Stents for intracranial wide-necked aneurysms: more than mechanical protection

Immediate and midterm results following treatment of unruptured intracranial aneurysms with the pipeline embolization device

BACKGROUND AND PURPOSE

A number of flow-diverting devices have become available for endovascular occlusion of cerebral aneurysms. This article reports immediate and midterm results in treating unruptured aneurysms with the PED.

MATERIALS AND METHODS

A prospective registry was established at 3 Australian neurointerventional units. Aneurysms were treated on the basis of unfavorable anatomy or recurrence following previous treatment. Aneurysms were treated with PED or PED and coils. Data including antiplatelet therapy, technical issues, complications, and imaging findings were recorded during at least a 6-month period.

RESULTS

A total of 57 aneurysms in 54 patients were treated by 5 neurointerventional radiologists. Forty-one aneurysms were asymptomatic, and 16 patients had mass-induced neurological deficit. Clinical follow-up was available in 57 aneurysms with imaging follow-up at 6 months in 56. Permanent morbidity and mortality in the series was 0% at 6 months. Four TIAs and 1 small retinal branch occlusion occurred, but no stroke. The demonstrated aneurysm occlusion rate at 1 month was 61.9%, and the overall occlusion rate at 6 months was 85.7%. In cases previously untreated, the 6-month occlusion was 92.5%. Three of 6 aneurysms with a previous stent in situ were occluded. Two patients (3.5%) had asymptomatic in-construct stenosis of >50%. Acute aneurysm-provoked mass effect resolved or improved significantly in all cases.

CONCLUSIONS

Use of the PED is safe and efficacious in difficult aneurysms with a high occlusion rate at 6 months, but lower occlusion rates were seen in a small population with previous stents in situ.

Comparison of 2-year angiographic outcomes of stent- and nonstent-assisted coil embolization in unruptured aneurysms with an unfavorable configuration for coiling

BACKGROUND AND PURPOSE

Stents are known to have hemodynamic and biologic effects in addition to their mechanical scaffold effect. To determine whether stents affect long-term outcomes after coiling of unruptured aneurysms, we compared angiographic outcomes at 2 years postembolization for stent- and nonstent-assisted coiled unruptured aneurysms.

MATERIALS AND METHODS

Stent-assisted coiling was used in unruptured aneurysms unfavorable for simple coiling (neck size >4 mm and dome-to-neck ratio <1.5) in our practice. Therefore, 126 coiled unruptured aneurysms in total (40 [31.7%] stent group and 86 [68.3%] nonstent group) with these conditions were selected for this study. The nonstent group aneurysms were treated with multiple microcatheter technique (53 cases) or balloon-assisted technique (33 cases). Self-expandable stents were used for coiling in stent group aneurysms. No significant difference in aneurysmal characteristics (aneurysm type [sidewall/bifurcation], diameter, neck size, and dome-to-neck ratio) or angiographic outcome at embolization (packing attenuation, obliteration grade, and contrast filling) were observed between the 2 study groups.

RESULTS

At 2-year follow-up visits, rates of progressive occlusion (stent group, 17/40 [42.5%] versus nonstent group, 34/86 [39.5%]) and recanalization (7/40 [17.5%] versus 18/86 [21.0%]) did not show a statistically significant difference between the 2 groups (P = .895).

CONCLUSIONS

The present study did not show that additional hemodynamic and biologic effects of stents designed for neck remodeling were enough to enhance progressive occlusion and prevent the recanalization of unruptured aneurysms. Our finding suggests that stent placement provides no better long-term angiographic outcomes for unruptured aneurysms with an unfavorable configuration for coiling.

Aneurysm ostium angle: a predictor of the need for stent as assistance for endovascular aneurysm coiling in internal carotid artery sidewall aneurysms

BACKGROUND AND PURPOSE

There is no satisfactory parameter that can predict the need for assistant devices for endovascular aneurysm coiling. Our aim was to evaluate the utility of MOA as a predictor of the need for stent-assisted coiling in ICA sidewall aneurysms.

MATERIALS AND METHODS

From a retrospective review of an internal data base, 55 consecutive ICA sidewall aneurysms were identified. Thirty-two of the aneurysms were treated by using endovascular techniques. Because 23 of the 55 aneurysms were either untreated or clipped, 3 experienced interventionalists reviewed the 3D images of these aneurysms and then made a decision as to whether stent-assisted coiling would have been required. Thirty-one of the 55 aneurysms would have required stent-assisted coiling, while 24 would not. Neck width, DNR, AR, and MOA were obtained from each aneurysm by using prototype software. These parameters were then correlated with the requirement of stent-assisted coiling.

RESULTS

MOA and neck width of aneurysms requiring stent-assisted coiling were significantly larger than those not requiring stent-assisted coiling (P < .001 and <0.001, respectively). Although the DNR and AR of aneurysms requiring stent-assisted coiling were smaller than those not requiring it, the difference was not significant (P = .22 and 0.12, respectively). ROC analysis revealed that MOA was the parameter that best correlated with the need for stent-assisted coiling. Inclusion of MOA with the rest of the parameters significantly increased the predictive performance regarding the need for stent-assisted coiling (P = .005).

CONCLUSIONS

In this small study, MOA was a useful parameter to predict the need for stent-assisted coiling in ICA sidewall aneurysms. Further prospective study of this parameter for aneurysms at multiple locations is required to determine its ultimate value.

The Woven EndoBridge: a new aneurysm occlusion device

BACKGROUND AND PURPOSE

The WEB device is an intrasaccular ellipsoid braided-wire embolization device designed to provide flow disruption along the aneurysm neck. The purpose of this study was to evaluate, in an in vivo aneurysm model, the acute and chronic performance of the WEB device regarding immediacy, degree, and durability of aneurysm occlusion.

MATERIALS AND METHODS

The WEB device was implanted in 24 elastase-induced aneurysms in New Zealand white rabbits and followed for 1, 3, 6, and 12 months (n = 6 at all time points). Degree of intra-aneurysmal flow disruption was graded on a 4-point scale based on DSA within 10 minutes following device implantation. Chronic aneurysm occlusion was rated by using a 3-point scale. All aneurysms were harvested for histologic analysis.

RESULTS

Immediate postimplant grade 1 (complete flow cessation) was noted in 7 (29%) of 24 cases. Grade 2 (near-complete flow cessation) was noted in 13 (54%) of 24 cases. At follow-up, complete occlusion was noted in 8 (33%) of 24 cases. Near-complete aneurysm occlusion was noted in 14 (58%) of 24 cases, while incomplete occlusion was noted in 2 (8%) cases. Stable aneurysm occlusion was present in 7 (29%) of 24 cases; progressive occlusion, in 14 (58%); and recanalization, in 3 (13%) cases. Histologic findings included aneurysm cavities filled with organized thrombus with connective tissue across the aneurysm neck.

CONCLUSIONS

The WEB device in experimental aneurysms demonstrated promising rates of immediate and long-term aneurysm occlusion.

Stent-assisted coil embolization of a traumatic wide-necked renal segmental artery pseudoaneurysm

We present the case of an Afghan woman with a renal segmental artery false aneurysm of the right kidney due to a shell splinter injury. Stent-assisted coil embolization of the aneurysm is described in detail.

Early Migration of a Self Expanding Intracranial Stent

OBJECTIVE

With the development of support devices such as stents, an increasing number of aneurysms are meeting the criteria for endovascular treatment. A range of intracranial stents currently are available with an array of characteristics. It is essential to understand the properties of these stents to determine their role and implications in endovascular treatment of cerebral aneurysms.

CLINICAL PRESENTATION

A 45-year-old man presented to our institution with subarachnoid hemorrhage secondary to a small distal basilar trunk aneurysm.

INTERVENTION

An Enterprise stent (4.5 × 14 mm) was deployed in the parent vessel across the neck of the aneurysm. Repeat angiography 2 days later demonstrated significant proximal stent migration. A second, longer overlapping Enterprise stent (4.5 × 22 mm) was deployed from the left P1 segment into the basilar artery. Complete occlusion of the basilar trunk aneurysm was noted on subsequent angiography.

CONCLUSION

This is an unequivocal case of early spontaneous migration of a self-expanding intracranial stent. We suggest caution when there is significant discrepancy in luminal diameter and suboptimal wall apposition. Early imaging following stent deployment may be indicated in these cases.

Endovascular treatment of a fusiform cerebral aneurysm by stenting alone. Two case reports and literature review

This paper illustrates two cases of stent-in-stenting treatment of unruptured, symptomatic, fusiform intracerebral aneurysms. Two unruptured symptomatic fusiform intracerebral aneurysms were treated by the stent-in-stent only technique. The first patient, a 35-year-old woman, had a partially thrombosed fusiform aneurysm in the left carotid siphon with the chief complaint of headache and left ophthalmoplegia. The second patient, a 60-year-old man, had a symptomatic fusiform aneurysm of the left V4 with recurrent transient ischemic attacks. No cervical trauma or infection was present in either patient. A CT, CTA and DSA were performed on hospital admission. Both patients were previously premedicated with Clopidrogel + ASA for five days before treatment. By DSA, both patients were treated under general anesthesia with a heparin protocol plus ASA (500mg) at stent placement. A double stent-in stent was placed in both patients. Post-intervention medical therapy was clopridogel and ASA for three months, then aspirin (100mg) daily for six months. CTA and DSA were performed at six and 12 months. Both stents were positioned without any difficulty and could be navigated within cerebral arteries without any exchange procedure, and thanks to their retractability, they were accurately positioned. No bleeding at post-treatment CT was noted. At 12 months follow-up, a complete disappearance of the aneurysm and preservation of the parent vessel was observed for both patients. No procedure-related complication occurred. No intra-stent stenosis or intimal hyperplasia was observed. Stenting for fusiform aneurysms is a safe procedure without complications. Medical therapy pre-post procedure associated with follow-up is necessary to prevent/establish the incidence of occlusion.

Fast virtual deployment of self-expandable stents: method and in vitro evaluation for intracranial aneurysmal stenting

INTRODUCTION

Minimally invasive treatment approaches, like the implantation of percutaneous stents, are becoming more popular every day for the treatment of intracranial aneurysms. The outcome of such treatments is related to factors like vessel and aneurysm geometry, hemodynamic conditions and device design. For this reason, having a tool for assessing stenting alternatives beforehand is crucial.

METHODOLOGY

The Fast Virtual Stenting (FVS) method, which provides an estimation of the configuration of intracranial stents when released in realistic geometries, is proposed in this paper. This method is based on constrained simplex deformable models. The constraints are used to account for the stent design. An algorithm for its computational implementation is also proposed. The performance of the proposed methodology was contrasted with real stents released in a silicone phantom.

RESULTS

In vitro experiments were performed on the phantom where a contrast injection was performed. Subsequently, corresponding Computational Fluid Dynamics (CFD) analyzes were carried out on a digital replica of the phantom with the virtually released stent. Virtual angiographies are used to compare in vitro experiments and CFD analysis. Contrast time-density curves for in vitro and CFD data were generated and used to compare them.

CONCLUSIONS

Results of both experiments resemble very well, especially when comparing the contrast density curves. The use of FVS methodology in the clinical environment could provide additional information to clinicians before the treatment to choose the therapy that best fits the patient.

Early fatal hemorrhage after endovascular cerebral aneurysm treatment with a flow diverter (SILK-Stent): do we need to rethink our concepts?

A 69-year-old woman presenting with short lasting recent episodes of visual impairment was treated uneventfully with a flow diverter covering the neck of a large paraophthalmic aneurysm. As angiography showed immediate flow reduction we abstained from additional coiling which was initially planned. Eleven days later CT demonstrated nearly complete thrombosis of the aneurysm. Twenty days after treatment the patient suffered a lethal subarachnoid hemorrhage after rupture of the aneurysm. All available data were reviewed and beside hemodynamic factors instability of the intra-aneurysmal thrombus is discussed as a possible cofactor leading to this disastrous event.

3T MRI in the Evaluation of Brain Aneurysms Treated with Flow-Diverting Stents: Preliminary Experience

Deployment of stents across the neck of intracranial aneurysms to isolate the lesion from the circulation is a recently introduced endovascular treatment. These devices are known as flow-diverting stents because the stent mesh design drastically slows the blood flow within the aneurysm sac, thereby stimulating thrombus formation. Treated aneurysms require close follow-up monitoring using an effective minimally invasive method. We devised a dedicated follow-up protocol using a high field strength magnetic resonance system (MR) with gadolinium administration to monitor 11 patients treated by insertion of flow-diverting stents. Findings were compared with the results of a reference imaging procedure (CT angiography). MR accurately demonstrated patency of the stent lumen and monitored the evolution of the aneurysmal sac in all patients. Gadolinium administration proved essential in two patients to depict the complete exclusion of the flow within the aneurysmal sac.

Stent-assisted coil embolization of posterior circulation aneurysms using solitaire ab: preliminary experience

OBJECTIVE

To evaluate patients with wide-necked aneurysms of the posterior circulation who underwent Solitaire AB (ev3, Inc., Irvine, CA) stent-assisted coil embolization.

METHODS

Retrospective analysis of 10 patients (age range, 32-76 years; mean age, 59.1 years) with aneurysms of the basilar artery (basilar tip, n = 5; basilar trunk, n = 4; posterior cerebral artery, n = 1). Seven of the patients presented with an acute subarachnoid hemorrhage. Five aneurysms were small, 2 were large, and 3 were giant. All patients were treated by different applications (n = 14) of the Solitaire AB neurovascular remodeling device followed by a standard coiling procedure using bioactive coils.

RESULTS

Positioning of all Solitaire AB stents was easy and successful. No stent required retrieving and repositioning after full deployment. There were no thromboembolic complications, and no dissection/rupture or vasospasm occurred during stent placement. In all cases except 3, 100% lesion occlusion was observed after the initial treatment.

CONCLUSION

The initial technical and clinical results of Solitaire AB stent-assisted coiling of different types of wide-necked aneurysms in the posterior circulation are highly encouraging, and this technique may improve the endovascular treatment of these aneurysms.