KIVILCIM YAVUZ, M.D., 1 SERDAR GEYIK, M.D., 1 ALMILA GULSUN PAMUK, M.D., 2 OSMAN KOC, M.D., 1 ISIL SAATCI, M.D., 1 AND H. SARUHAN CEKIRGE, M.D.

Transcription

1 J Neurosurg 107:49 55, 2007 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 KIVILCIM YAVUZ, M.D., 1 SERDAR GEYIK, M.D., 1 ALMILA GULSUN PAMUK, M.D., 2 OSMAN KOC, M.D., 1 ISIL SAATCI, M.D., 1 AND H. SARUHAN CEKIRGE, M.D. 1 Departments of 1 Radiology, and 2 Anesthesiology, Hacettepe University Hospitals, Ankara, Turkey 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. (DOI: /JNS-07/07/0049) KEY WORDS cerebral aneurysm coil embolization intracranial stent stent-assisted coil occlusion wide-necked aneurysm E Abbreviations used in this paper: BA = basilar artery; ICA = internal carotid artery; OphA = ophthalmic artery; PCoA = posterior communicating artery; VA = vertebral artery. NDOVASCULAR treatment, with its lower morbidity and mortality rates as shown in the recent multicenter International Subarachnoid Aneurysm Trial of endovascular coil occlusion compared with neurosurgical therapy, 24,26 has become increasingly preferred for intracranial aneurysms. Rapid technological advances in the field of endovascular treatment have allowed more complex lesions to be treated. Nonetheless, wide-neck aneurysms remain a therapeutic challenge with a much higher risk of recanalization, regrowth, and rerupture. 6,10,11 Recent endovascular strategies in the management of these lesions have included balloon remodeling, 27 the use of 3D coils, 9,21 the use of intravascular stents 17 combined with coils or Onyx liquid embolic agent to reconstruct the parent artery, 7,8, 22,25 and, most recently, the exclusion of cerebral aneurysms from the circulation using covered stents. 31 Initially, balloon-expandable coronary stents or specially developed balloon-expandable neurostents were used in the stent-assisted techniques. These devices had the disadvantage of poor flexibility and pushability, which often resulted in navigational difficulties in the tortuous cerebral circulation. In addition, the pressure-driven method of deployment increased the risk of damaging the artery and vessel rupture. Wanke and colleagues 34 reported on the initial clinical experience with a flexible, self-expanding neurovascular stent (Neuroform, Boston Scientific Co./Target), which represents a significant advance in the endovascular treatment of wide-necked aneurysms previously considered not amenable to such therapy. Several authors have documented the feasibility and safety of this device. 1,2,4,13,14,20 Nonetheless, limitations have also been reported, including a lack of retractability when partially deployed, low radial force, and some deployment difficulties. 2,4,5,14 Another self-expandable stent (Leo, Balt) has been shown to have some advantages over the Neuroform device because of its higher radial force, easier delivery system, and potential for repositioning when necessary. 19,28 In this report we describe the results of our initial clini- 49

2 K. Yavuz et al. cal experience with a new, fully retrievable, self-expanding neurovascular stent (SOLO, ev3 Inc.) combined with coils for the treatment of wide-necked aneurysms. Preclinical use of this stent has been detailed by Doerfler et al. 12 Clinical Material and Methods Patient Population and Study Criteria Fifteen patients (11 women and four men) with a mean age of years (range years) and harboring 18 wide-necked intracranial aneurysms were treated using the SOLO stent system. In all cases embolization was accomplished with detachable platinum coils. The protocol inclusion criteria consisted of a wide-necked intracranial saccular aneurysm characterized by a dome/neck ratio less than 2.0 and/or a neck length of 4 mm or more; a parent artery with a diameter between 1.5 and 5 mm; a patient age greater than 18 years; and provision of written informed consent. Exclusion criteria were a fusiform or other nonsaccular aneurysm, a neck diameter larger than 15 mm, pregnancy, and a contraindication to medication (heparin, clopidogrel, aspirin, or angiographic contrast agent). Aneurysm Characteristics Aneurysm sizes were classified as small ( 1 cm), large ( 1 cm and 2.5 cm), and giant ( 2.5 cm). Of the 18 aneurysms, 11 were small, six were large, and one was giant. Aneurysms were located at the PCoA (seven lesions), mid-ba (one lesion), ICA bifurcation (one lesion), ICA OphA segment (eight lesions), and the P 1 segment (one lesion). Fourteen of the aneurysms were unruptured. Of the four ruptured lesions, three had ruptured more than one month before the treatment procedure. One of these aneurysms was wrapped surgically, a second was embolized with coils using a balloon remodeling technique but had recanalized, and a third was not treated after bleeding. Only one acutely ruptured aneurysm was treated using a SOLO stent (as described later). Three of the 18 aneurysms were recanalized lesions. Previous therapies consisted of coil placement in two cases and Onyx liquid embolic agent in one case. All 18 aneurysms were occluded using bare platinum detachable coils. Study Protocol According to the study protocol, all patients were premedicated with antiplatelet therapy consisting of 300 mg of aspirin and a loading dose of 300 to 450 mg of clopidogrel 1 to 7 days before the procedure. Clopidogrel (75 mg/day) was continued for an additional 30 days after the procedure and then stopped. Aspirin (300 mg/day) was continued and anticipated to be administered for the patient s lifetime. All patients received heparin with the goal of elevating the activated clotting time level two to three times compared with baseline during the procedure and for the following 24 hours. Given the necessity for sustained antiplatelet therapy and the potential for early rebleeding from ruptured lesions, unruptured aneurysms were preferred for treatment in this series. The study therefore included only one acutely ruptured aneurysm. This lesion had a mid-ba location, and the SOLO stent was used in combination with balloon placement within the stent. This method of therapy was selected when neither balloon remodeling nor stent insertion, when performed alone, could retain the coils within the aneurysm sac. The feasibility of delivery and deployment, radial force, visibility, ease of retrievability (if needed), ease of stent detachment, and aneurysm occlusion rate were documented. All patients underwent clinical and angiographic follow-up at 6 months posttreatment. The occlusion rate of the aneurysm, patency of the parent artery, evidence of intimal hyperplasia, and in-stent stenosis were noted on the follow-up angiograms. Stent System The SOLO stent is made of a laser-cut nitinol tube with a honeycomb pattern that is attached to a platinum marker coil (proximal coil). Its placement is controlled by the standard proximal and distal markers on the microcatheter, which are to be aligned with a 3-cm delivery coil at the end of the delivery system. A stainless-steel segment (detachment zone) is detached using direct current application (2 ma, 4 6 V, for seconds) for stent deployment. The stent can be visualized using three distal markers and the proximal coil segment that remains attached to it (Fig. 1). Technique of Stent Deployment and Endosaccular Coil Occlusion All procedures were performed under general anesthesia. A 6-F guiding catheter was introduced into the ICA for anterior circulation aneurysms and into the VA for posterior system lesions. A Rapid Transit (Cordis Neurovascular) or Rebar 18 (ev3 Inc.) microcatheter was advanced to bypass the aneurysm neck. The SOLO stent was then delivered via the microcatheter and deployed after positioning to bridge the aneurysm neck. Deployment was completed in a standard fashion by holding the stent pusher stationary while withdrawing the microcatheter. If its position was satisfactory, the stent was immediately electrically detached after deployment. All detachments took less than 1 minute. Another microcatheter was then placed in the aneurysm and coils were inserted. In the case of the ruptured mid-ba aneurysm in which balloon remodeling alone failed to keep the coils in the aneurysm sac, the microcatheter was withdrawn; the SOLO stent was deployed in the BA across the aneurysm neck but was not detached. Another 6-F guiding catheter was placed within the contralateral VA, and through this catheter a 4 7 mm Hyperform balloon (ev3 Inc.) was positioned within the stent. A microcatheter was placed in the aneurysm sac through the mesh of the stent. The aneurysm was then successfully filled with coils by using stent- and balloonassisted techniques, and detachment of the stent was accomplished after endosaccular coil occlusion (Fig. 2). In two patients, aneurysms located at the carotid artery termination or OphA segment of the ICA were initially coiled using balloon remodeling alone; the SOLO stent was then deployed in the parent artery. In these cases, stents were inserted to provide additional support in preventing the aneurysm regrowth that would be predicted given the large size of the lesions. Furthermore, the initial occlusion with coil embolization was not complete (Raymond Class 2) in the ophthalmic segment aneurysm. The ICA termina- 50

3 Stent-assisted coil occlusion of wide-necked cerebral aneurysms tion aneurysm was a regrown lesion and the stent was used in the retreatment even though complete occlusion was achieved with balloon-assisted coil embolization. 30 After obtaining control angiograms, the guide catheter and vascular sheath were withdrawn, and hemostasis was achieved using a vascular closure device. FIG. 1. Diagrams depicting the SOLO stent. A: Entire stent system. B: Stent in its deployed state. Radiopaque markers are shown as well. Microcath. = microcatheter; Prox. = proximal. Results All patients were successfully treated using this technique with no procedural or delayed complications. No thromboembolic complications, arterial dissections/ruptures, or spasms occurred during stent placement. The only patient treated in the acute stage of subarachnoid hemorrhage (Hunt and Hess Grade I at presentation) left the hospital with a good clinical status (Glasgow Outcome Scale Score 1). There were no difficulties in delivering the stents. In only FIG. 2. A and B: Initial diagnostic left VA angiogram, Towne and oblique projections, demonstrating a ruptured mid- BA wide-necked aneurysm and vasospasm of the BA. C: Nonsubtracted view showing deployed but not detached SOLO stent in the BA across the aneurysm neck. Three distal radiopaque markers are indicated by arrows. A 4 7 mm Hyperform balloon (arrowheads) was positioned within the stent from the contralateral VA. The aneurysm was then embolized with stent- and balloon-assisted coil insertion, and detachment of the stent was accomplished after endosaccular coil placement. D: Immediate posttreatment angiogram exhibiting complete occlusion of the aneurysm. E and F: Six-month follow-up angiograms, subtracted and nonsubtracted oblique views, revealing stable complete occlusion. 51

4 K. Yavuz et al. TABLE 1 Summary of relevant clinical and angiographic data and treatment strategies in 15 patients harboring aneurysms* Age Raymond Class Case (yrs), Aneurysm Aneurysm No. Sex Aneurysm Location Type Size Treatment Procedure Initial FU 1 46, F ICA OphA segment U S SOLO stent-assisted coil embolization 1 1 ICA OphA segment U S SOLO stent-assisted coil embolization , F PCoA U S SOLO stent-assisted coil embolization , F PCoA U L SOLO stent-assisted coil embolization , F PCoA R L SOLO stent insertion after balloon-assisted coil embolization , F ICA OphA segment U S SOLO stent-assisted coil embolization , M PCoA R L SOLO stent-assisted coil embolization , F P 1 segment U S SOLO stent-assisted coil embolization , F ICA bifurcation R L SOLO stent after balloon-assisted coil embolization , F mid-ba R S balloon-in-stent assisted coil embolization , M ICA OphA segment U L SOLO stent-assisted coil embolization , F PCoA U L SOLO stent-assisted coil embolization , M PCoA U S SOLO stent-assisted coil embolization 2 1 ICA OphA segment U S SOLO stent-assisted coil embolization , F ICA OphA segment U G SOLO stent-assisted coil embolization , F PCoA U S SOLO stent-assisted coil embolization , M ICA OphA segment U S SOLO stent-assisted coil embolization 2 1 ICA OphA segment U S SOLO stent-assisted coil embolization 2 1 * FU = follow-up; G = giant; L = large; R = ruptured; S = small; U = unruptured. Two patients with 1-year follow-up results. The patient who was treated in the acute phase of subarachnoid hemorrhage. one case was it necessary to retrieve and reposition the stent after its initial full deployment; stent retrieval was easy and successful. The radiopacity of the three distal and one proximal marker, which promoted proper placement of the stent, was satisfactory. A 10 or 18 microcatheter was easily navigated through the stent struts into the aneurysm sac in all cases in which the stent was placed prior to coil embolization. Based on the postembolization angiography studies, total occlusion with no residual lumen filling (Raymond Class 1) was achieved in 10 of 18 aneurysms. In the remaining eight aneurysms, there was more than 95% occlusion (Raymond Class 2) but minimal residual filling with coils at the aneurysm neck in six, and less than 95% occlusion in two (Raymond Class 3). No stent misplacement or dislodgement occurred during the procedure (Table 1). Six-month follow-up angiograms of all aneurysms and 1-year follow-up angiograms of two ICA aneurysms were obtained. The last follow-up findings on the 18 aneurysms showed all stents to be patent with no evidence of intimal hyperplasia or stenosis. Seventeen of the 18 aneurysms demonstrated 100% occlusion at this time. In seven of eight aneurysms that had shown Raymond Class 2 or 3 occlusion on the immediate postembolization angiographies, the 6-month control angiography studies revealed progressive thrombosis of the sacs resulting in complete obliteration (Fig. 3). The only regrowth observed at the 6-month follow-up consisted of a large ICA posterior wall aneurysm for which there had been Raymond Class 2 occlusion on the immediate postembolization angiogram (Fig. 4). Discussion Endosaccular embolization of wide-necked, complex, and large or giant aneurysms with preservation of the parent artery remains a challenge for the neurointerventionalist. To avoid coil protrusion or migration into the parent artery and subtotal occlusion leading to recanalization or regrowth, advanced endovascular techniques/products including balloon remodeling, 27 different coil designs (for example, 3D coils), 9,21 and liquid embolic agents 8,22,25 have been developed. The efficacy of bioactive coils remains controversial and is being studied in randomized trials. The application of an endovascular stent seems to provide several important theoretical and technical advantages. The stent not only supports aneurysm packing and produces flow redirection, but also provides a physical matrix for endothelial regrowth. 14,22 Thus, stent insertion treats not only the aneurysm, but also the diseased parent vessel. The stents initially used in the intracranial circulation were a variety of stainless-steel, balloon-expandible peripheral or coronary stents 3,17,18,23,29,33 and stent grafts, 31 which were followed by more flexible, self-expanding stents that are easier to navigate in the intracranial vessels specifically designed for neurovasculature use. The Neuroform stent (Boston Scientific) was the first commercially available self-expanding microstent specifically designed for the treatment of broad-based aneurysms. This stent is constructed of nitinol, with diameters ranging from 2.5 to 4.5 mm. Regarding this first-generation stent system, the radiolucency of the stent mesh, which is not visible even under high-quality fluoroscopy, together with the open-cell design can cause prolapse of the stent struts into the aneurysm; and thus, it can be very difficult to judge whether a coil loop is on the luminal or aneurysm side of the stent. The low radial force of the stent can be advantageous in reducing injury to the vessel wall, but can also allow displacement of the stent after its deployment. Moreover, the stent lacked retrievability after inaccurate deployment. Several technical problems with stent delivery have been described in the literature, 5,14 including misplacement of the stent into the target aneurysm or dislodgement dur- 52

5 Stent-assisted coil occlusion of wide-necked cerebral aneurysms FIG. 3. Initial diagnostic angiogram (A) and 3D reconstruction image (B) showing a wide-necked bilobulated ICA aneurysm. Posttreatment angiogram (C) demonstrates more than 95% (Raymond Class 2) occlusion of the aneurysm. Another posttreatment angiogram (D), nonsubtracted view, reveals the endosaccular coil pack with the stent at the neck. Arrows indicate radiopaque markers. Six-month follow-up angiogram (E) showing progressive thrombosis of the aneurysm sac resulting in complete obliteration (Raymond Class 1). ing catheterization. After structural revisions to improve delivery characteristics, the Neuroform2 Treo was then introduced, 32 and Fiorella et al. 13 reported a few technical problems with stent delivery and deployment in one of the largest studies of this system. Recently, the preassembled Neuroform3 stent with its closed-cell design was introduced, providing greater scaffolding for coil mass support and sufficient radial force to generate stability within the vessel. Clinical studies are required to determine the safety and efficacy of this new design. Another self-expanding stent, the Leo (Balt), made of braided nitinol wires, has a design combining higher radial force and ease of delivery with the advantage of repositioning the stent when necessary. There are two highly radiopaque wires that ensure visibility of both their diameter and length. Available stent diameters and lengths range from 2.5 to 7.5 mm and 12 to 95 mm, respectively. The Leo stent has overlapping struts with a mesh tighter than that of the Neuroform stent. The major advantage of the Leo delivery system is an innovative distal hook that allows resheathing and repositioning of the stent when it is as much as 90% deployed. In our experience, however, the system easily detaches when retrieval is attempted. Preliminary experiences with the Leo stent 19,28 have indicated that the stent delivery system could be navigated successfully in all cases. One potential disadvantage of the Leo stent compared with the Neuroform stent is the need for progressively larger microcatheters to deliver the larger Leo stent devices 19 if the vessel is 4 mm or larger. The SOLO stent differs from other commercially available stents in many respects. It can be deployed through 18 microcatheters, such as the Rapid Transit or Rebar 18. Pushing the stents through these 18 microcatheters was comparable to pushing 18 coils. This feature together with the SOLO stent s excellent flexibility allows it to reach intracranial locations very easily. Furthermore, this stent can be retrieved and repositioned even after full deployment. It has a closed-cell design cut from a nitinol tube together 53

6 K. Yavuz et al. FIG. 4. A: Pretreatment lateral carotid artery angiogram showing a broad-necked ICA aneurysm. B and C: Nonsubtracted and subtracted, respectively, angiograms demonstrating Raymond Class 2 aneurysm occlusion with coils and the stent across the neck. Proximal and distal markers of the stent are indicated by arrows in panel B. D: Six-month follow-up angiogram displaying regrowth of the aneurysm at the neck. with a nitinol pusher wire. The closed-strut design addresses problems that can result from the dislocation of single cells in an open-strut mesh or from interference with coils and guidewires. 16 It holds coils in the aneurysm sac very effectively. The stent has satisfactory visibility through the three distal markers and the proximal coil segment that remains attached to it, and placement is controlled by these markers on the microcatheter that are to be aligned with the 3-cm delivery coil at the end of the delivery system. The stainless-steel segment (detachment zone) is detached by direct current application for stent deployment. Available stent diameters and lengths for this series were limited, ranging from 3 to 4 mm in diameter and 10 to 20 mm in length. In the present series, we used the SOLO microstent without technical difficulty in 15 patients with 18 wide-necked aneurysms; the stent could be easily delivered through the microcatheter and positioned to bridge the aneurysm neck in all cases. The stent was repositioned after having been fully deployed in one particular case with no difficulty. The detachment was reliable and quick, averaging around 30 seconds. The higher radial force in this stent reduces the possibility of displacement after deployment. In all cases placement of the microcatheter through the stent into the aneurysm was achieved without any difficulty. Withdrawal of the microcatheter at the end of coil insertion was uneventful. The radial force and closed-cell design of the stent allowed excellent stabilization of coils between the stent and parent artery and prevented possible thromboembolic events. In our opinion, one of the major advantages of the SOLO stent system is the ability to deploy the stent and safely place a remodeling balloon within it to perform stent- and balloon-assisted coil insertion or treatment with the Onyx embolic agent without detaching the stent (Fig. 2). The stent can be detached after the treatment is completed. This technique eliminates the risk of stent malposition if balloon placement is needed in the stent immediately after its deployment. This approach can be applied using a larger inner-bore single 6-F guide sheath (6F Destination; Terumo, Inc.) or double guiding catheters. With the use of antiplatelet therapy, which is routinely initiated 1 to 7 days before the procedure, neither immediate nor late thromboembolic complications occurred in the present study. Furthermore, contrary to the recent data reported by Fiorella et al., 15 no in-stent stenosis was observed. The overall total occlusion rate was 56% (10 of 18) immediately after treatment with SOLO stent supported coil embolization. Note, however, that follow-up angiography demonstrated noteworthy progressive occlusion in seven (87.5%) of the eight remaining aneurysms with initial Raymond Class 2 or 3 occlusion at the end of treatment, resulting in an overall total occlusion rate of 94.4% (17 of 18) at 6 months. These rates compare favorably with the those of Fiorella et al., 13 who reported a progressive occlusion rate of 52.1 % in their study of a Neuroform stent and coil combination. Conclusions Our preliminary experience shows that the fully retrievable, self-expandible SOLO stent in combination with coil embolization is a feasible, secure, and effective system with a higher radial force and ease of delivery in treating wide-necked intracranial aneurysms. The main advantages of the SOLO stent include its delivery system via a standard 18 microcatheter, which is as easy as delivering an 18 metallic coil, and its retrievability even after full deployment. Although very durable aneurysm occlusion with 100% stent patency was observed on the 6-month follow-up angiograms in the present study, larger series with longer-term follow-ups are required. Disclosure Drs. Saruhan Cekirge and Isil Saatci conduct research and provide clinical medical services, teaching, and training with regard to their original scientific research for ev3 Inc. References 1. Akpek S, Arat A, Morsi H, Klucznick RP, Strother CM, Mawad 54

7 Stent-assisted coil occlusion of wide-necked cerebral aneurysms ME: Self-expandable stent-assisted coiling of wide-necked intracranial aneurysms: a single-center experience. AJNR Am J Neuroradiol 26: , Alfke K, Straube T, Dörner L, Mehdorn M, Jansen O: Treatment of intracranial broad-neck aneurysms with a new self-expanding stent and coil embolization. AJNR Am J Neuroradiol 25: , Barras CD, Myers KA: Nitinol its use in vascular surgery and other applications. Eur J Vasc Endovasc Surg 19: , Benitez RP, Silva MT, Klem J, Veznedaroglu E, Rosenwasser RH: Endovascular occlusion of wide-necked aneurysms with a new intracranial microstent (Neuroform) and datachable coils. Neurosurgery 54: , Broadbent LP, Moran CJ, Cross DT III, Derdeyn CP: Management of neuroform stent dislodgement and misplacement. AJNR Am J Neuroradiol 24: , Byrne JV, Sohn MJ, Molyneux AJ, Chir B: Five-year experience in using coil embolization for ruptured intracranial aneurysms: outcomes and incidence of late rebleeding. J Neurosurg 90: , Cekirge HS, Saatci I, Geyik S, Yavuz K, Ozturk H, Pamuk G: Intrasaccular combination of metallic coils and onyx liquid embolic agent for the endovascular treatment of cerebral aneurysms. J Neurosurg 105: , Cekirge HS, Saatci I, Ozturk MH, Cil B, Arat A, Mawad M, et al: Late angiographic and clinical follow-up results of 100 consecutive aneurysms treated with Onyx reconstruction: largest singlecenter experience. Neuroradiology 48: , Cloft HJ, Joseph GJ, Tong FC, Goldstein JH, Dion JE: Use of three-dimensional Guglielmi detachable coils in the treatment of wide-necked cerebral aneurysms. AJNR Am J Neuroradiol 21: , Cognard C, Weill A, Spelle L, Piotin M, Castaings L, Rey A, et al: Long-term angiographic follow-up of 169 intracranial berry aneurysms occluded with detachable coils. Radiology 212: , Debrun GM, Aletich VA, Kehrli P, Misra M, Ausman JI, Charbel F: Selection of cerebral aneurysms for treatment using Guglielmi detachable coils: the preliminary University of Illinois at Chicago experience. Neurosurgery 43: , Doerfler A, Becker WP, Wanke I, Goericke SL, Mueller KM, Blechschmid N, et al: A novel flexible, retrievable endovascular stent system for small-vessel anatomy: preliminary ın vivo data. AJNR Am J Neuroradiol 26: , Fiorella D, Albuquerque FC, Deshmukh VR, McDougall CG: Usefulness of the Neuroform stent for the treatment of cerebral aneurysms: results at initial (3 6-mo) follow-up. Neurosurgery 56: , Fiorella D, Albuquerque FC, Han P, McDougall CG: Preliminary experience using the Neuroform stent for the treatment of cerebral aneurysms. Neurosurgery 54:6 17, Fiorella D, Albuquerque FC, Woo H, Rasmussen PA, Masaryk TJ, McDougall CG: Neurofrom in-stent stenosis: incidence, natural history, and treatment strategies. Neurosurgery 59:34 42, Henkes H, Kirsch M, Mariushi W, Miloslavski E, Brew S, Kuhne D: Coil treatment of a fusiform upper basilar trunk aneurysm with a combination of kissing neuroform stents, TriSpan-, 3D- and fibered coils, and permanent implantation of the microguidewires. Neuroradiology 46: , Higashida RT, Smith W, Gress D, Urwin R, Dowd CF, Balousek PA, et al: Intravascular stent and endovascular coil placement for a ruptured fusiform aneurysm of the basilar artery. Case report and review of the literature. J Neurosurg 87: , Lownie SP, Pelz DM, Fox AJ: Endovascular therapy of a large vertebral artery aneurysm using stent and coils. Can J Neurol Sci 27: , Lubicz B, Leclerc X, Levivier M, Brotchi J, Pruvo JP, Lejeune JP, et al: Retractable self-expandable stent for endovascular treatment of wide-necked intracranial aneurysms: preliminary experience. Neurosurgery 58: , Lylyk P, Ferrario A, Pasbon B, Miranda C, Doroszuk G: Buenos Aires experience with the Neuroform self-expanding stent for the tretment of intracranial aneurysms. J Neurosurg 102: , Malek AM, Higashida RT, Phatouros CC, Dowd CF, Halbach VV: Treatment of an intracranial aneurysm using a new threedimensional-shape Guglielmi detachable coil: technical case report. Neurosurgery 44: , Mawad ME, Cekirge S, Ciceri E, Saatci I: Endovascular treatment of giant and large intracranial aneurysms by using a combination of stent placement and liquid polymer injection. J Neurosurg 96: , Mericle RA, Lanzino G, Wakhloo AK, Guterman LR, Hopkins LN: Stenting and secondary coiling of intracranial internal carotid artery aneurysm: technical case report. Neurosurgery 43: , Molyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, et al: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomized trial. Lancet 360: , Molyneux AJ, Cekirge S, Saatci I, Gal G: Cerebral Aneurysm Multicenter European Onyx (CAMEO) trial: results of a prospective observational study in 20 European centers. AJNR Am J Neuroradiol 25:39 51, Molyneux AJ, Kerr RSC, Yu LM, Clarke M, Sneade M, Yarnold JA, et al: International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet 366: , Moret J, Cognard C, Weill A, Castaings L, Rey A: [Reconstruction technic in the treatment of wide-neck intracranial aneurysms. Long-term angiographic and clinical results. Apropos of 56 cases.] J Neuroradiol 24:30 44, 1997 (Fr) 28. Pumar JM, Blanco M, Vazquez F, Castineira JA, Guimaraens L, Garcia-Allut A: Preliminary experience with Leo self-expanding stent for the treatment of intracranial aneurysms. AJNR Am J Neuroradiol 26: , Raymond J, Roy D: Safety and efficacy of endovascular treatment of acutely ruptured aneurysms. Neurosurgery 41: , Roy D, Milot G, Raymond J: Endovascular treatment of unruptured aneurysms. Stroke 32: , Saatci I, Cekirge HS, Ozturk MH, Arat A, Ergungor F, Sekerci Z, et al: Treatment of internal carotid artery aneurysms with a covered stent: experience in 24 patients with mid-term follow-up results. AJNR Am J Neuroradiol 25: , Sani S, Jobe KW, Lopes DK: Treatment of wide-necked cerebral aneurysms with the Neuroform2 Treo stent. A prospective 6-month study. Neurosurg Focus 18(2):E4, Sekhon LH, Morgan MK, Sorby W, Grinnell V: Combined endovascular stent implantation and endosaccular coil placement for the treatment of a wide-necked vertebral artery aneurysm: technical case report. Neurosurgery 43: , Wanke I, Doerfler A, Schoch B, Stolke D, Forsting M: Treatment of wide-necked intracranial aneurysms with a self-expanding stent system: initial clinical experience. AJNR Am J Neuroradiol 24: , 2003 Manuscript submitted July 12, Accepted January 3, Address reprint requests to: H. Saruhan Cekirge, M.D., Department of Radiology, Hacettepe University Hospitals, Sihhiye, Ankara, Turkey. cekirgesaatci@superonline.com. 55