Neuroform Stent Research Articles

Stent-assisted aneurysm coil embolization: safety and efficacy at a low-volume center

Background and purpose: To compare safety and efficacy of cerebral aneurysm embolization with and without Neuroform stent placement at a low procedural volume center.Methods: Retrospective cohort study of unruptured aneurysm coil embolization with and without Neuroform stent assistance over a period of 53 months at a center performing 14·4 interventions per year. Neuroform stent-assisted embolization was performed for 26 aneurysms in 25 patients (mean age: 61·3 years). Twelve patients (mean age: 64·3 years) with 12 unruptured aneurysms were treated without stent support. Comparative analysis of complications, angiographic findings, and clinical outcomes was performed.Results: Procedural complications for the Neuroform stent group was 7·69% (2/26) versus 8·34% (1/12) for aneurysms without (P=0·7; OR: 1·1; CI: 0·09-13·35).The Modified Rankin Scale (MRS) and Glasgow Outcome Scale (GOS) scores for all patients in the stent and non-stent groups were 0 and 5, respectively. Three out of 20 aneurysms (15%) were retreated for major recurrence in the stent group and two of 10 (20%) in the non-stent group (P=0·55; OR: 1·42; 95% CI: 0·20-10·23). At a mean follow-up of 16·9 months, persistent complete occlusion was observed in 36·8% (7/19) of aneurysms with stent support. At a mean of 15·9-month follow-up in 10 non-stented aneurysms, persistent complete occlusion was observed in 50% of aneurysms (P=0·69; OR=2·3; 95% CI: 0·38-14·2).Conclusion: Neuroform stent-assisted coil embolization at a low volume center is efficacious and does not increase procedural risk with optimal operator experience.

Comparison of Devices Used for Stent-Assisted Coiling of Intracranial Aneurysms

IntroductionTwo self-expandable stents, the Neuroform and the Enterprise stent, are widely used for stent-assisted coiling (SAC) of complex shaped intracranial aneurysms. However, comparative knowledge about technical feasibility, peri- and post-procedural morbidity and mortality, packing densities as well as follow-up data is limited.Material and MethodsWe conducted a retrospective study to investigate differences in aneurysms stented with the Enterprise or Neuroform stents. Angiographic follow-up (mean 19.42 months) was available in 72.6% (61/84) of aneurysms treated with stent-assisted coiling. We further sought to compare stent-assisted coiling to a matched patient population with aneurysms treated by conventional coil embolization.ResultsThe stenting success rate of the Enterprise was higher compared to the Neuroform stent (46/48 and 42/51, respectively). In 5 of 9 cases in which the Neuroform stent was not navigable to the landing zone, we successfully deployed an Enterprise stent instead. Eventually, 42 aneurysms were coiled after stenting in each group. We observed no significant differences in peri-procedural complication rate, post-procedural hospital stay, packing density, recurrence rate or number of in-stent stenosis. Strikingly, 36.1% of followed aneurysms in the SAC group showed progressive occlusion on angiographic follow-up imaging. The packing density was significantly higher in aneurysms treated by SAC as compared to conventionally coiled aneurysms, while recanalization rate was significantly lower in the SAC group.ConclusionThe procedural success rate is higher using the Enterprise, but otherwise both stents exhibited similar characteristics. Lower recurrence frequency and complication rates comparable to conventional coil embolization emphasize the importance of stent-assisted coiling in the treatment of complex aneurysms. Progressive occlusion on angiographic follow-up was a distinct and frequent observation in the SAC group and may in part be due to flow diversion.

Technical, angiographic and clinical outcomes of Neuroform 1, 2, 2 Treo and 3 devices in stent-assisted coiling of intracranial aneurysms

Background and purposeSince 2002 the Neuroform stent has expanded endovascular treatment of wide-necked intracranial aneurysms. A study was undertaken to assess the technical success rates and angiographic and clinical outcomes...

Bio-inspired leaf stent for direct treatment of cerebral aneurysms: design and finite element analysis

Cerebral aneurysm is common lesion among adult population. Current methods for treating the disease have several limitations. Inspired by fern leaves, we have developed a new stent, called leaf stent, which can provide a tailored coverage at the neck of an aneurysm and thus prevent the blood from entering the aneurysm. It alone can be used to treat the cerebral aneurysm and therefore overcomes problems existing in current treating methods. The paper focuses on the numerical simulation of the leaf stents. The mechanical behaviour of the stent in various designs has been investigated using the finite element method. It has been found that certain designs provide adequate radial force and have excellent longitudinal flexibility. The performance of certain leaf stents is comparable and even superior to those of the commercially available cerebral stents such as the Neuroform stent and the Enterprise stent, commonly used for stent assisted coiling, while at the same time, providing sufficient coverage to isolate the aneurysm without using coils.

E-021 Endovascular management strategies for anterior cerebral artery aneurysms: a single low volume center experience

PurposeTo evaluate management strategies, efficacy and clinical outcomes of anterior cerebral artery aneurysm endovascular treatment at a low volume community hospital.Material and MethodsProspective data entry and retrospective review of endovascular...

Improved delivery of the Neuroform 3 stent: technical note

BackgroundIntracranial stents have expanded endovascular therapy to wide neck aneurysms whose dimensions and configurations are not amendable to coil embolization alone. Stents however have not eliminated all problems due to...

Thromboembolic Complications After Neuroform Stent-Assisted Treatment of Cerebral Aneurysms: The Duke Cerebrovascular Center Experience in 235 Patients With 274 Stents

The Neuroform Stent has facilitated the endovascular treatment of wide-necked cerebral aneurysms. It is unknown which factors pose risks of thromboembolic events after stent placement. This series is the largest single-center study reporting on the incidence of and factors influencing thromboembolic complications after Neuroform stent placement. A total of 235 patients were treated with 274 Neuroform stents. The thromboembolic event rate was determined by imaging or clinical evidence of cerebrovascular accident within 90 days of stent placement; for patients with incomplete follow-up through chart review, telephone interviews were conducted. Analyses were performed to investigate patient factors that may be associated with stroke. Most aneurysms were unruptured; 30 patients (12.8%) presented with acute subarachnoid hemorrhage. Twelve patients of the 224 with follow-up (5.4%, 95% confidence interval: 2.4%-8.3%) demonstrated imaging or clinical evidence of a new thromboembolic event within 90 days of stent placement. There was a 3.1% thromboembolic rate for unruptured aneurysms and a 20% rate in patients with subarachnoid bleed. Hemorrhage was significantly associated with having a thromboembolic event (P = .002). There was a trend toward an increased thromboembolic event rate for patients with hypertension (P = .07). Larger stent caliber was significantly associated with a decreased thromboembolic event rate (P = .032). Our results suggest that the thromboembolic event rate associated with Neuroform stent use is low in unruptured aneurysms. In ruptured aneurysms, the complication rate is high, possibly partly related to restricted use of antiplatelet therapy. Stent size and hypertension may be associated with the risk of stroke, but additional studies are needed to confirm their significance.

Y-Stent-Assisted Coil Embolization of Wide-Neck Intracranial Aneurysms

This report evaluated the short and midterm results of the safety and effectiveness of the treatment technique with hybrid and non-hybrid Y-configured, dual stent-assisted coil embolization of wide-neck intracranial aneurysms, and reviewed the literature concerning this technique. Nine patients, eight with unruptured and one with ruptured aneurysms were included in the study. Of aneurysms embolized with a hybrid (with two different stents) and non-hybrid (with two identical stents) technique, three were located in the anterior communicating artery, three at the tip and one at the distal site of basilar artery, and two in the middle cerebral artery. All aneurysms included the orifices of bifurcation vessels. All aneurysms were stented and embolized during the same session. While Neuroform and Enterprise stents were used in the hybrid technique, two Enterprise stents were used in the non-hybrid technique. Dual Y-stent assisted coil embolization was performed successfully in eight of nine patients (88.9%), including five patients (55.6%) with hybrid and three patients (33.3%) with non-hybrid technique. No procedural complication, no mortality and no minor or major neurological complications were seen during the angiographic or clinical follow-up. When an attempt was made at passing the second stent through the first Enterprise stent, the stent protruded inside the aneurysm in one patient (11.1%). Hybrid or non-hybrid dual Y-stent-assisted coil embolization in the treatment of ruptured or unruptured wide-neck and complex intracranial aneurysms is a safe and effective method from the viewpoint of short and midterm results.

Neuroform Stent-Assisted Embolization of Incidental Anterior Communicating Artery Aneurysms: Long-term Clinical and Angiographic Follow-up

Anterior communicating artery (A-comm) aneurysm is one of the most common intracranial aneurysms. Treatments include neurosurgical clipping or endovascular embolization. To retrospectively examine the long-term results of Neuroform stent-assisted coil embolization of incidental A-comms, with a focus on stent-associated stenosis, long-term angiographic aneurysm occlusion outcome, delayed stent-related thromboembolus, subsequent subarachnoid hemorrhage from the treated aneurysm, and procedural complications. Between January 7, 2003 and June 16, 2009, 44 Neuroform stents were placed as an adjunct to embolization of A-comms. Patient charts were reviewed retrospectively. Angiographic follow-up of at least 3 months (up to 6.5 years, mean 65 weeks) was available for 33 patients. Aneurysm occlusion success was determined using the Raymond classification for aneurysm remnants. Referencing the last angiogram in the follow-up course, complete occlusion, dog-ear residual, residual neck, and residual aneurysm were found in 24, 2, 3, and 4 patients, respectively. Stenosis (45% and asymptomatic) of the artery where the stent had been placed was found in 1 patient. One patient had delayed transient ischemic attack after dual antiplatelet therapy was stopped prematurely. Retreatment based on the presence of residual aneurysm was performed or recommended in 2 patients. In 2 patients with residual or recurrent aneurysm filling, their age or clinical condition did not warrant retreatment. Neuroform stent-assisted embolization provides long-term control of A-comms with a low incidence of aneurysm growth after treatment. The need for retreatment is uncommon, and retreatment is safe if performed. Subsequent bleeding from treated aneurysms was not observed in this study.

Hemodynamic effect of Neuroform stent on intimal hyperplasia and thrombus formation in a carotid aneurysm

Stents play an important role in management of cerebral aneurysms. A stent reconstructs the parent artery, assists coil embolization, and decreases flow activity within an aneurysm. However, an in-stent stenosis often occurs within the stented artery and compromises the circulation at the parent artery. Hemodynamic basis of re-stenoses from aneurysm stenting is not fully understood. An 8 mm cavernous carotid aneurysm with a wide neck was treated by a Neuroform stent first and by coils five weeks later. A comparison of the difference in morphology during this five-week period reveals the presence of intimal hyperplasia in the internal carotid artery, 1.3 mm thick at the proximal end and 1 mm at the distal end of the stent, and 1 mm thick thrombus at the postero-inferior side of the aneurysm. Computational fluid dynamic analyses show that the site of intimal hyperplasia is exposed to low wall shear with high oscillatory shear index (OSI), and the location of thrombus is subject to high OSI. Intimal hyperplasia and thrombus occur at comparable rates, but at different hemodynamic conditions; however, both prefer regions with high OSIs.

Endovascular treatment of complex intracranial aneurysms using intra/extra-aneurysmal stent

Intra/extra-aneurysmal stent placement for treatment of complex and wide-necked bifurcation aneurysms has been previously described. However, this technique has been rarely reported in the treatment of dissecting aneurysms with incorporated vessels. We assess the feasibility and effectiveness of intra/extra-aneurysmal stent-assisted coil embolization in the treatment of those complex intracranial aneurysms. Between January 2009 and April 2010, nine consecutive patients with wide-necked or dissecting aneurysms with incorporated vessels underwent endovascular treatment using intra/extra-aneurysmal stent-assisted coiling at our institution. We assessed the clinical history, morphologic features of the aneurysms, treatment results, and follow-up. All Neuroform stents were successfully deployed in this series. Of the nine aneurysms treated with stent-assisted embolization, complete occlusion was achieved in seven aneurysms, nearly complete in one, and incomplete was present in one. There was no procedure-related complication in this series. Angiographic follow-up results of eight patients (mean, 8.6 months) showed continued obliteration of the aneurysms in six patients, incomplete occlusion in two patients, and the two patients received second treatment. On the modified Rankin Scale applied in follow-up, all patients were assessed as functionally improved or of stable clinical status. Intra/extra-aneurysmal stent placement and subsequent coil embolization may be effective for the treatment of selected patients with complex intracranial aneurysms. Short-term follow-up data indicate good durability of stent-assisted aneurysm occlusion. However, further study with longer follow-up and larger case series is necessary for validation of the efficacy of this treatment modality.

Treatment of acute ischemic stroke: feasibility of primary or secondary use of a self-expanding stent (Neuroform) during local intra-arterial thrombolysis

We evaluated the feasibility of employing a self-expanding stent (Neuroform) in treatment of acute cerebral ischemia and compared the results of primary and secondary stenting. We analyzed the treatment results of 14 acute ischemic stroke patients (11 men and three women; median age, 65years) who were treated with Neuroform stents. Seven patients received stent placement for primary recanalization and a further seven for secondary recanalization. We performed between-group comparisons of all of overall procedure duration, recanalization rate immediately after stenting, need for additional measures after stenting, final recanalization rate, occurrence of hemorrhagic transformation, early re-occlusion rate after 24h, and 3-month functional recovery rate (mRS ≤2). The median interval from femoral puncture to stent placement was 61.5min and was significantly shorter in the primary than in the secondary group (55 vs. 95min, p = 0.004). The recanalization rate immediately after stenting was 42.9% and was greater in the primary than in the secondary group (71.4% vs. 14.3%, p = 0.1). Thirteen patients required various additional therapeutic measures. The final recanalization rate was 78.6%, attributable to improvements in the recanalization rate of the secondary group (71.4% vs. 85.7%). Early hemorrhagic transformation was noted in four patients, but only one patient became symptomatic (symptomatic hemorrhage, 7.1%). Good functional recovery was noted in eight patients (57.1%). Placement of a self-expanding stent during endovascular recanalization of acute ischemic stroke was both feasible and safe. Primary use of this method may enhance early recanalization.

Thromboembolic events associated with endovascular treatment of cerebral aneurysms

ObjectiveTo evaluate the rate of peri-procedural thromboembolic events after the endovascular treatment of cerebral aneurysms. The rate of diffusion-positive lesions was assessed in relation to selected procedural and technical factors.Methods184...

Optimization of MR Parameters of 3D TOF-MRA for Various Intracranial Stents at 3.0T MRI

PurposeThe in-stent signal reduction of the stented artery caused by susceptibility artifact or radiofrequency shielding artifact limited the use of time-of-flight MR angiography (TOF-MRA) as a follow-up tool after intracranial stenting. We showed the degree of an artifact according to different stent types, and optimized MR parameters for TOF-MRA in patients with intracranial stent on 3.0 T MRI.Materials and MethodsFour stents (Neuroform, Wingspan, Solitaire, and Enterprise) were placed in a vascular flow phantom and imaged by changing flip angle (FA; 20°,30°,40°,50° and 60°) and bandwidth (BW; 31, 42 and 62.5 KHz) using TOF-MRA. Source data of each image set with different FA and BW were reconstructed with the maximal intensity projection (MIP) technique, and MIP images were used to evaluate the in-stent signal reduction of each stent according to the change of MR parameters. The in-stent signal reduction was assessed by calculating the relative in-stent signal (RIS) inside the stent as compared with background and signal intensity of the tube outside the stent. The optimal FA and BW of each stent were determined by comparing the RIS in each stent by one-sample t test. Finally, one neuroradiologist chose one image set with the best image quality.ResultsThe mean RIS for Neuroform, Wingspan, Solitaire and Enterprise stent was 66.3 ± 6.0, 44.2 ± 5.8, 22.8 ± 3.3 and 8.2 ± 2.9, respectively. The significantly high RIS of each stent was obtained with FA/BW value of 20°/31 KHz (Neuroform), 20°/31 KHz and 30°/42 KHz (Wingspan), 40°/42 KHz and 50°/31 KHz (Solitaire) and 40°/31 KHz and 50°/31 KHz (Enterprise). Among these MIP images with significantly high RIS, images with FA/BW value of 20°/31 KHz (Neuroform and Wingspan) and 50°/31 KHz (Solitaire and Enterprise) had the best image quality.ConclusionThe degree of artifact was variable according to the design of each intracranial stent. The luminal visualization of closed-cell design stents such as Solitaire and Enterprise can be improved by higher FA. Thus, MR parameter should be adjusted according to the type of intracranial stents.

Treatment of a Fusiform Vertebral Aneurysm with Double Stent Placement

A 34-year-old man admitted to another hospital presented with sudden onset of headache. The CT scan was unremarkable, but magnetic resonance angiography revealed a fusiform aneurysm in the left vertebral artery. Six days later, the patient was sent to our institution for further diagnosis and treatment. Cerebral angiography confirmed a fusiform aneurysm located in the right vertebral artery. At first, we placed a neuroform-3 stent and could see contrast medium stasis in the aneurysm, so we did not fill coils into the aneurysm. Four months later, the patient was admitted for rechecking. DSA showed the aneurysm remained and we placed a LEO stent in the lumen of the Neuroform stent. A control DSA eight months later showed the aneurysm had almost healed. Overlapping stents may induce spontaneous thrombosis of vertebral artery aneurysms and facilitate parent artery reconstruction through flow remodeling and stent endothelialization. This technique may be an option in treating dissecting or fusiform intracranial aneurysms that are not amenable to open surgical treatment or endovascular coil embolization.

Neuroform stent-assisted coiling of unruptured intracranial aneurysms: short- and midterm results from a single-center experience with 68 patients.

Intracranial stent placement assists in the coiling of wide-neck aneurysms and aids in reconstructing and protecting the parent artery. In this study, we analyze our experience in the use of the Neuroform system. Records of patients treated with a Neuroform stent from June 2003 to September 2007 were retrieved from a data base for analysis of population characteristics, occurrence of complications, and acute and midterm angiographic results. Sixty-eight patients harboring 76 aneurysms located primarily in the anterior circulation were treated. There were 5 cases (6.6%) of clot formation after deployment (1 with a permanent neurologic deficit), 1 case of perioperative stent displacement with hemorrhage, and 5 cases (6.6%) of transient neurologic deficit due to thromboembolic events. The morbidity-mortality rate at discharge was 2.9%. One patient presented with a delayed in-stent thrombosis, and 3 others, with silent stenosis. Twenty-four aneurysms (31.6%) were completely occluded in the initial embolization. However, a marked increase in the occlusion rate was observed, with 44 of the 68 aneurysms (64.7%) examined at the 18-month follow-up and 26 of the 46 aneurysms (56.5%) examined in the 3-year follow-up presenting with complete occlusion. At the end of the study, a neck remnant was present in 6 aneurysms (13%) and a residual sac, in 7 (15.2%). Mean follow-up time was 25.7 months. The present series demonstrates the relative safety and feasibility of the Neuroform stent-assisted coiling technique, which seems to provide better results over coiling alone for wide-neck aneurysms. Angiographic results improve with time due to progressive thrombosis of the aneurysm.

Progressive occlusion of aneurysms in Neuroform Stent-assisted treatment of intracranial aneurysms

IntroductionThe long term effect of Neuroform stent in progressive occlusion of intracranial aneurysms is not yet completely understood. Here the effect of the Neuroform stent in progressive occlusion of intracranial...

Neuroform stent-assisted coiling of intracranial aneurysms: a 5 year single-center experience and follow-up

Background and purpose: Wide-necked and fusiform aneurysms still remain a therapeutic challenge both surgically and endovascularly. The authors report their clinical experience and 5 year follow-up results using Neuroform stent, as an adjunct in the treatment of wide-necked and fusiform aneurysms.Methods: One hundred and seven consecutive patients with 110 wide-necked or fusiform intracranial aneurysms were treated with the Neuroform stent-assisted coiling. Both sequential technique and parallel technique were used. In all cases, embolization was completed by packing the aneurysm sac with a variety of commercially available coils. The technical feasibility of the procedure, procedure-related complications, angiographic results, clinical outcome and follow-up angiography were evaluated.Results: In every case, the Neuroform stent system was delivered and deployed accurately, and occlusion was achieved. Immediate angiography demonstrated complete occlusion in 57·2%, neck remnant in 27·3% and incomplete occlusion in 15·5%. Procedure-related morbidity was 5·6% and procedural-related mortality was 0·9%. Favorable clinical outcome (modified Rankin scale score: 0–2) was observed in 90·7% of the patients (average follow-up time: 47·3 months). No rehemorrhage of treated aneurysm occurred. Angiography follow-up was obtained in 45·8% (49/107 patients; 51/110 aneurysms; average follow-up time: 37·2 months). The overall recanalization rate was 13·7%. Comparison of occlusion class immediately after treatment and at last follow-up showed that 86·3% of the 51 aneurysms had stable or improved class. Eight aneurysms (36·4%) that were not initially completely occluded converted to complete occlusion on follow-up. No delayed coil or stent migration was found. One patient with in-stent stenosis and one with penetrating artery occlusion occurred as delayed complications.Conclusion: In treating complex intracranial aneurysms, the Neuroform stent-assisted coiling is a secure and effective technique.

Potential advantages and limitations of the Leo stent in endovascular treatment of complex cerebral aneurysms

Objective The Leo self-expandable stent is a new retractable stent that is delivered via a conventional catheter. The aim of this study was to evaluate the use of this stent for endovascular treatment of complex aneurysms. Methods Twenty-eight complex cerebral aneurysms (27 saccular and 1 fusiform) in 28 patients were treated electively. They were located at the internal carotid artery (17), basilar trunk (3), anterior cerebral artery (1), anterior communicating artery (3), vertebral artery (2) and middle cerebral artery (2). One aneurysm exhibited recanalization after primary endovascular treatment without stent. Clinical outcome was assessed with the modified Glasgow Outcome Scale. Results Deployment of Leo stent was successful in 26 lesions, and difficulties in stent positioning due to tortuous cerebral circulation in 2 cases, which were treated with Neuroform stent. Additional coil embolization was performed in 26 lesions. No permanent neurological deficits were encountered consequent to endovascular procedure. Complete or partial occlusion immediately after stent deployment was achieved in all aneurysms. There was no immediate coil embolization was chosen in 3 cases because of subsequent reduced filling of the aneurysms with contrast agent on angiograms. There were 3 asymptomatic parent artery occlusion related to the deployment of the Leo stent, one stent migration. Follow-up revealed patent stents in the remaining cases. No angiographic recurrences arose. Conclusion The Leo stent is very useful for endovascular treatment of complex cerebral aneurysms because it is easy to navigate and place precisely. A drawback is that in-stent thrombosis caused by stent placement and stiffer delivery catheters to place larger stents.

E-061 Safety and efficacy of Neuroform 3 for intracranial aneurysms treatment

ObjectivesTo assess the feasibility and the clinical performance of NF3 in intracranial aneurysms treatment. SENAT (Safety and Efficacy of Neuroform 3 for Intracranial Aneurysms Treatment) a multicenter registry, has been...