurysm wall cell injury, (3) inhibition of inflammation and oxidative stress, and (4) inhibition of extracellular matrix degradation. Overall, lumen-oriented strategies numerically still dominate over wall-oriented strategies. Among the plethora of suggested preclinical treatment strategies, only a small minority were translated into clinically applicable concepts (36 of 400 lumen-oriented and 6 of 241 wall-oriented). This systematic review provides a comprehensive overview that may provide a starting point for the development of new treatment strategies.

Recovery of Visual Loss Following Internal Trapping of Anterior Cerebral Artery (A1 Segment) for Partially Thrombosed Large Anterior Communicating Artery Aneurysm: A Case Report

A 60-year-old woman, who experienced progressive right visual loss, was diagnosed with an unruptured large cerebral aneurysm. Magnetic resonance imaging (MRI) and angiography revealed a large partially thrombosed anterior communicating artery (Acom) aneurysm. The aneurysmal neck was located at the junction of the left A1–A2 segments, and the aneurysmal dome communicated with the right A1–A2 junction by the Acom. Endovascular treatment using the flow alteration technique was selected. Following an oral antiplatelet therapy for 9 days, balloon test occlusion (BTO) of the medial portion of the left A1 segment was performed under local anesthesia. After confirming the tolerance of the BTO, internal trapping of the medial portion of the left A1 segment by detachable coils was performed following intra-aneurysmal coil embolization. Oral antiplatelet treatment was continued for 19 days postoperatively. Within 3 months following the operation, her right visual acuity dramatically improved to the original level. Owing to aneurysmal recanalization and the disappearance of the thrombus, the second and third embolization was performed through the Acom route, 4 months and 3 years following the first embolization, respectively, and followed up for an additional 7 years by MRI; no deterioration of her visual acuity and no aneurysmal recanalization was observed. Thus, endosaccular embolization combined with flow alteration is considered a useful alternative treatment for large and partially thrombosed Acom aneurysms.

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.

Progressive Occlusion of Small Saccular Aneurysms Incompletely Occluded After Stent-Assisted Coil Embolization : Analysis of Related Factors and Long-Term Outcomes

PURPOSE

Incompletely occluded aneurysms after coil embolization are subject to recanalization but occasionally progress to a totally occluded state. Deployed stents may actually promote thrombosis of coiled aneurysms. We evaluated outcomes of small aneurysms (<10 mm) wherein saccular filling with contrast medium was evident after stent-assisted coiling, assessing factors implicated in subsequent progressive occlusion.

METHODS

Between September 2012 and June 2016, a total of 463 intracranial aneurysms were treated by stent-assisted coil embolization. Of these, 132 small saccular aneurysms displayed saccular filling with contrast medium in the immediate aftermath of coiling. Progressive thrombosis was defined as complete aneurysmal occlusion at the 6‑month follow-up point. Rates of progressive occlusion and factors predisposing to this were analyzed via binary logistic regression.

RESULTS

In 101 (76.5%) of the 132 intracranial aneurysms, complete occlusion was observed in follow-up imaging studies at 6 months. Binary logistic regression analysis indicated that progressive occlusion was linked to smaller neck diameter (odds ratio [OR] = 1.533; p = 0.003), hyperlipidemia (OR = 3.329; p = 0.036) and stent type (p = 0.031). The LVIS stent is especially susceptible to progressive thrombosis, more so than Neuroform (OR = 0.098; p = 0.008) or Enterprise (OR = 0.317; p = 0.098) stents. In 57 instances of progressive thrombosis, followed for ≥12 months (mean 25.0 ± 10.7 months), 56 (98.2%) were stable, with minor recanalization noted once (1.8%) and no major recanalization.

CONCLUSION

Aneurysms associated with smaller diameter necks, hyperlipidemic states and LVIS stent deployment may be inclined to possible thrombosis, if occlusion immediately after stent-assisted coil embolization is incomplete. In such instances, excellent long-term durability is anticipated.

Level of Headaches After Surgical Aneurysm Clipping Decreases Significantly Faster Compared to Endovascular Coiled Patients

In incidental aneurysms, endovascular treatment can lead to post-procedural headaches. We studied the difference of surgical clipping vs. endovascular coiling in concern to post-procedural headaches in patients with ruptured aneurysms. Sixty-seven patients with aneurysmal subarachnoidal haemorrhage were treated in our department from September 1^st 2015 - September 1^st 2016. 43 Patients were included in the study and the rest was excluded because of late recovery or high-grade subarachnoid bleedings. Twenty-two were surgical treated and twenty-one were interventionally treated. We compared the post-procedural headaches at the time points of 24 h, 21 days, and 3 months after treatment using the visual analog scale (VAS) for pain. After surgical clipping the headache score decreased for 8.8 points in the VAS, whereas the endovascular treated population showed a decrease of headaches of 3.3 points. This difference was highly statistical significant and remained significant even after 3 weeks where the pain score for the surgically treated patients was 0.68 and for the endovascular treated 1.8. After 3 months the pain was less than 1 for both groups with surgically treated patients scoring 0.1 and endovascular treated patients 0.9 (not significant). Clipping is relieving the headaches of patients with aneurysm rupture faster and more effective than endovascular coiling. This effect stays significant for at least 3 weeks and plays a crucial role in stress relieve during the acute and subacute ICU care of such patients.

Characteristics of Headache After an Intracranial Endovascular Procedure: A Prospective Observational Study

BACKGROUND

Two editions of the International Classification of Headache Disorders (ICHD) diagnostic criteria for "Headache attributed to an intracranial endovascular procedure" have been published, in 2004 and 2013.^1,2 Despite studies that have suggested that the former is not very practical, the ICHD-3 beta did not contain major changes. Moreover, so far no consensus exists regarding characteristics of headache after intracranial endovascular procedure. Thus, there is a need for sound suggestions to improve the ICHD-3 beta diagnostic criteria.

METHODS

Using a prospective design, we identified consecutive patients with unruptured intracranial aneurysms (UIAs) with neuroendovascular treatment from January 2014 to December 2014.

RESULTS

In total, 73 patients were enrolled, and 58 patients ultimately completed the 6-month follow-up. After the procedure, five of the 29 patients (17.2%) with pre-existing headache experienced marked worsening after the procedure, while seven of the 29 patients without prior headache developed new-onset headache post-procedurally. The headaches started within 24 hours, with a mean duration of 24-72 hours. The headaches were moderate to severe. The eligibility of these events to be considered headaches caused by neuroendovascular procedures according to the ICHD-3 beta diagnostic criteria for designation was far from ideal.

CONCLUSIONS

Most cases of markedly worsening headaches and new-onset headaches started within 24 hours and persisted longer than that specified in the ICHD-3 beta diagnostic criteria. Moreover, considering that some items are not very practical, the ICHD-3 beta diagnostic criteria should be revised in the light of recent literature reports.

Innovation in Neurosurgery: Intellectual Property Strategy and Academia/Industrial Collaboration

Neurosurgery has tremendous possibilities for development of innovative medical devices. However, most of the neurosurgical devices used in Japan are imported products. Promotion and development of domestic medical devices is highly encouraged and it is one of the pillars of Prime Minister Shinzo Abe's growth strategy of Japanese economy. Innovative "Made in Japan" medical devices can be developed by interdisciplinary collaboration between industries and academic institutions. Proper orientation of medical and engineering education, social and administrative awareness of the need of facilitating the medical devices creative process with corresponding regulatory changes, and appropriate medical and technological infrastructure establishment are needed for stimulating medical device innovation.

Comparison of shape memory polymer foam versus bare metal coil treatments in an in vivo porcine sidewall aneurysm model

The endovascular delivery of platinum alloy bare metal coils has been widely adapted to treat intracranial aneurysms. Despite the widespread clinical use of this technique, numerous suboptimal outcomes are possible. These may include chronic inflammation, low volume filling, coil compaction, and recanalization, all of which can lead to aneurysm recurrence, need for retreatment, and/or potential rupture. This study evaluates a treatment alternative in which polyurethane shape memory polymer (SMP) foam is used as an embolic aneurysm filler. The performance of this treatment method was compared to that of bare metal coils in a head-to-head in vivo study utilizing a porcine vein pouch aneurysm model. After 90 and 180 days post-treatment, gross and histological observations were used to assess aneurysm healing. At 90 days, the foam-treated aneurysms were at an advanced stage of healing compared to the coil-treated aneurysms and showed no signs of chronic inflammation. At 180 days, the foam-treated aneurysms exhibited an 89-93% reduction in cross-sectional area; whereas coiled aneurysms displayed an 18-34% area reduction. The superior healing in the foam-treated aneurysms at earlier stages suggests that SMP foam may be a viable alternative to current treatment methods. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1892-1905, 2017.

Headache, cerebral aneurysms, and the use of triptans and ergot derivatives

BACKGROUND

Uncertainty exists regarding the correlation between unruptured cerebral aneurysms and their role in headache etiology. It is also unclear whether surgical endovascular treatment may improve or worsen the headache, and if there are predictable factors for headache outcome such as pre-existing headache features, aneurysm characteristics, or other medical history. There is debate regarding safe treatment of migraine in patients with aneurysms, both before and after endovascular treatments. Particularly, there is hesitancy to use the triptans and ergot derivatives such as dihydroergotamine because of their vasoconstrictive effects and concern for adverse events related to the aneurysm such as aneurysmal instability and rupture.

OBJECTIVE

To review the literature regarding the anatomy, pathophysiology, and association between headache, untreated vs surgically treated aneurysms, and the use of triptans and ergot derivatives for migraine treatment in this setting.

CONCLUSION

Associations between some headaches and aneurysms may exist. Some chronic headaches may respond to surgical aneurysm repair while others may worsen. These associations are undefined by current literature because of variable results, study methods, and limited data. Prospective studies are needed which incorporate pre- and post-procedure headache character and diagnosis, aneurysm characteristics, type of aneurysm repair, associated risk factors for worsening post-procedure headache, and ultimately combining all of these data to better predict headache outcome following surgical aneurysm treatment. Lastly, the caution and avoidance of triptan and ergot derivative use for migraine in the setting of aneurysm is not supported by the current evidence, and much of this concern may be excessive and unwarranted, although more evidence confirming safety is needed.

Polymeric embolization coil of bilayered polyvinyl alcohol strand for therapeutic vascular occlusion: a feasibility study in canine experimental vascular models

PURPOSE

To investigate the feasibility of polyvinyl alcohol (PVA) polymer coil as a new endovascular embolic agent and to gauge the related histologic response in a canine vascular model.

MATERIALS AND METHODS

PVA polymer coil was fabricated by cross-linking PVA and tantalum particles. Basic properties were then studied in vitro via swelling ratio and bending diameter. Normal renal segmental arteries and wide-necked aneurysms of carotid sidewalls served as canine vascular models. Endovascular PVA coil embolization of normal renal segmental arteries (N = 20) and carotid aneurysms (N = 8) was performed under fluoroscopic guidance in 10 dogs. Degree of occlusion was assessed immediately and at 4 weeks after embolization by conventional and computed tomographic angiography. Histologic features were also graded at acute (day 1, six segmental arteries and four aneurysms) and chronic phases (week 4, 14 segmental arteries and four aneurysms) after embolization to assess inflammation, organization of thrombus, and neointimal proliferation.

RESULTS

Swelling ratio declined as concentrations of cross-linking agent increased. Mean bending diameters were 2.05 mm (range, 0.86-6.25 mm) in water at 37 °C and 2.29 mm (range, 0.94-6.38 mm) in canine blood samples at 37 °C. Occlusion of normal renal segmental arteries was sustained (complete occlusion at day 1, n = 20; at week 4, n = 14), whereas immediate outcomes in carotid aneurysms (day 1, complete occlusion, n = 5; residual neck only, n = 3) were not sustained (week 4, complete occlusion, n = 1; minor recanalization, n = 1; major recanalization, n = 2). At week 4, chronic inflammatory cells predominated, with progressive organization of thrombus and fibrocellular ingrowth. All aneurysms bore full neointimal linings on the coil mass in the chronic phase.

CONCLUSIONS

Vascular occlusion by PVA polymer coil proved superior in normal renal segmental arteries and feasible in surgically constructed carotid aneurysms (with packing densities ≥ 30%), constituting acceptable radiologic feasibility and histologic response.

Incidence and risk factors of postoperative headache after endovascular coil embolization of unruptured intracranial aneurysms

BACKGROUND

Endovascular coil embolization for unruptured intracranial aneurysms (UIAs) has gained popularity because of its low morbidity and mortality in a short-term context. However, Headache is sometimes brought about or worsened after endovascular treatment, and this complaint may lead to perplexing situations, albeit infrequently. The aim of this study is to estimate the practical incidence and risk factors of postoperative headache in patients with endovascular embolization of UIAs.

METHOD

One hundred and thirty patients who underwent endovascular treatment of UIAs between March 2006 and May 2012 were enrolled according to inclusion criteria. From a retrospective chart review, the patients who had worsening or newly developed headache from postoperative day 1 to in-hospital stay were investigated for analyzing risk factors of post-embolization headache. Factors based on patients' demographics, anatomical and radiological features of the lesions, treatment, utilized devices and outcome were investigated, and statistically verified.

RESULTS

Headache occurred or was exacerbated in 32 patients (24.6 %). Of these, 30 patients showed improvement within days, but two patients with previous migraine history complained of intermittent headache over 3 months after the embolization. Univariate comparison between the headache group and the non-headache group showed that internal carotid artery (ICA) segment aneurysm, stent-assisted coiling, and no history of hypertension were associated with post-embolization headache (p < 0.05). However, stent-assisted coiling and no history of hypertension were significantly associated with post-embolization headache in logistic regression analysis (p < 0.05).

CONCLUSIONS

In the current study, stent-assisted coiling and no history of hypertension were important risk factors for headache in patients undergoing endovascular coil embolization for UIAs. Further investigations are still necessary to confirm the correlation of other factors which did not reach statistical significance in post-embolization headache in this limited study.

In vivo response to an implanted shape memory polyurethane foam in a porcine aneurysm model

Cerebral aneurysms treated by traditional endovascular methods using platinum coils have a tendency to be unstable, either due to chronic inflammation, compaction of coils, or growth of the aneurysm. We propose to use alternate filling methods for the treatment of intracranial aneurysms using polyurethane-based shape memory polymer (SMP) foams. SMP polyurethane foams were surgically implanted in a porcine aneurysm model to determine biocompatibility, localized thrombogenicity, and their ability to serve as a stable filler material within an aneurysm. The degree of healing was evaluated via gross observation, histopathology, and low vacuum scanning electron microscopy imaging after 0, 30, and 90 days. Clotting was initiated within the SMP foam at time 0 (<1 h exposure to blood before euthanization), partial healing was observed at 30 days, and almost complete healing had occurred at 90 days in vivo, with minimal inflammatory response.

Endovascular treatment of subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a common and devastating form of stroke. A large number of patients with aSAH develop angiographic or clinical vasospasm responsible for high morbidity and mortality. Rapid advances in the field of interventional neurology and the development of minimally invasive techniques have resulted in expansion of potential therapeutic applications. Treatment of aSAH has benefited from this rapid advance in the field of endovascular therapies. In the first section of the review, we discuss the therapeutic options and techniques for embolizations of intracranial aneurysms. In the second section, we discuss evolving endovascular treatment methods employed to intervene in delayed complications of cerebral vasospasm in patients with aSAH.

Effect of endovascular treatment on headache in elderly patients with unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

The incidence of unruptured intracranial aneurysms is increasing in the elderly population as life expectancy increases, and patients often present with headache. The goal of this study was to determine the effect of endovascular treatment on headache and identify factors associated with headache outcome in elderly patients with unruptured intracranial aneurysms.

MATERIALS AND METHODS

A retrospective study was conducted for elderly patients (≥ 65 years old) being treated for unruptured intracranial aneurysms. Headache assessment was performed by a quantitative 11-point headache scale in all patients before and after endovascular treatment. Factors associated with headache outcome were investigated by univariate analyses.

RESULTS

A total of 72 patients (mean age, 70.0 years; age range, 65-80 years; 41 women) fulfilled the inclusion criteria. There were 52 patients (72.2%) who presented with preoperative headache (headache score ≥ 1). Among them, 40 (76.9%) reported that headache score had an improvement according to their self-reported quantitative headache score after endovascular treatment. The average headache score was 5.63 preoperatively vs 2.50 postoperatively (P = .000). Twenty patients (27.8%) had no headache before treatment (headache score = 0), of whom 2 (10.0%) reported new onset of headache postoperatively. Only a preoperative headache score was associated with treatment outcome of headache, and a higher headache score predicted a lack of headache relief after endovascular treatment (P = .003).

CONCLUSIONS

Endovascular coiling of unruptured intracranial aneurysms resulted in relief of headache in most of the elderly patients. Preoperative headache score was the only statistically significant predictor of headache outcome.

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.

Suitability of cerebral aneurysms for endovascular treatment: Evolution of criteria with technological developments

With the introduction of electrically detachable coils in 1991 and later the results of the ISAT trial in 2002, endovascular approach became the primary treatment for cerebral aneurysms in many countries. The suboptimal quality of anatomical results and the relatively high rate of aneurysm recurrence after treatment still hamper an even more widespread of the technique. In this paper, we will make a review of the anatomical factors associated with poor anatomical results as well as technological developments aiming at improvement of aneurysm healing.

Mid-term clinical and angiographic results of cerebral aneurisms treated with matrix2(®) coils

OBJECTIVE

To evaluate 1 year results of endovascular treatment (EVT) of intracranial aneurisms using Matrix second generation detachable coils (MSG(®)).

PATIENTS AND METHODS

Between January and December 2006, 32 patients with 32 intracranial aneurisms were treated by coiling using MSG(®), with a minimum follow-up of 1 year. Data were acquired prospectively. Exclusion criteria were: permanent adjunctive device, less than 50% MSG(®) length, and additional bioactive or coated coils. All procedures were carried out in a single institution. Six months and 1 year follow-up were performed with magnetic resonance angiography and digital subtraction angiography, respectively. We assessed radiological and clinical results using the modified Raymond classification, a 3-level longitudinal grading scale (LGS), Glasgow outcome and Rankin scales.

RESULTS

Thirteen (40.6%) male and 19 (59.4%) female underwent EVT using MSG(®) with a mean follow-up of 16.6 months. Ruptured aneurisms (75%) outnumbered unruptured. Immediate radiological results showed 15 complete occlusions (46.9%), 12 (37.5%) neck remnant, and five (15.6%) residual sac. In the mean time, six patients (18.7%) needed to be retreated due to insufficient initial packing or early recanalization. Using the LGS, a stable occlusion was observed in 40.7%, a progressive thrombosis in 25%, and 34.3% of the cases evolved unfavorably. Thirty-one patients had stable or improved clinical status, while one patient died from a thromboembolic event 1 month after retreatment (3.1% overall mortality).

CONCLUSION

At 1 year follow-up, MSG(®) demonstrated similar angiographic results compared to Matrix first generation coils and didn't suggest advantage over platinum coils.

Matrix² coils in embolization of intracranial aneurysms: 1-year outcome and comparison with bare platinum coil group in a single institution

BACKGROUND AND PURPOSE

The endosaccular occlusion by using BPC has been useful in the treatment of intracranial aneurysms, but its limited durability remains a deep-seated drawback. The Matrix² coil, one of the bioactive-coated coils, had been developed to improve this limited durability. To evaluate durability of Matrix² coils after embolization of intracranial aneurysms, we retrospectively compared 1-year outcomes with that of BPC groups.

MATERIALS AND METHODS

A group of 121 aneurysms in 114 patients were embolized by using Matrix² coils between April 2006 and September 2008. The BPC group consisted of 151 aneurysms in 137 patients embolized by using BPCs alone between October 2007 and October 2008. The initial outcomes including packing densities, occlusion grades, and periprocedural complications, and the 1-year outcomes on MR angiography were retrospectively compared between the 2 groups.

RESULTS

The Matrix² coil group and BPC group with similar baseline demographic characteristics revealed comparable initial outcomes. The rates of overall recurrence, major recanalization, and retreatment were 17.4%, 14.0%, and 10.7% versus 7.3%, 5.3%, and 4.6%, respectively (P = .066). However, the rates of subgroups with aneurysm volumes between 50 and 200 mm³ were 23.7%, 13.1%, and 10.5% versus 2.2%, 0%, and 0% (P = .022), respectively. The rates of subgroups with packing attenuation <30% were 38.3%, 31.9%, and 23.4% versus 13.3%, 11.7%, and 10% (P = .025), respectively. There were no differences in packing attenuation (P = .152), initial occlusion grade (P = .098), and 1-year outcomes (P = .209) according to the length of Matrix² coils used.

CONCLUSIONS

Overall, initial and 1-year outcomes of the Matrix² coil group were comparable to those of the BPC group. However, in certain subgroups of aneurysm volume and packing attenuation, the 1-year durability of Matrix² coils was inferior to that of the BPC group.

Bioactive coils cause headache and fever after endovascular treatment of intracranial aneurysms

BACKGROUND

Based on our encounters with patients who have been treated for unruptured intracranial aneurysms by endovascular coil embolization using bioactive coils, we observed that such patients often present with headaches and fever.

OBJECTIVE

The purpose of this study was to evaluate the incidence of headache and fever after coil embolization using bioactive coils.

METHODS

A database of 92 intracranial unruptured aneurysm patients (88 patients who did not have chronic headaches or migraines before treatment) on whom coil embolization had been performed between July 2007 and October 2010 was retrospectively assessed. Forty-five aneurysms (43 patients) were treated using bioactive coils and the other aneurysms were treated using bare coils. We analyzed the incidence and duration of headache, temperature, C-reactive protein, and white blood cell count before and after coil embolization and compared the 2 groups.

RESULTS

Forty-one patients (46.6%) reported onset of headaches just after treatment. Headache incidences were significantly greater in the patients treated with bioactive coils (bioactive coil group: 62.8% [27/43] vs bare coil group: 31.1% [14/45], P = .003), and the duration of headaches was significantly longer in the bioactive coil group (bioactive coil group: 3.44 ± 1.22 days vs bare coil group: 2.40 ± 1.17 days, P = .027). Seventy-one patients (80.7%) had incidences of fever (over 37°C) after treatment (bioactive coil group: 83.7% [36/43] vs bare coil group: 77.8% [35/45], P = .663). The duration of fever was significantly longer in the bioactive coil group (bioactive coil group: 2.9 ± 1.4 days vs bare coil group: 1.9 ± 1.1 days, P = .0017), and temperatures at 1, 2, or 3 days after treatment were significantly higher in the bioactive coil group (respective temperatures at 1, 2, 3 days after treatment: bioactive coil group: 37.42 ± 0.49, 37.19 ± 0.45, 37.00 ± 0.49 vs bare coil group: 37.14 ± 0.38, 36.96 ± 0.41, 36.63 ± 0.51, P = .009, P = .0246, P = .0032). There were no significant differences in C-reactive protein level and white blood cell count 1 and 3 days after treatment between 2 groups.

CONCLUSIONS

Bioactive coils induce headache and fever after coil embolization for intracranial aneurysms due to the inflammatory effects of polyglycolic acid used to accelerate aneurysm fibrosis and neointimal formation.

Endovascular management of intracranial aneurysms

Data from our clinical series and others supports the idea that endovascular coil embolization is a reliable form of treatment for both ruptured and unruptured cerebral aneurysms. This form of treatment appears from preliminary data to be protective against subarachnoid hemorrhage. Although not likely to replace open surgery, the continued advancements in technology and supportive clinical data will allow endovascular therapy to become a more durable mode of treatment.

Clinical experience with Matrix2 360 degrees coils in the treatment of 100 intracranial aneurysms

BACKGROUND

The M2-360 degrees is a recent class of aneurysm coil. This device combines the second generation of bioactive copolymer coating, which is intended to promote aneurysm fibrosis, with the "360 degrees " design, which is meant to improve uniformity and density of packing. This study evaluates the safety and angiographic stability of these devices.

METHODS

This was a retrospective review of 86 consecutive patients with 100 intracranial aneurysms that were treated using M2-360 degrees s. Follow-up was done at 6 and 12 months.

RESULTS

Seventy-eight aneurysms were coiled solely with M2-360 degrees s, and 22 aneurysms were treated with a combination of coils. In mixed-coil cases, the average percentage of coil volume consisting of M2-360 degrees coils was 78%. Procedure-related neurologic complications occurred in 6 patients (7%). Initial complete occlusion was obtained in 80 aneurysms. Of 76 aneurysms with 6-month angiographic follow-up, 4 (5.3%) revealed further occlusion, 54 (71.1%) were unchanged, and 18 (23.7%) showed recanalization. Of 38 aneurysms with 12-month follow-up, 1 (2.6%) revealed further occlusion, 23 (60.5%) were unchanged, and 14 (36.8%) showed recanalization. Six- and 12-month angiograms showed major recanalization (requiring further coiling) in 3.9% and 15.8% of cases, respectively.

CONCLUSIONS

The risk of complications with M2-360 degrees -treated aneurysms is comparable with reports of other coils, indicating that M2-360 degrees s are relatively safe. Although the initial occlusion rate is higher than that in other coiling series, recanalization rates were similar to those obtained with other coil designs. This study does not demonstrate an advantage with M2-360 degrees s.

Evaluation of the new HydroSoft coil in a canine model of bifurcation aneurysm

Object

The present study was designed to evaluate the new HydroSoft coil as a finishing coil in a canine model of a wide-necked, high-flow bifurcation aneurysm.

Methods

Nine experimental aneurysms were created. The aneurysm dome was first embolized with bare platinum coils and HydroCoils, and then the remaining neck portion was embolized with HydroSoft coils to obtain maximum aneurysm occlusion. Follow-up angiography was performed at 1 and 3 months, and histopathological analysis was performed after the 3-month follow-up angiography.

Results

One hundred twenty-five HydroSoft coils were deployed into 9 aneurysms without any technical problem. The mean volume % of the bare platinum coils, HydroCoils, and HydroSoft coils were 23.0 ± 15.9, 63.0 ± 23.5, and 13.9 ± 8.9%, respectively. The mean aneurysm volumetric occlusion rate was 45.9%. At the 3-month follow-up angiography, 8 of 9 aneurysms remained stable and had not recanalized. Microscopically, most aneurysms showed complete endothelialization and thick neointima formation at the neck surface with no thrombus present.

Conclusions

The HydroSoft coil appears feasible as a finishing coil based on the results of this animal study. HydroSoft coils inserted at the neck of the aneurysm may help induce neointima formation, which may lead to less coil compaction and aneurysm recanalization in clinical practice.

Shape memory polymer foams for cerebral aneurysm reparation: effects of plasma sterilization on physical properties and cytocompatibility

Shape memory polyurethanes (SMPUs) represent promising candidate materials for aneurysm embolization, since they could enable clinical problems still associated with these clinical procedures to be overcome. In this work, we report on the characterization of physicochemical, thermomechanical and in vitro interface properties of two SMPU foams (Cold Hibernated Elastic Memory, CHEM), proposed as a material for embolization devices in minimally invasive procedures. Moreover, because device sterilization is mandatory for in vivo applications, effects on the properties of the foams after plasma sterilization were also evaluated. Both foams (CHEM 3520 and CHEM 5520) showed excellent shape recovery ability (recovery rate, R(r), up to 99%) in conventional shape recovery tests, performed at constant heating rate. Transition temperatures (T(trans)), determined by tandelta peaks in dynamic mechanical analysis (DMA), were 32.2 and 45.1 degrees C, for CHEM 3520 and 5520, respectively. The value of T(trans) affects shape memory ability in the recovery test at 37 degrees C, which simulates the behavior after implantation of the device: in fact, R(r) was significantly higher for lower T(trans) foam (R(r) approximately 82% and R(r) approximately 46%, respectively, for CHEM 3520 and CHEM 5520). After plasma sterilization performed by a Sterrad sterilization system, an increase in open porosity was observed: this is probably due to the sterilization cycle; however, no effects on shape recovery behavior were observed. Furthermore, plasma treatment had no significant effect on L929 cells in in vitro cytotoxicity tests, performed on cell culture medium extracts in contact with foams for up to 7 days. Moreover, direct cytocompatibility tests showed a good colonization and growth from L929 cells on CHEM foams, suggesting the effectiveness of an in vivo healing process. All these results seem to suggest that CHEM foams could be advantageously used for manufacturing devices for mini-invasive embolization procedures of aneurysms.

Endovascular treatment of intracranial aneurysms using Matrix coils: short- and mid-term results in ruptured and unruptured aneurysms

OBJECTIVE

A prospective multicenter registry was conducted in France to evaluate the safety and efficacy of Matrix coils (Boston Scientific Neurovascular, Fremont, CA). The short- and mid-term results are presented.

METHODS

From January to October 2004, 236 patients harboring ruptured (Group I) or unruptured (Group II) aneurysms were treated via an endovascular approach with Matrix coils and were included in this registry. In-hospital morbidity and mortality was determined. One-year clinical follow-up data were obtained in 218 patients (92.4%). One-year angiographic follow-up data were obtained in 165 patients (171 aneurysms, 70.1%).

RESULTS

In Group I, in-hospital morbidity and mortality rates were 5.8 and 6.5%, respectively, with a procedure-related morbidity and mortality of 3.6 and 1.4%, respectively. At 1 year, the morbidity and mortality rates were 2.4 and 11.0%, respectively. In Group II, procedure-related morbidity and mortality rates were 1.0 and 0.0%, respectively. At 1 year, the morbidity and mortality rates were 1.1 and 0%, respectively. For both groups, no bleeding or rebleeding was observed during the follow-up period. The only factor associated with an increased rate of complications was delay before treatment of more than 2 days after bleeding. Aneurysm recanalization was observed in 44 aneurysms (25.7%).

CONCLUSION

In-hospital and 1-year morbidity and mortality rates in patients harboring ruptured or unruptured aneurysms treated with Matrix coils were similar to those previously reported with the use of bare coils. The efficacy of Matrix coils to prevent aneurysm recanalization was not demonstrated, despite a high percentage of progressive thrombosis that suggests biological activity resulting from Matrix coils.

Interval change in size of venous pouch canine bifurcation aneurysms over a 10-month period

BACKGROUND AND PURPOSE

The natural history study of experimental aneurysms is important for the evaluation of new endovascular occlusion devices. Our purpose was to evaluate the natural history of experimental venous pouch bifurcation aneurysms in mongrel dogs up to a 10-month period.

MATERIALS AND METHODS

Serial digital subtraction angiography was performed in 5 bifurcation aneurysms 1, 4, 7, and 10 months after surgical creation. Aneurysm dimensions, including height, width, and neck diameter, and animal body weights were measured. Comparisons of each parameter were performed using the Friedman test and the paired Wilcoxon signed-rank test.

RESULTS

Four of 5 aneurysms were patent during a 10-month follow-up period. One aneurysm was regarded as a partially thrombosed aneurysm at 1 month, though the extent of partial thrombosis lessened at 10 months. Bifurcation aneurysms progressively increased in size (aneurysm height, width, and neck diameter) during the first several months.

CONCLUSION

If this experimental model is used to evaluate new endovascular devices for cerebral aneurysm treatment, investigators should be aware of early progressive aneurysm enlargement.

INITIAL EXPERIENCE WITH BIOACTIVE CERECYTE DETACHABLE COILS

OBJECTIVE

Despite proven safety of endovascular coil embolization of intracranial aneurysms, the potential need for retreatment remains criticized. The goal of this prospective study was to assess the safety, durability, and effect on recanalization rates of the Cerecyte (Micrus Corp., Sunnyvale, CA) bioactive coil.

METHODS

Two hundred twelve ruptured and unruptured aneurysms in 176 patients were prospectively enrolled in a database registry during a 12-month period. Adverse clinical outcomes directly attributed to the use of the Cerecyte coil were documented. Angiographic outcomes were determined immediately after coil embolization and during follow-up studies. All patients who received stent assistance or a non-Cerecyte coil were excluded. Two independent endovascular surgeons reviewed follow-up films. Any discrepancy was deemed a recurrence.

RESULTS

After exclusion criteria, 81 patients with 89 aneurysms were available for a minimum of 6 months of follow-up. Of those 89 aneurysms, 65% were ruptured aneurysms and were treated in the acute setting. The mean size of the aneurysm was 7 mm. The mean angiographic follow-up period was 11.2 months. Recurrences requiring retreatment as a result of dome filling were identified in six aneurysms (6.7%). Four aneurysms (4%) developed compaction of more than 20%, which was defined as interstitial filling of the fundus. There was one thromboembolic event leading to permanent neurological deficit. No cases of chemical meningitis or delayed hydrocephalus occurred.

CONCLUSION

The Cerecyte bioactive coil seems to be safe and effective for use in both ruptured and unruptured aneurysms. The bioactive polymer within the coils allows similar handling characteristics of a bare platinum coil. Studies to assess long-term outcomes with direct comparison to platinum coils and alternative bioactive coils are warranted.

Re-treatment of patients with embolized ruptured intracranial aneurysms

BACKGROUND

Although one third of patients with intracranial aneurysms treated by GDC embolization manifest recanalization, a strategy for their subsequent treatment remains to be established. We evaluated the efficacy and safety of additional treatments performed after the first coil embolization.

METHODS

We treated 168 patients with acute ruptured intracranial aneurysms by GDC embolization, which was stopped when angiography confirmed complete obliteration. We recorded the type and number of all GDCs introduced for aneurysm occlusion and obtained follow-up cerebral angiograms at 6 months and 1 and 2 years postembolization. Patients with major coil compaction that had not disappeared at 2 years after the first embolization underwent re-treatment.

RESULTS

During the follow-up period, 18 (10.7%) of the 168 patients underwent additional therapy. In 16, we performed second (n = 14) or more than 2 repeated (n = 2) coil placement procedures for the same aneurysm. One patient died after the fourth coil embolization. Two patients underwent surgery; their aneurysms showed no change in the degree of occlusion on follow-up angiograms.

CONCLUSION

The additional treatment of previously coil-embolized aneurysms is safe, and the strategy of regular follow-ups is effective.

Current status and future prospect of endovascular neurosurgery

Recently, due to the evolution of technology, the field of neurosurgery is receiving spotlight. In particular endovascular neurosurgery has gained a great interest along with the advancement of the modern neurosurgery. The most remarkable advances were made in embolization of the cerebral aneurysms, arteriovenous malformations and intracranial stenosis during the past 10 years. These advances will further change the role of neurosurgeons in treating cerebrovascular disease. Because interventional neuroradiologists have performed most of procedures in the past, neurosurgeons have been deprived of chances to learn endovascular procedure. This article discusses the development of technological aspect of endovascular neurosurgery in chronological order. By understanding the history and current status of the endovascular surgery, the future of neurosurgery will be promising.

Endovascular treatment of intracranial aneurysms with matrix detachable coils: midterm anatomic follow-up from a prospective multicenter registry

BACKGROUND AND PURPOSE

Polyglycolic/polylactic acid-covered platinum coils have been proposed to reduce the rate of aneurysm recanalization after endovascular treatment. A prospective and multicenter registry was conducted in France to evaluate the safety and short-term and midterm efficacy of Matrix coils. This analysis focused on anatomic midterm results.

MATERIALS AND METHODS

Two hundred thirty-six patients harboring 244 ruptured or unruptured aneurysms treated via endovascular approach by using Matrix coils were included in this registry. Treatment was totally or partially performed by using Matrix coils. Anatomic results were evaluated on postoperative and last-follow-up digital subtraction angiography (DSA) by using the Raymond scale. "Recanalization" was defined as worsening, and "progressive thrombosis" was defined as improvement on the Raymond scale.

RESULTS

Anatomic midterm follow-up was obtained in 165 of 236 patients (70%) harboring 171 aneurysms (range, 6-27 months; mean, 14 +/- 4 months). At midterm follow-up angiography, 79 aneurysms were completely occluded (46.2%), 43 had a neck remnant (25.1%), and 49 had an aneurysm remnant (28.7%). Of 171 aneurysms, recanalization was observed in 44 patients (25.7%), including major recanalization in 18 patients (10.5%). Recanalization was more frequent if the embolized volume of aneurysm was </=25%. Progressive thrombosis was observed in 52 aneurysms (30%). No bleeding or rebleeding was observed during the period of follow-up.

CONCLUSION

The efficacy of Matrix coils in preventing recanalization was not demonstrated in our series. In agreement with previous studies using bare platinum coils, volumic occlusion was an important feature for the prediction of aneurysm recanalization. A high percentage of progressive thrombosis in incompletely treated aneurysms was observed in our series, suggesting a biologic activity of Matrix coils.

Preliminary investigation of calcium alginate gel as a biocompatible material for endovascular aneurysm embolization in vivo

OBJECTIVE

We sought to expand our assessment of calcium alginate as an embolic agent in an aneurysm model in swine that survived from 30 to 90 days. The objective of this study was to assess the biocompatibility and stability of calcium alginate in aneurysms in vivo.

METHODS

Ten models were created from a venous pouch sutured to the carotid artery, simulating flow to a side-wall aneurysm. Eight swine received complete embolizations, and two were less than 50% embolized to be used as controls. Alginate and calcium chloride were injected from concentric-tube microcatheters to form a mass that filled the aneurysm pouch.

RESULTS

Angiography and histology verified complete aneurysm occlusion and neck healing up to 90 days in eight swine. Both control animal aneurysms ruptured within 8 days. No animals showed evidence of downstream calcium alginate gel propagation. A minor bioactive response to the alginate gel was noted at 30 days, and fibrous tissue grew over the aneurysm orifice, sealing off the defect. No degenerative or inflammatory response was observed. At 90 days, moderate fibrous tissue surrounded the alginate. Tissue growth across the aneurysm neck remained complete and stable with no signs of neointimal growth into the parent vessel.

CONCLUSION

Calcium alginate was an effective endovascular occlusion material that filled the aneurysm and provided an effective template for tissue growth across the aneurysm neck after 30 days and up to 90 days. Complete filling of the aneurysm with calcium alginate ensures stability, biocompatibility, and optimal healing for up to 90 days in swine.

A Polyvinyl Alcohol Core Coil Containing Basic Fibroblast Growth Factor Evaluated in Rabbits with Aneurysms Induced by Elastase

OBJECTIVE

The present study evaluates the effect of a novel coil with a polyvinyl alcohol (PVA) core that delivered basic fibroblast growth factor (bFGF) to aneurysms in rabbits induced by elastase.

METHODS

PVA was processed to form small threads and inserted into the central core of a primary coil (PVA-core coil). After immersion in saline or bFGF (500 or 2000 mug/ml), PVA-core coils were implanted into elastase-induced aneurysms in rabbits in vivo. Follow-up angiography was performed 4 and 8 weeks after embolization, and the effects were histologically semiquantified according to a grading scale.

RESULTS

Follow-up angiography showed that the coils did not compact or protrude and that clots did not form in any group. The score of gross neck healing was significantly higher in the 8-week 2000 bFGF group than in the 8-week PVA coil group (2.7 +/- 0.6 versus 0.0 +/- 0.0, P < 0.05). The dome healing score was significantly higher in the 4-week 2000 bFGF group than that of the 4-week PVA coil group (4.0 +/- 0.0 versus 2.7 +/- 0.6, P < 0.05). Cells positive for alpha-smooth muscle actin densely accumulated in the dome of the aneurysm embolized with PVA-core coils containing bFGF.

CONCLUSION

Implantation of the PVA-core coil containing bFGF accelerated tissue growth at the neck as well as in the dome of aneurysms induced by elastase in rabbits. These results suggested that PVA-core coils could prevent the recanalization of embolized aneurysms.

The effects of stenting and endothelial denudation on aneurysm and branch occlusion in experimental aneurysm models

BACKGROUND

Stents are increasingly used in the endovascular treatment of intracranial aneurysms. We studied the effects of stenting and endothelial denudation on aneurysm and branch vessel occlusion.

METHODS

Bilateral lingual bifurcation venous pouch aneurysms were created in eight dogs, surgically scraping the aneurysmal endothelial lining on one side. Both arteries were immediately stented using balloon-expandable stents. In four other dogs, a wide-neck carotid bifurcation aneurysm was created, with the vein pouch denuded or not (n=2 each), followed by immediate stenting. Results were compared using angiography and pathology at 10 days (n=2), 10 (n=8), and 20 weeks (n=2). Branch occlusion between initial and final angiograms was recorded. Pathological evaluation of aneurysms was studied, with attention to neointima formation at the aneurysm ostium and around branch vessel origins.

RESULTS

All stented and denuded lingual aneurysms were obliterated compared with two of eight lingual aneurysms that were stented alone (P=.007). None of the carotid bifurcation aneurysms became obliterated (0/4), but denuded aneurysms showed partial thrombosis (2/2). Of 68 total stent-covered branches, 5 (7%) were occluded and 17 (27%) had altered angiographic flow.

CONCLUSIONS

Stenting led to suboptimal results in the presence of an intact endothelial layer. Endothelial denudation can promote aneurysm occlusion when combined with stenting.

Endovascular management of intracranial aneurysms: current experience and future advances

OBJECTIVE

The past 15 years have seen a revolution in the treatment of intracranial aneurysms. Endovascular technology has evolved rapidly since the Food and Drug Administration approval of Guglielmi detachable coils in 1995, which now allows successful treatment of most aneurysms. The authors provide a review of their 11-year experience at Jefferson Hospital for Neuroscience with endovascular embolization of intracranial aneurysms and discuss clinical trial outcomes and future directions of this treatment method.

METHODS

The authors reviewed the clinical and angiographic outcomes for 1307 patients undergoing endovascular treatment of intracranial aneurysms. Their analysis focuses on posterior circulation and middle cerebral artery aneurysms, as well as cases of stent-assisted coil embolization. They review their procedural protocol and patient selection criteria for endovascular management.

RESULTS

Several large clinical trials have demonstrated the safety and efficacy of endovascular treatment of intracranial aneurysms. The International Subarachnoid Aneurysm Trial provides Level I evidence demonstrating a significant reduction in disability or death with endovascular treatment compared with surgical clipping. The most common procedural complications include intraprocedural rupture and thromboembolic events; avoidance strategies are also discussed. Vasospasm after subarachnoid hemorrhage causes neurological morbidity and mortality and can be successfully managed by early recognition and interventional treatment with angioplasty, pharmacologic agents, or both.

CONCLUSION

Long-term studies evaluating experience with aneurysm coil embolization during the past decade indicate that this is a safe and durable treatment method. The introduction of stent-assist techniques has improved the management of wide-neck aneurysms. Future technology developments will likely improve the durability of endovascular treatment further by delivering bioactive agents that promote aneurysm thrombosis beyond the coil mass alone. It is clear that endovascular therapy of both ruptured and unruptured aneurysms is becoming a mainstay of practice in this patient population. Although not replacing open surgery, the continued improvements have allowed aneurysms that previously were amenable only to open clip ligation to be treated safely with durable long-term outcomes.

Historical perspectives: the microsurgical and endovascular treatment of aneurysms

The history of aneurysm therapy is rich in parallelisms that exist between the once-fledgling field of aneurysm surgery and the now-growing field of endovascular aneurysm treatment. The treatment of aneurysms has had a cyclic progression. The indirect and safest approach to the treatment of aneurysms was seen in the development and use of Hunterian ligation in the 19th century. During the past few decades, nascent technology and a better understanding of the pathophysiology of aneurysms resulted in a more direct intracranial, extravascular approach to aneurysm therapy, with the focal point being the use of the aneurysm clip to secure an aneurysm at its neck. Interestingly, alternative and, arguably, even more direct approaches to aneurysm therapy developed in the surgical suites. These techniques became the seeds for the birth of direct endovascular aneurysm treatment in particular and endovascular surgery in general. As endovascular technology continues to develop, somewhat more sophisticated, indirect approaches to aneurysm therapy (the use of stents to modify flow, for example) are being investigated. The treatment of intracranial aneurysms has a rich history. First thought to be inoperable lesions, aneurysms have challenged neurosurgeons and their colleagues since they were first recognized in the 18th century. Treatment for these lesions did not begin until the 19th century with the use of Hunterian ligation. This review describes the many milestones in the field of aneurysm surgery and endovascular surgery, tracing the many parallelisms contained within the birth and growth of each field and their respective significance.

Initial clinical experience with matrix detachable coils for the treatment of intracranial aneurysms

OBJECT

The Matrix detachable coil is a new bioactive, bioabsorbable coil used in the endovascular embolization of intracranial aneurysms. It has a platinum core covered with a bioactive, bioabsorbable polymer (polyglycolic acid/lactide). The authors report on their initial midterm clinical experience with the first-generation Matrix detachable coil.

METHODS

One hundred twelve patients harboring 118 aneurysms were treated using Matrix coils. Forty-nine aneurysms (41.5%) were associated with acute subarachnoid hemorrhage (SAH). Twenty-four lesions (49%) were harbored by patients with Hunt and Hess Grade I, 11 (23.4%) by patients with Grade II, eight (16.3%) by those with Grade III, and six (12.2%) by those with Grade IV. Four aneurysms (3.4%) were harbored by patients who had presented with nonacute SAH. Sixty-five aneurysms (55%) were unruptured. Fifty-seven lesions (48.3%) were small with a small neck, 29 (24.6%) were small with a wide neck, 30 (25.4%) were large, and two (1.7%) were giant. All patients were followed up to obtain angiography and clinical outcome data. Technical complications occurred in six patients: two thromboembolic complications and four aneurysm perforations. Of these six patients, the status of two deteriorated because of aneurysm perforation and another two because of thrombus formation (morbidity 3.6%). There were five deaths--one due to rerupture after embolization. Angiography follow-up studies of 87 aneurysms were obtained. Seventy aneurysms demonstrated progressive occlusion or a stable neck (80.5%), and 17 had some degree of recanalization (19.5%). The aneurysms originally diagnosed as a neck remnant showed a 15% rate of recanalization.

CONCLUSIONS

Matrix coils can be delivered into aneurysms with technical complications similar to those encountered using GDCs. Midterm anatomical outcomes to date have shown moderate improvement in the recanalization rate when compared with those realized using the GDC system. Because of the increased friction associated with the first-generation Matrix coil, the packing density in most aneurysms was less than that achieved with GDCs. Prolonged angiography follow-up evaluations are needed to document long-term efficacy.

Clinical and angiographic outcome of intracranial aneurysms treated with Matrix detachable coils in Chinese patients

BACKGROUND

Aneurysm recurrence is an innate problem in endovascular treatment of aneurysms with coils. A coated coil system named Matrix (Boston Scientific Neurovascular, Fremont, CA), covered with a bioabsorbable polymeric material (polyglycolide/lactide copolymer [PGLA]), was developed to accelerate intraaneurysmal clot organization and fibrosis. The purpose of this study was to evaluate the efficacy and safety of the Matrix detachable coils in patients with intracranial aneurysms and aneurysmal recurrence rate.

METHODS

In a regional neurosurgical center in Hong Kong, data of patients undergoing endovascular embolization of intracranial aneurysm was collected. In a 20-month period, 42 patients with 44 aneurysms were treated by endovascular embolization using matrix coils alone or mixed with bare platinum coils. Thirty-four patients presented with ruptured aneurysms, and 8 patients presented with unruptured aneurysms.

RESULTS

Twenty-five patients (60%) had 6-month follow-up DSA, and 10 patients (24%) had 18-month follow-up DSA. Seven aneurysm recurrences were identified, amounting to 16% for all aneurysms and 14% for ruptured aneurysms. Four patients were treated by repeated embolization, and 2 patients were treated by microsurgical clipping. Two adverse events due to thromboembolism were noted. One 78-year-old lady with poor-grade subarachnoid hemorrhage treated by partial embolization died from rebleed at day 4. Another patient with partial embolization and spontaneous thrombosis of dorsal wall ICA aneurysm died at 2 months with aneurysm recanalization with rerupture. Twenty-six patients achieved favorable outcome (GOS score 4 or 5) at last follow-up. The aneurysm recurrence rate using bare platinum coils of the same center was 11% and 7% for all aneurysms and ruptured aneurysms, respectively.

CONCLUSION

Matrix coil embolization was safe, but there was no reduction in aneurysm recurrence using matrix coils alone or mixed with GDCs, compared with GDCs alone.

Effects of stenting the parent artery on aneurysm filling and gene expression of various potential factors involved in healing of experimental aneurysms

SUMMARY

Intracranial stents are increasingly used in the endovascular treatment of aneurysms, but very little is known regarding their effect on the cellular and molecular evolution of aneurysms. Bilateral venous pouch lateral wall carotid aneurysms were created in 20 dogs. All dogs then underwent angiography and balloon-expandable stenting of one aneurysm four to six weeks later. Fifteen dogs underwent aneurysm harvesting at one day (n=3), four days (n=4), seven days (n=3), and 14 days (n=5) for mRNA expression analysis, using axial sections taken from the aneurysm neck and fundus for RTPCR amplification of four cytokines or growth factors: TNF-a, TGF-b1, MCP-1, and PDGFBB; two adhesion molecules: VCAM-1 and PECAM-1; five matrix modifying agents; MMP- 2, 9, TIMPs 1, 3, 4, and two cellular markers: CD34 and a-SMA. Five other dogs, sacrificed at 12 weeks, were examined for extent of filling of the aneurysm neck with organized tissue and for neointima formation at the aneurysm ostium. Angiography was performed prior to sacrifice in all animals, and compared with initial studies. Eleven out of 20 stented aneurysms showed a favorable angiographic evolution, while none of the 20 nonstented aneurysms improved (p=0.001). Pathology showed partially occluded aneurysms, with neointima formation around the stent struts.Observed trends in mRNA expression, that stenting increased expression of genes involved in organization and neointima formation, agreed with experimental hypotheses, but differences between stented and non-stented aneurysms did not reach statistical significance. Parent vessel stenting was associated with angiographic improvement of aneurysm appearance. Modifications in mRNA expression patterns following stenting deserve further study to better establish potential molecular targets to promote aneurysm healing.

Assessment of Matrix coils in a canine model of a large bifurcation aneurysm

INTRODUCTION

Controversy exists as to whether Matrix coils are an improvement over bare platinum coils in preventing aneurysm recanalization in endosaccularly coiled large aneurysms. We investigated Matrix coils in a dog model of a wide-necked large bifurcation aneurysm.

METHODS

Six experimental aneurysms were created in dogs and these aneurysms were endosaccularly coiled with 100% Matrix coils. Angiographic and histopathological data were analyzed at 2 weeks and at 3 months.

RESULTS

Average aneurysm dimensions were length 17.8 mm, width 8.3 mm, and neck 6.2 mm. Aneurysm coil filling ranged 24.1-41.8% by volume. At 14 days, three of six Matrix-treated aneurysms showed coil compaction and aneurysm recanalization. At 3 months, one additional Matrix-treated aneurysm showed delayed coil compaction and aneurysm recanalization. At 3 months, in three harvested aneurysms, the average measured neck neointima was 0.150 +/- 0.14 mm. However, in two of the three aneurysms harvested at 3 months, aneurysm recanalization had occurred with neointimal tissue not completely covering the aneurysm orifice. Thick connective fibrous intercoil tissue was observed. No immediate or delayed thrombus formation had occurred.

CONCLUSION

Based on limited data in an experimental bifurcation aneurysm in dogs, Matrix coils appear to induce a thicker aneurysm neck neointima tissue and intercoil granulation response but appear prone to coil compaction and aneurysm recanalization. Modifications to the Matrix coil are likely needed to improve angiographic results in large aneurysms.

Acceleration of Aneurysm Healing by Hollow Fiber Enabling the Controlled Release of Basic Fibroblast Growth Factor

OBJECTIVE

The objective of this study was to develop an embolization material of hollow fiber combined with gelatin hydrogel for the controlled release of basic fibroblast growth factor (bFGF). We examined feasibility of the material in embolization healing aneurysm by bFGF-induced tissue organization.

METHODS

An aneurysm was prepared at the common carotid artery of 60 rabbits by the end-to-side anastomosis of jugular venous pouch. The hollow fibers combined with or without 100 microg free bFGF or gelatin hydrogel incorporating 0, 10, 50, or 100 microg bFGF were applied to the aneurysm. Tissue appearance or histological observation was performed 1, 2, 3, and 6 weeks after application to evaluate the area embolized by fibrous organization in the aneurysm and the neointima formation at the aneurysm orifice.

RESULTS

When applied with the hollow fibers combined with gelatin hydrogel containing 100 microg bFGF, the aneurysm was histologically occupied by fibrous tissue newly formed 3 weeks later, whereas neointima was formed at the aneurysm orifice. The histological area occupied by fibrous tissue was significantly larger than that of hollow fibers combined with 100 microg bFGF. No influence of bFGF dose on the aneurysm healing by the fibers combined with hydrogels incorporating bFGF was observed.

CONCLUSION

Local, controlled release of bFGF from the hollow fibers combined with gelatin hydrogel incorporating bFGF accelerated the aneurysm healing by tissue organization.

Angiographic and clinical results in 316 coil-treated basilar artery bifurcation aneurysms

Object. The aim of this study was to analyze the effect of the endovascular treatment of basilar artery (BA) bifurcation aneurysms and to compare the results with those published by other neuroendovascular teams.

Methods. The authors performed a retrospective analysis of 316 aneurysms of the BA bifurcation that had been treated using endovascular coil occlusion between November 6, 1992, and February 12, 2005. After the initial embolization procedure, a 90 to 100% occlusion rate was achieved in 86% of the aneurysms. No complication was evident in 80% of the lesions, although periprocedural aneurysm rupture (3.2%) and thromboembolic events (12.3%) were the most frequent complications. Clinical outcome according to the Glasgow Outcome Scale (GOS) was a score of 5 or 4 in 77%, 3 in 11%, 2 in 5%, and 1 in 7% of patients. Initial follow-up angiography studies were obtained in 56% of patients at a mean of 19 months posttreatment and demonstrated a 90 to 100% occlusion rate in 70%. No recurrence was seen on 65% of the aneurysms. Coil compaction was evident on 24% of the follow-up angiograms.

A second treatment was performed on 48 aneurysms (15%) a mean of 27 months after the first therapeutic session and resulted in 90 to 100% occlusion in 83% of the lesions. Complications were encountered in 19% of the aneurysms. Rupture did not occur during any of the procedures. Clinical outcome was rated as GOS Score 5 or 4 in 83% of the patients and Grade 3 in 17%.

During a cumulative clinical follow up of 821 years in 237 patients, 182 patients (81%) were independent (GOS Score 5 or 4), 33 (14%) were dependent (GOS Score 3), eight (3%) were in a vegetative state, and two (1%) had died. Clinical outcome was significantly worse after previous aneurysm rupture and following procedural complications.

Conclusions. These results are within the range of published data for coil treatment of BA tip aneurysms and confirm both the safety and efficacy of this endovascular treatment method.

Tenascin-C—coated platinum coils for acceleration of organization of cavities and reduction of lumen size in a rat aneurysm model

Object. Detachable platinum coils are widely used in the endovascular treatment of intracranial aneurysms. The use of coil placement produces a higher incidence of aneurysm recurrence compared with surgical clipping. To reduce the incidence of recurrence by promoting clot organization, the authors designed a platinum coil coated with tenascin-C (TNC), an extracellular matrix glycoprotein, and then histologically examined tissue responses.

Methods. Platinum coils were prepared by successive coatings with cationic polyethyleneimine and anionic heparin and then TNC or basic fibroblast growth factor (bFGF) was immobilized by affinity binding to the heparin. Six unmodified, six heparin-coated, six bFGF-coated, or eight TNC-coated platinum coils were inserted into ligated common carotid arteries (CCAs) of adult male rats, and CCA segments were harvested after 14 or 28 days.

The percentages of organized areas occupying the luminal cavity in unmodified, heparin-coated, bFGF-coated, and TNC-coated groups were 4.8 ± 4.6, 1.6 ± 1.1, 17.9 ± 10.7, and 93.4 ± 6.9%, respectively. In addition, the mean lumen size in the TNC-coated group (0.35 ± 0.23 mm2) was reduced to less than half that of the unmodified group (0.72 ± 0.21 mm2). Immunohistochemical analysis revealed that α—smooth muscle actin—positive cells were a major cellular component of the organized tissue within the TNC-coated coils but not in the bFGF group. Collagen fibrils in the organized areas were also much thicker and denser with TNC-coated coils than with bFGF-coated coils.

Conclusions. Placement of TNC-coated coils can remarkably accelerate organization of luminal cavities and reduce their volume, providing improved efficacy of these coils for endovascular embolization.