Topic review: surface modifications enhancing biological activity of guglielmi detachable coils in treating intracranial aneurysms

BACKGROUND: Endovascular therapy with Guglielmi detachable coils is an accepted treatment option for patients with intracranial aneurysms. However, an emerging technology in the realm of endovascular tools is the use of traditional Guglielmi detachable coils with biologically active substances complexed to the coil surface to enhance aneurysm occlusion. METHODS: We review the literature and current trends in modified Guglielmi detachable coils. Surface modifications with extracellular matrix proteins, growth factors, ion impregnation, and genetically altered cells have been used in animal studies to improve the cellular response of Guglielmi detachable coils. Similarly, coronary artery stents have been modified in several different ways to maintain vessel patency, contrary to the goal of endovascular therapy. We comparatively reviewed this literature to add insight into the evolution of the research on modified Guglielmi detachable coils. CONCLUSIONS: Guglielmi detachable coil modifications have the potential to enhance aneurysm obliteration with directed cellular responses. This may allow aneurysm occlusion with coils in less time than untreated coils, thus decreasing the risks of aneurysm enlargement and hemorrhage.     

Current update on the endovascular management of intracranial aneurysms

Rapid technological advances in the endovascular field has revolutionized the treatment of intracranial aneurysms. Since the Food and Drug Administration approval of Guglielmi detachable coils in 1995, a variety of newer coils with different design and physical properties such as complex coils, stretch resistant and bioactive coils, have become available promising to increase packing density and decrease aneurysmal recurrence and recanalization rates. Treatment of wide neck intracranial aneurysms has improved with availability of compliant balloons and newer intracranial assist devices. Emerging technology such as flow diverters hold promise in treatment of large and difficult to treat intracranial aneurysms. Liquid embolic agent (Onyx HD 500) offer a novel, safe and effective adjunctive treatment option when used in combination with coils with stent and/or balloon assist technique. Endovascular treatment options have vastly expanded the armamentarium of neurosurgeons allowing safe and durable treatment of aneurysms previously amenable to clipping only.     

Endovascular treatment of 404 intracranial aneurysms treated with nexus detachable coils: short-term and mid-term results from a prospective,consecutive, European multicenter study

Background

Aneurysm recanalization remains a limitation of endovascular treatment. A new type of bioactive coil, the polyglycolic/polylactic acid-covered platinum microfilaments Nexus coil (ev3/Covidien, Irvine, CA, USA), has been proposed. The objective is to evaluate the safety and short-term and mid-term efficacy of Nexus coils in the endovascular treatment of intracranial aneurysms.

Methods

The ENDECOR (European Nexus Detachable Coil Registry) is the first prospective, consecutive, multicenter non-randomized registry. After providing informed consent, 390 patients (238 women and 152 men; mean age, 51.6 years) with 404 ruptured or unruptured aneurysms were enrolled at 34 centers. Treatment was performed with at least 75 % of coil length as Nexus coils. Clinical and technical complications were systematically reported. An independent core laboratory evaluated angiographic results by using the Raymond Grading Scale.

Results

Complete occlusion was seen in 181 aneurysms (48 %); neck remnant in 86 aneurysms (22 %) and aneurysm remnant in 111 aneurysms (30 %). Technical and clinical complications related to the procedure occurred in 33 patients (8.5 %). At discharge, overall mortality and permanent-morbidity were 4.1 % (16/390) and 5.6 % (14/251), respectively. Angiographic mean follow-up of 13.3 months was obtained in 233 of 390 patients (64.4 %) harboring 247 aneurysms. Recanalization was observed in 44 aneurysms (17.7 %), and progressive thrombosis was observed in 53 aneurysms (21.6 %).

Conclusions

Endovascular treatment of intracranial aneurysms with Nexus coils was associated with low morbidity and mortality rates. Efficacy of Nexus coils was comparable to published series of intracranial aneurysms treated with bare platinum coils, but their efficacy to prevent aneurysm recanalization was not demonstrated.     

Superior cerebellar artery aneurysms treated using the sole stenting approach. Technical note

Endovascular treatment of intracranial aneurysms has evolved since the introduction of detachable coils. Sole stenting is a brand-new technique that has recently emerged as a definitive treatment for saccular or fusiform aneurysms at particular locations. Superior cerebellar artery aneurysms are rare, and few treated cases have been reported. Most of them have been treated surgically, and endovascular cases usually have been managed with occlusion of the parent vessel. The authors report on the first two endovascularly treated cases with complete cure of the aneurysm as well as preservation of the parent vessel and distal circulation via the sole stenting technique. The results together with several aspects of the technique, such as the correction of the angle of the vessel and modification of the shear stress, are discussed.     

Surgery following endovascular coiling of intracranial aneurysms

BACKGROUND: Surgery for intracranial aneurysms that have been treated by endovascular coiling is a new challenge for neurosurgeons and the need for it will undoubtedly continue to increase. The indications for, timing, and technique of surgery in our experience are described. METHODS: We have reviewed our experience with 11 patients who underwent surgery following endovascular coiling with Guglielmi detachable coils (GDCs) of an aneurysm. We analyzed the indications for surgery, surgical techniques used, and patient outcome. RESULTS: There were nine female and two male patients. The mean age was 49 years (range 13 to 67 years). The intervals between coiling and surgery were 1, 2, 3, 4, 7, 7, 10, and 14 days, 6 weeks, 2, 18, and 25 months. The indications for surgery were partial treatment (3), growth of residual neck (2), persistent mass effect of a giant aneurysm (1), mass effect from the coil ball (2), coil migration (2), and coil protrusion with embolic event (1). The coils were removed at the time of surgery from 9 of 11 aneurysms before clipping. In two cases it was possible to place a clip across the neck of the aneurysm without removing the coils, as the coils no longer occupied the neck.There were two permanent deficits directly related to the endovascular procedures. Two other patients who presented with subarachnoid hemorrhage had residual neurological deficits post surgery and one patient with a giant aneurysm had persistent visual loss. CONCLUSION: Surgery remains a viable option at any time for treating aneurysms that have been previously treated by GDC placement. The operative approach is determined by the need for coil removal and the duration since coiling.     

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.     

Multiple intracranial aneurysms. Endovascular treatment by coils]

The authors report the case of a 30 years-old man presenting with 3 intracranial aneurysms, which were treated by endovascular techniques. The aneurysm responsible for two previous subarachnoid hemorrhages was a giant supracavernous left internal carotid artery aneurysm. Endovascular therapy using coils caused intraoperative rupture which was successfully managed by balloon occlusion of the internal carotid artery. The two other aneurysms (basilar top, and right middle cerebral artery) were small and asymptomatic; complete obliteration of both aneurysms was achieved by selective coils embolization. Persistent occlusion of the three aneurysms was documented ad six months angiographic follow up.     

Endovascular occlusion of intracranial aneurysms with Guglielmi detachable coils: correlation between coil packing density and coil compaction

Summary  This retrospective analysis was undertaken to evaluate a possible relationship between coil packing densitiy and coil compaction on intracranial aneurysms embolized using Guglielmi detachable coils (GDCs).  Of the patients who underwent endovascular surgery using GDC in our hospital between 1994 and 1998, 33 patients had endovascular treatment with GDC and were examined by follow-up angiography at least 12 months after surgery. They had coil embolization to the extent where aneurysms were no longer filled or only faintly filled as shown by cerebral angiography immediately after surgery.  At follow-up angiography, coil compaction was observed in 3 aneurysms. In all patients with coil compaction, the coil packing density was below 20% (14.5±4.0%). On the other hand, it was over 20% (25.7±4.7%) in all patients without coil compaction. In the 11 patients with a basilar bifurcation aneurysm, the coil packing density was over 24% and no coil compaction was observed.  The coil packing density seems to be one of the critical factors, particularly for predicting whether or not coil compaction will occur. Endovascular surgery should be performed to obtain coil packing density higher than 20%.     

Histologic and hemodynamic effects of endosaccular platinum coils for intracranial aneurysms

Over the past 15 years, endosaccular platinum coil therapy for intracranial aneurysms has evolved from clinical pilot studies of investigational devices to common clinical practice. The mechanism by which these coils reduce the risk of aneurysm rupture-the primary goal of intracranial aneurysm treatment-is the focus of this review. Both histological mechanisms of scar formation and hemodynamic mechanisms of flow diversion may be involved. We will first review aneurysm epidemiology to provide the context and rationale for therapy for patients harboring intracranial aneurysms. Next, we will review the data for and theories of the pathophysiology of aneurysm formation, growth, and rupture, particularly as they relate to endovascular coil therapy. Histological and hemodynamic studies of coiled aneurysms in animals and humans will be reviewed. Finally, we will discuss emerging coil-based therapies, such as bioactive polymer coatings for platinum coils and the adjunctive use of stents.     

WingSpan Stent System in the endovascular treatment of intracranial aneurysms: clinical experience with midterm follow-up results

OBJECT: The WingSpan stent is a new self-expandable neurovascular stent designed for endovascular treatment of intracranial atheromatous lesions. The authors report their experience with the use of this stent for the endovascular treatment of intracranial aneurysms. METHODS: Thirty-seven patients with 40 wide-necked intracranial aneurysms were treated using the WingSpan stent. Twenty-two aneurysms (55%) were small and 18 (45%) were large or giant. In all but 4 aneurysms, embolization was completed by packing the aneurysm sac with platinum coils. In 4 dissecting aneurysms that were fusiform or too small and wide necked to be catheterized, the stent was used alone. In these cases, the stent bridged the aneurysm neck to allow for flow redirection and the potential stent-induced endothelization effect. RESULTS: Follow-up angiograms obtained in 3 of 4 aneurysms, treated with only stent placement, demonstrated aneurysmal thrombosis and parent artery remodeling in 2 patients and moderate decrease in size in 1. Follow-up angiography obtained at 6 months to 1 year in 31 aneurysms after stent-supported coil embolization demonstrated complete occlusion in 23 aneurysms (74.2%) with a progressive thrombosis rate of 66.7% (10 of 15 aneurysms), and a recanalization rate of 16.1%. CONCLUSIONS: In treating wide-necked intracranial aneurysms, the WingSpan Stent System is very flexible, secure, and effective. Its delivery system is very easy and exact in that it exerts higher outward radial force, thus providing an excellent conformability and a strong scaffold to hold the coils in place. It may offer an effective treatment when used alone in some fusiform or very wide-necked, small dissecting aneurysms in which other surgical or endovascular treatment strategies are not deemed feasible.     

Balloon-assisted coil placement in wide-necked cerebral aneurysms: preliminary clinical experience

Endovascular treatment of wide-necked cerebral aneurysms with Guglielmi detachable coils (GDCs) has been limited due to coil protrusion into the artery. Seven patients with wide-necked cerebral aneurysms were treated with GDCs with temporary balloon inflation for mechanical protection during coil placement. Transarterial embolization of the aneurysm with GDCs had failed due to coil protrusion into the parent artery. The use of simultaneous temporary balloon protection achieved more dense intra-aneurysmal coil packing, especially in the neck, without compromising the parent artery.     

Packing efficacy of hydrocoil embolic system: in vitro study using ruptured aneurysm model

After endovascular coil embolization of cerebral aneurysms, coil compaction and late aneurysm recanalization have been ever observed. The HydroCoil Embolic System (HES) was developed to improve the packing efficacy of endovascular treatment of cerebral aneurysms. In this study, we evaluate the packing efficacy of HES using a silicone model of ruptured cerebral aneurysm. This silicone model was connected to a pulsatile flow pump and embolized with the initial framing coils followed by hydro coils (n = 3) or bare platinum coils (n = 3). The coils used in the two groups were identical to each other in size and length. In the hydro coil group, continuous outflow from ruptured aneurysm ceased in two out of three cases. On the other hand, in the bare platinum coil group, outflow from the ruptured point slightly decreased but did not stop in all cases. The hydro coil could result in a higher initial occlusion rate of silicone model. In addition, expanded hydrogel possibly sealed the ruptured point directly. Changes in the size of aneurysms were not detected, from which the risk of over-expansion seemed extremely low. The hydro Coil is a safe and feasible device for improving the packing efficacy in endovascular coil embolization.     

A loose-packing approach for coil embolization of giant intracranial aneurysm

Endoluminal occlusion of giant intracranial aneurysms with coil embolization is a viable endovascular treatment option alternative to surgical clipping. However, due to the relatively large aneurysm size, the use of embolization coils for giant aneurysms could be great. A loose-packing embolization strategy in which the fundus of the aneurysm is loosely packed while the aneurysm base is tightly packed is presented. Such a coiling strategy is best suited to giant aneurysms of elongated configuration and narrow neck as illustrated in the present case. While the use of the loose-packing approach is recommended for elongated aneurysms with a narrow neck, its use is not to be generalized for aneurysms of other configurations.     

Endovascular treatment of basilar artery aneurysms

International experience regarding the treatment of basilar artery aneurysms using the Guglielmi Detachable Coil (GDC) system was reviewed. The four patient series included in this critique were composed of similar numbers of patients who had aneurysms that predominantly involved the basilar artery bifurcation and who presented clinically after a subarachnoid hemorrhage. Consistent results observed between the individual outcome experiences were as follows: (1) complication rates associated with the endovascular treatment of basilar artery aneurysms compared favorably with the historical rates associated with direct surgical clipping; (2) smaller aneurysms in this location could be more safely and completely occluded than their larger counterparts; (3) the endosaccular thrombus produced after GDC placement is a dynamic, rather than permanent, entity; (4) progressive thrombosis, thrombolysis, or compaction of the coil mass — singly or in combination — can account for changes in the extent of aneurysm occlusion observed over time; (5) even if an aneurysm could not be obliterated completely, treatment with GDC coils immediately after subarachnoid hemorrhage appeared to confer a protective effect upon patients compared to the natural history of untreated, ruptured intracranial aneurysms. In summary, these studies support the following conclusions regarding GDC-mediated electrothrombosis for the treatment of aneurysms: (1) aneurysm morphologies that are the most troublesome to treat by a conventional open surgical approach are also the most difficult to treat endovascularly; (2) although a useful therapeutic option for high-risk surgical candidates after aneurysmal hemorrhages, the endovascular treatment of intracranial aneurysms (basilar or otherwise) as more than a temporizing (i.e., not curative) intervention is not yet supported by data; (3) when comparing the complications and expenses associated with open surgical and endovascular therapy for aneurysms, long-term morbidity and cost analyses must incorporate the respective requirements for subsequent angiographic evaluation and repeat treatment sessions to address aneurysm residuals; (4) limited clinical and angiographic follow-up data preclude conclusions regarding the value of endovascular treatment for the management of asymptomatic aneurysms; (5) direct clip ligation of intracranial aneurysms remains the definitive treatment strategy until appropriate prospective, controlled, randomized studies prove otherwise.     

Balloon assisted treatment of intracranial aneurysms: the conglomerate coil mass technique

Endovascular techniques for the treatment of intracranial aneurysms have rapidly evolved over the past 15 years since the introduction and subsequent US Food and Drug administration approval of the Gugleilmi detachable coil. During this period, a number of different coil designs and adjunctive devices have been developed to facilitate the treatment of more complex and challenging cerebral aneurysms. One such adjunctive device, the hypercompliant occlusion balloon, can be temporarily inflated during the delivery of embolization coils to prevent their prolapse into the parent vessel. This technique, known as balloon assisted treatment (BAT), remains somewhat controversial as many operators do not incorporate this approach into their practice, favoring stent supported techniques instead. Moreover, those operators who do practice BAT use a variety of different approaches. In this review, we discuss the theoretical concepts underlying BAT, the potential advantages and disadvantages of this approach and finally the technical evolution of BAT in our endovascular practice.     

Ruptured intracranial aneurysms associated with moyamoya disease: three case reports

Three cases of ruptured intracranial aneurysm associated with moyamoya disease are presented. Endovascular treatments were performed successfully in two patients with major artery aneurysms. One patient with a collateral aneurysm was managed conservatively and follow-up angiography 1 year later demonstrated spontaneous disappearance of the aneurysm. Our experience suggests that although aneurysms associated with moyamoya disease show differences in evolution and location, endovascular treatment of major artery aneurysms is safe and effective, and peripheral aneurysms which cannot be directly accessed for surgery or endovascular embolization may be treated conservatively.     

Stereotactic aspiration of enlarged intracerebral hematoma caused by intraprocedural perforation of aneurysm during coil embolization

BACKGROUND: Instead of surgical intervention, endovascular treatment with GDC has become an important tool to treat intracranial aneurysm in recent years. However, intraoperative aneurysm rupture remains a devastating complication for physicians. Rapid and precise packing with coils and external ventricular drainage are advised. Stereotactic aspiration of an enlarged intracerebral hematoma caused by intraprocedural perforation of aneurysm has been rarely discussed as a method of dealing with this consequence. CASE DESCRIPTION: The authors describe a case of a 45-year-old man who presented with sudden onset of headache. A ruptured aneurysm of approximately 5.5 mm, arising from the proximal segment of superior sylvian M2 branch on the right middle cerebral artery, was diagnosed via intracranial angiography. During transarterial embolization, perforation of the aneurysm dome by coil and microcatheter was noted. Although the aneurysm was secured by rapid coiling, progressive weakness of left extremities related to enlarged intracranial hematoma was noted. The neurologic deficits improved successfully after stereotactic aspiration of hematoma. CONCLUSION: The role of stereotactic aspiration in the management of an enlarged hematoma due to intraprocedural perforation of aneurysm during coil embolization may have further implications, and it may be considered as an alternative treatment to open clot evacuation for intracranial hemorrhages with aneurysms.     

Intrasaccular combination of metallic coils and onyx liquid embolic agent for the endovascular treatment of cerebral aneurysms

OBJECT: The aim of this study was to report on a novel technique in which metallic embolization coils were combined with the Onyx liquid embolic agent in the aneurysm sac to achieve a more durable result after endovascular treatment. This therapeutic procedure was performed in selected cases in which, based on the authors' experiences, either coil embolization or Onyx alone would likely have failed. The authors report long-term clinical and angiographic follow-up results in 20 consecutive intracranial aneurysms treated using this combination for defined indications. METHODS: Twenty aneurysms in 20 patients were treated with a combination of embolic coils and Onyx. Four aneurysms were giant; 13, large; and three, small. This new technique was used when standard Onyx or coil treatment with balloon assistance was determined to involve a higher possibility of recanalization, because either an adjunctive stent insertion could not be performed or the Onyx technique could not be used due to an unsuccessful seal test or intraaneurysm balloon prolapse. In one case, an adjunctive stent was placed before coil placement and Onyx deposition to control the material in the sac of the aneurysm, which had a fusiform neck. All aneurysms were completely occluded after using this technique. No clinical or technical adverse events occurred in any of the cases. Follow-up angiography was performed in all patients: 3-year studies in six patients, 2-year studies in five, and 1-year studies in nine. None of these studies demonstrated aneurysm regrowth or parent artery occlusion. CONCLUSIONS: The combination of the embolic coils and the Onyx liquid embolic agent provides very durable aneurysm occlusion for defined indications.     

Immediate and midterm follow-up results of using an electrodetachable, fully retrievable SOLO stent system in the endovascular coil occlusion of wide-necked cerebral aneurysms

OBJECT: Stent-assisted embolization is an alternative endovascular treatment method for wide-necked intracranial aneurysms. Currently available stents have the limitations of poor radial force, difficult delivery systems, and lack of full retrievability. The authors report on their preliminary experience with the use of a new, fully retrievable, self-expanding neurovascular stent, which has a high radial force and easy delivery system, combined with coil or Onyx embolization for the treatment of wide-necked aneurysms, including 6-month follow-up data. METHODS: Fifteen patients with 18 wide-necked intracranial aneurysms were treated using the SOLO stent system and detachable platinum coils. Aneurysms were located at the posterior communicating artery (seven lesions), midbasilar artery (one lesion), internal carotid artery (ICA) bifurcation (one lesion), ICA-ophthalmic artery segment (eight lesions), and posterior cerebral artery (one lesion). Eleven aneurysms were small, six were large, and one was giant. Only one of these aneurysms was in the acute stage of subarachnoid hemorrhage; balloon remodeling alone failed to keep the coils in the aneurysm sac. RESULTS: Only one stent required retrieving and repositioning after it had been fully deployed, and retrieval was easy and successful. No thromboembolic complication, dissection/rupture, or vasospasm occured during stent placement. Follow-up angiograms obtained at 6 months posttreatment in the 18 aneurysms demonstrated that all stents were patent with no evidence of intimal hyperplasia or stenosis. In all cases but one, 100% lesion occlusion was observed at the 6-month control angiography examination. Only one aneurysm had recanalized. CONCLUSIONS: The fully retrievable self-expandible SOLO stent is a feasible, secure, and effective system with a high radial force and ease of delivery in treating wide-necked intracranial aneurysms in combination with coil embolization.