Patency of the anterior choroidal artery after flow-diversion treatment of internal carotid artery aneurysms

Quantitative Analysis of Hemodynamic Changes in Branch Arteries Covered by Flow Diverters

BACKGROUND AND OBJECTIVES

Understanding post-treatment hemodynamic alterations and their association with the patency of covered branch arteries is limited. This study aims to identify hemodynamic changes after flow diverter stenting and investigate their correlation with the patency status of covered branch arteries.

METHODS

All patients treated with pipeline embolization device for anterior cerebral artery aneurysms at our center between 2016 and 2020 were screened for inclusion. Quantitative digital subtraction angiography was used to analyze changes in hemodynamic parameters pre- and post-stenting. The patency status of covered branch arteries after stenting was categorized as either patent or flow impairment (defined as artery stenosis or occlusion).

RESULTS

A total of 71 patients, encompassing 89 covered branch arteries, were enrolled. Flow impairment was observed in 11.2% (10/89) of the branches. The mean transit time and full width at half maximum (FWHM) in covered branches were significantly prolonged post-stenting (P = .004 and .023, respectively). Flow-impaired branch arteries exhibited hemodynamic shifts contrary to those in patent branch arteries. Specifically, flow-impaired branches showed marked reductions in time to peak, FWHM, and mean transit time (decreases of 32.8%, 32.6%, and 29%, respectively; P = .006, .002, and .002, respectively). Further multivariate analysis revealed that reductions in FWHM in the branches (odds ratio = 0.97, 95% CI: 0.95-0.99, P = .007) and smoking (odds ratio = 14.5, 95% CI: 1.39-151.76, P = .026) were independent predictors of flow impairment of covered branches.

CONCLUSION

Pipeline embolization device stenting can cause a reduction in blood flow in branch arteries. Compared with patent branches, flow-impaired branches exhibit an increase in blood flow velocity after stenting. Smoking and ΔFWHM in the covered branches indicate flow impairment.

Flow-diverter stents in intracranial aneurysm treatment: impact on covered cerebral artery branches

OBJECTIVE

Flow diverter stents (FDSs) have attracted interest for intracranial aneurysm (IA) treatment; however, occlusion of side branches and related complications have been reported. This study aimed to investigate the effects of FDSs in IA management when different branches of intracranial arteries are covered.

MATERIALS AND METHODS

A cross-sectional study was conducted using PUBMED, Embase, Web of Science, and Cochrane databases to include randomized or nonrandomized comparative-designed studies from January 2000 to August 2022 which reported outcomes of occlusion/narrowing of branches after IA treatment using FDSs. The PRISMA guidelines were used for our report. A random-effects meta-analysis was conducted to pool the outcomes, which included incidence rates of occlusion/narrowing of FDS-covered branches, branch occlusion-related symptoms, obliteration of IAs, and ideal clinical outcomes (modified Rankin Scale score ≤2).

RESULTS

The authors identified 57 studies involving 3789 patients with IA managed by FDSs covering different branches. During the median imaging follow-up at 12 months, the IA obliteration rate was satisfactory (>70%) when covering the ophthalmic artery (OA), posterior communicating artery (PComA), anterior choroidal artery (AChoA) or anterior cerebral artery (ACA), but not the middle cerebral artery-M2 segment (MCA-M2; 69.5%; 95% CI: 60.8-77.5%) and posterior inferior cerebellar artery (PICA; 59.1%, 13/22). The overall ideal clinical outcome was observed in 97.4% of patients (95% CI: 95.5-98.9%). Higher rates of occlusion/narrowing of branches were identified when FDSs covered the ACA (66.6%; 95% CI: 45.1-85.3%), PComA (44.3%; 95% CI: 34.2-54.6%), or MCA-M2 (39.2%; 95% CI: 24.5-54.7%); the risks were lower when covering the OA (11.8%; 95% CI: 8.8-15.1%), PICA (6.8%; 95% CI: 1.5-14.5%), and AchoA (0.5%; 95% CI: 0.0-2.9%). The risk of branch occlusion-related complications was low (incidence rate <5%) for each of the six evaluated branches.

CONCLUSIONS

Acceptable outcomes were identified following treatment of IAs when FDSs were placed across each of the six studied cerebral arteries. Treatment decisions regarding FDS placement across branch arteries should be made with the risk of complications from branch occlusion in mind.

Use of a flow diverter in a small-caliber end artery anterior choroidal dissecting pseudoaneurysm: illustrative case

BACKGROUND

Anterior choroidal artery (AChA) fusiform aneurysms are exceedingly rare and associated with high rebleeding and mortality rates. Their difficult anatomy comes with a broad range of treatment options, including bypass, stent-assisted coiling, and flow diversion. Currently, flow diverters are approved for large-caliber internal carotid artery segment aneurysms. However, many institutions have expanded their use to distal small-caliber vessels, which raises questions regarding device sizing and long-term patency. The authors present a dissecting distal AChA fusiform pseudoaneurysm treated successfully with flow diversion.

OBSERVATIONS

A 40-year-old woman with monoclonal gammopathy of unknown significance, lichen sclerosis, and an unspecified connective tissue disease presented with diffuse subarachnoid hemorrhage. She had a dissecting, 5 × 3-mm, left AChA pseudoaneurysm 4 mm distal to the origin of the vessel. A 2.5-mm flow redirection endoluminal device was deployed. There were no procedural complications. A 6-month cerebral angiogram showed device patency and no pseudoaneurysm remnant. These results were maintained at 1 year as seen on head magnetic resonance angiography.

LESSONS

Flow diversion is a successful and safe therapeutic intervention for challenging intracranial aneurysms originating from small-caliber vessels supplying eloquent vascular territories.

Plasticity of the adult circle of Willis in response to flow diversion stents

Background

We present five patients with remodeling of the adult circle of Willis in response to flow diverter stents (FDSs) at the anterior communicating artery (AComA) and the posterior communicating artery (PComA). The observed changes provide a paradigm of how flow change can institute anatomic changes in the adult circle of Willis vasculature.

Case Description

In the first two cases, after placement of the FDS covering the AComA, there was an increase in size and flow of the contralateral A1-anterior cerebral artery which had previously been hypoplastic. In one of the cases, this led to the filling of the aneurysm and required placement of coils within the lesion which was curative. In case three, the FDS effect led to asymptomatic occlusion of the PComA and associated aneurysm without change of the ipsilateral P1-segement of posterior-cerebral-artery (P1-PCA) caliber. In the fourth case, the FDS covering an aneurysm with a fetal PCA arising from its neck resulted in significant reduction of the aneurysm size, persistent flow and caliber of the fetal PCA, and the hypoplastic ipsilateral P1-PCA. Finally, in the fifth case, after FDS occlusion of the PComA and aneurysm there was increasement in diameter of the ipsilateral P1-PCA that was previously hypoplastic.

Conclusion

The use of FDS can affect vessels covered by the device and other arteries of the circle of Willis adjacent to the FDS. The phenomena illustrated in the hypoplastic branches appear to be a compensatory response to the hemodynamic changes induced by the divertor and to the altered flow in the circle of Willis.

Diagnostic Impact of Monitoring Visual Evoked Potentials to Prevent Visual Complications During Endovascular Treatment for Intracranial Aneurysm

Introduction

The present study aimed to determine the incidence of intraprocedural visual-evoked potential (VEP) changes and to identify correlations with intraprocedural ischemic complications during endovascular treatment in patients with intracranial aneurysm related to visual function.

Methods

This study analyzed data from 104 consecutive patients who underwent endovascular coil embolization to treat intracranial aneurysms related to visual function under VEP and transcranial motor evoked potential (MEP) monitoring. We analyzed associations between significant changes in MEP and VEP, defined as a >50% decrease in amplitude, and both intraprocedural complications and postoperative neurological deficits. Factors associated with postoperative neurological deficits were also assessed.

Results

Treated aneurysms were predominantly located in the internal carotid artery (95%). Five (5%) were located in the posterior cerebral artery (PCA). Significant decreases in intraprocedural VEP occurred in four patients (4%), although one of those four patients did not show concomitant MEP decreases during procedures. Immediate salvage procedures avoided postoperative visual disturbances. All VEP decreases were transient and not associated with postoperative visual impairment. One of three cases who underwent intraoperative balloon occlusion test showed tolerance to balloon occlusion of the proximal PCA under VEP assessment; parent artery occlusion was performed without postoperative visual disturbance in that case.

Conclusion

Although significant VEP decreases occurred 4% during neuro-endovascular aneurysm treatment related to visual function, intraprocedural VEP monitoring identifies ischemic changes associated with visual pathways and facilitates prompt initiation of salvage procedures.

Endoluminal flow diverters in the treatment of sidewall and bifurcation aneurysm: A systematic review and meta-analysis of complications and angiographic outcomes

BACKGROUND AND AIM

The use of endoluminal flow diversion in bifurcation aneurysms has been questioned due to the potential for complications and lower occlusion rates. In this study we assessed outcomes of endovascular treatment of intracranial sidewall and bifurcation aneurysms with flow diverters.

METHODS

In July 2020, a literature search for all studies utilizing endoluminal flow diverter treatment for sidewall or bifurcation aneurysms was performed. Data were collected from studies that met our inclusion/exclusion criteria by two independent reviewers and confirmed by a third reviewer. Using random-effects meta-analysis the target outcomes including overall complications (hematoma, ischemic events, minor ischemic stroke, aneurysm rupture, side vessel occlusion, stenosis, thrombosis, transient ischemic stroke, and other complications), perioperative complications, and follow-up (long-term) aneurysm occlusion were intestigated.

RESULTS

Overall, we included 35 studies with 1084 patients with 1208 aneurysms. Of these aneurysms, 654 (54.14%) and 554 (45.86%) were classified as sidewall and bifurcation aneurysm, respectively, based on aneurysm location. Sidewall aneurysms had a similar total complication rate (R) of 27.12% (95% CI, 16.56%-41.09%), compared with bifurcation aneurysms (R, 20.40%, 95% CI, 13.24%-30.08%) (p = 0.3527). Follow-up angiographic outcome showed comparable complete occlusion rates for sidewall aneurysms (R 69.49%; 95%CI, 62.41%-75.75%) and bifurcation aneurysms (R 73.99%; 95% CI, 65.05%-81.31%; p = 0.4328).

CONCLUSIONS

This meta-analysis of sidewall and bifurcation aneurysms treated with endoluminal flow diverters demonstrated no significant differences in complications or occlusion rates. These data provide new information that can be used as a benchmark for comparison with emerging devices for the treatment of bifurcation aneurysms.

Institutional experience of in-stent stenosis after pipeline flow diverter implantation: A retrospective analysis of 6 isolated cases out of 118 patients

Pipeline embolization devices (PLEDs) are flow diverting stents that have exhibited be safe and efficient in the treatment of complex aneurysms. Nevertheless, in-stent stenosis (ISS) has been reported as one of the cardinal complications associated with PLED. The association of wall malapposition and ISS in patient treated with PLED has not been reported.A retrospective study was conducted to identify patients with ISS after implantation of PLED as treatment for intracranial aneurysms from April 25, 2018 to April 24, 2019. Incidence of ISS and its associated causes such as sharp change of the PLED, distal wall malapposition, inconsistent compliance between parent artery as well as the PLED occlusion due to intimal hyperplasia and vessel tortuosity. Assessment of conservative treatment and retreatment outcomes of ISS were documented.In all, 6 ISS cases were identified by 2 independent neurointerventionalists out of 118 aneurysm patients treated with PLED. Thus, the incidence rate of ISS in patients treated with PLED was as low as 5% at our institution compared to other studies. The follow-up time for detection of ISS ranged from 6 to 12 months after implantation. Several combinations of reasons such as sharp change of the PLED, distal wall malapposition, inconsistent compliance between parent arteries as well as PLED occlusion due to intimal hyperplasia and vessel tortuosity accounted for the causes of ISS during our analysis. Conservative treatment with a combination of antiplatelet during follow-ups did not resolve the ISS in our study probably due to associated underlying factors above.

Delayed Occlusion of the Anterior Choroidal Artery Following Flow Diverter Stent Deployment for Unruptured Aneurysm: A Case Report and Literature Review

Flow diverter stent has been a promising device for intracranial aneurysm treatment. For treating aneurysms located in the anterior circulation, critical branches may be covered by flow diverter stent. The occlusion incidence of these branches has been reported, and even if branch vessel occlusions occur, associated neurological deficits are extremely rare. We present a 55-year-old woman who had a large saccular aneurysm at the right internal carotid artery (ICA). A developed fetal-type posterior communicating artery (PCOM) originated from the sac. We administered flow diverter stent deployment with coil insertion following surgical anastomosis of the superficial temporal artery to the posterior cerebral artery (STA-PCA) with ligation of the origin of the PCOM. On the seventh morning following the intervention, ischemic complication developed due to anterior choroidal artery occlusion jailed by the flow diverter stent. The occlusion of anterior choroidal artery covered by flow diverter stent is extremely rare. However, if the branch arises from the aneurysm sac, occlusion can transpire and induce serious complication. The most probable cause of occlusion in this case was that the orifice was jailed apart from the stent strut because the branch originated from the sac rather than the neck. Furthermore, the progression rate of intra-aneurysm thrombus formation is also an important factor affecting the side branch occlusion.

Failure of Flow Diverter Therapy: Predictors and Management Strategies

Flow diversion is a safe and effective treatment for many types of brain aneurysms. Even so, there remain some aneurysms that persist despite initial treatment. In studies with the longest follow-up (5 yr), at least 5% of aneurysms persist with this treatment modality. As the cumulative experience and clinical indications for flow diversion continue to expand, the anatomic and functional characteristics that are associated with aneurysm persistence are increasingly described. Identification of these factors preoperatively can help to guide initial treatment decisions, enhance monitoring protocols in the follow-up period, and establish best practices for re-treatment when necessary. Herein, we review published clinical series and provide examples to highlight variables implicated in aneurysm persistence after treatment with flow diversion.

Expanding the Indications for Flow Diversion: Treatment of Posterior Circulation Aneurysms

Posterior circulation aneurysms are often associated with a higher risk of rupture and compressive symptoms compared to their anterior circulation counterpart. Due to high morbidity and mortality associated with microsurgical treatment of those aneurysms, endovascular therapy gained ascendance as the preferred method of treatment. Flow diversion has emerged as a promising treatment option for posterior circulation aneurysms with a higher occlusion rate compared to other endovascular techniques and a lower complication rate compared to microsurgery. While treatment of saccular and dissecting aneurysms is often associated with comparatively good outcomes, fusiform and dolichoectatic aneurysms should be carefully selected prior to treatment to avoid devastating thromboembolic complications. Occlusion of covered posterior circulation branches showed no correlation with ischemic complications, and appropriate antiplatelet regimen and switching Clopidogrel nonresponders to different antiplatelet agents were associated with lower complication rates following flow diversion of posterior circulation aneurysms.

Branch vessel occlusion in aneurysm treatment with flow diverter stent

Flow diverter placement for treatment of intracranial aneurysms gained growing consensus in the past years. A major concern among professionals is the side branch coverage which leads in some cases to vessel occlusion. However, the lost vessel patency only infrequently is accompanied by a new onset of neurological deficits secondary to ischaemic lesions. A retrospective analysis of all patients treated with flow diversion at our hospital was aimed to better understand this phenomenon in order to formulate a hypothesis about the causes. We concluded that vessel occlusion occurs due to a reduced blood pressure gradient in those vessels with a strong collateral or anastomotic vascularization that refurnishes the same distal vascular territories. Indeed, we detected no new brain infarction since blood flow was always guaranteed.

Flow Diversion for Intracranial Aneurysm Treatment: Trials Involving Flow Diverters and Long-Term Outcomes

Flow diverters (FDs) have changed the management of brain aneurysms; not only for complex aneurysms (giant, fusiform and blister) refractory to conventional therapies, but also for unruptured lesions previously managed by traditional surgical or coil-based endovascular methods. Since 2011 when the PipelineTM Embolization Device (Medtronic) was cleared by the Food and Drug Administration for adults with large or giant wide-neck intracranial aneurysms of the internal carotid artery proximal to the posterior communicating segment, the role of flow diversion for aneurysm treatment has expanded—supported by favorably low complication and high cure rates compared with alternative treatments. Here we review the key clinical trials and the long term outcomes that have demonstrated safety and efficacy of minimized porosity endoluminal devices in the treatment of cerebral aneurysms.

The p64 Flow Diverter-Mid-term and Long-term Results from a Single Center

BACKGROUND AND PURPOSE

The p64 is a flow modulation device designed to be used in endovascular treatment of intracranial aneurysms. There is limited data on the long-term effectiveness of the device. This study sought to determine the safety and long-term efficacy of this device.

METHODS

A retrospective review of a prospectively maintained database was performed to identify all patients treated with a p64 between March 2015 and November 2018 at University Hospital St. Ivan Rilski. Anatomical features, intraprocedural complications, clinical, and angiographic outcomes were also taken into account and reviewed.

RESULTS

A total of 72 patients with 72 aneurysms who met the inclusion criteria were identified. Device placement was successful in all patients. Follow-up angiographic imaging at 6 months showed complete occlusion (O'Kelly-Marotta scale [OKM] D) in 55 (76.3%) patients, subtotal aneurysmal filling (OKM B) in 10 (13.8%) patients, and neck remnant (OKM C) in 7 (9.7%) patients. Catheter angiography at 12 months was available for 70 patients (97.2%) and of these patients 91.4% of the aneurysms were completely occluded (OKM D) (64/72). Delayed angiography at 24 months was available for 68 patients (94.4%) and of these 98.5% (67/68) had completely occluded aneurysms. A 36-month angiography was available for 61 patients (84.4%) by which point all aneurysms had been completely occluded (100%). Permanent morbidity due to delayed aneurysmal rupture occurred in one patient (1.38%). The mortality rate was 0%. Self-limiting mild intimal hyperplasia was seen in 2 patients (2.72%).

CONCLUSION

Treatment of intracranial aneurysms with a p64 flow modulation device is safe and effective with a high success rate and only infrequent complications.

Patency of Branch Vessels After Pipeline Embolization: Comparison of Various Branches

Objective: Pipeline embolization devices (PEDs) are widely used to exclude intracranial aneurysms from their parent arteries. Side branches covered by PEDs, however, sometimes experience occlusion and related symptoms. Thus, predictors of branch occlusion and the patency and clinical outcomes of these branches are concerning.

Methods: We conducted a retrospective review of consecutive patients who had been treated with PEDs in our institution during 2015–2018 to identify those in whom one or more branches were involved. Pretreatment and follow-up angiograms were assessed to determine patency of the involved branches. Demographic and clinical data, treatment strategies, and comorbidities were collected to investigate their relations with branch occlusion.

Results: Altogether, 173 branches [24 (13.9%) occluded), 29 (16.8%) with diminished flow] in 126 patients were studied. Five patients (OphA involved) presented with blurred vision and 1 patient (ACA involved) presented with headache. None of the other patients had neurologic complications or clinical strokes related to branch occlusion. Multivariate analysis identified that small PED diameter [p = 0.003, odds ratio (OR) = 0.168], branches arising from the aneurysm (p = 0.004, OR = 6.614), and involvement of the anterior cerebral artery (ACA) (p < 0.001, OR = 25.656) significantly predicted branch occlusion.

Conclusion: Branch occlusion rate after PED deployment was low and most occlusions was asymptomatic. Branches with rich collateral supply were more likely to occlude, especially the ACA. Smaller PED diameter, branches arising from the aneurysm, and ACA involvement were significant predictors of branch occlusion after PED treatment.

Hemodynamic Fate of the Precommunicating Anterior Cerebral Artery Is Predicted by Vessel Dominance After Pipeline Embolization Device Deployment Across the Internal Carotid Artery Terminus

BACKGROUND

The Pipeline embolization device (PED) is commonly used for the treatment of distal internal carotid artery (ICA) aneurysms, which often require placing the stent across the origin of the precommunicating segment of the anterior cerebral artery (ACA-A1). We sought to characterize the clinical and angiographic consequences of this maneuver.

METHODS

We performed a retrospective review of a prospectively collected database of patients treated with the PED at a single academic center from 2011 to 2017 to find patients for whom the PED was extended across the origin of the ACA-A1. The patient demographic data, pretreatment angiographic imaging findings, sizing of the bilateral A1 and ipsilateral M1 segment of the middle cerebral artery (MCA-M1), and follow-up angiographic and clinical imaging findings were recorded.

RESULTS

A total of 27 patients were included in the present study (8 men and 19 women; age, 52 ± 14.9 years). Follow-up angiography was conducted at a median of 9.2 months (interquartile range, 6; range, 5-84). The covered A1 segment was patent in 17 patients (63%). The covered ACA-A1/ipsilateral MCA-M1 ratio was 1.43 times greater for the patent ACA-A1 segments than those that were occluded (P = 0.0006). Similarly, the covered ACA-A1/contralateral ACA-A1 ratio was significantly larger statistically (1.64; P < 0.0001) for the patent ACA-A1 segments than that for those that were occluded. None of the patients developed clinical or radiographic signs of ACA stroke. The modified Rankin scale worsened for 1 patient during follow-up owing to a further decline of presenting vision loss.

CONCLUSIONS

The PED can be used to treat aneurysms with deployment from the MCA-M1 to the ICA without resulting in ACA stroke. Ipsilateral A1 segment dominance might be predictive of continued blood flow into the ACA after deployment at this location.

The Role of Collateral Circulation in Branch Vessel Occlusion After Flow Diversion

BACKGROUND

Flow diversion for treatment of intracranial aneurysms frequently necessitates covering adjacent branch vessels. Although branch vessel occlusion is common, associated clinical deficits are rare. It has been hypothesized that clinically silent branch vessel occlusion is due to underlying collateral circulation. To study the role of collateral circulation in covered branch vessel occlusion, we assessed collateral vessels and altered branch vessel flow on transfemoral catheter angiography in patients undergoing flow diversion of intracranial aneurysms.

METHODS

Angiograms obtained before treatment, immediately after treatment, and during follow-up were evaluated for branch vessel flow patterns and associated collateral circulation in a consecutive retrospective cohort of 84 patients from 2011 to 2017 with branch vessel coverage related to aneurysm flow diversion using the Pipeline embolization device.

RESULTS

We identified 142 branch vessels covered by the Pipeline device construct for treatment of 89 aneurysms, predominately in the anterior circulation (>90%). Collateral circulation was observed in approximately one third of these vessels and was associated with diminished (P < 0.001) or absent (P < 0.001) flow on follow-up angiography. Only 2 of 80 terminal branch vessels (no collaterals) were occluded, and these occurred in a patient with Pipeline device construct thrombosis. Altered branch vessel flow was not associated with vascular risk factors, treatment technique, or outcome measures, including new or worsening neurologic deficit.

CONCLUSIONS

Altered flow in branch vessels covered during flow diversion reflects underlying collateral circulation and is not associated with downstream ischemic deficits.

Flow diversion covering the M1 origin as a last resort

Introduction

Internal carotid artery termination (ICAT) and proximal A1 aneurysms can be challenging for open surgical clipping or endovascular coiling. Treatment with flow diversion covering the middle cerebral artery (MCA), an end vessel supplying a terminal circulation, has not been reported.

Methods

A prospective, Institutional Review Board-approved database was analysed for patients with pipeline embolisation device (PED) placement from the anterior cerebral artery (ACA) to the ICA during cerebral aneurysm treatment.

Results

Nine cases were identified, including five proximal A1, three posterior communicating artery and one ICAT aneurysm locations. Average aneurysm size was 8.3 mm (range 3-17), with 67% saccular and 78% right-sided. Primary indication for treatment was significant dome irregularity (44%), recurrence or enlargement (33%), underlying collagen vascular disorder (11%) and traumatic pseudoaneurysm (11%). Preservation of the ipsilateral ACA (with PED placed in A1) was performed when the anterior communicating artery (67%) or contralateral A1 (33%) were absent on angiography. Adjunctive coiling was done in four cases (44%). There was one major stroke leading to mortality (11%) and one minor stroke (11%). Clinical follow-up was 27 months on average. Follow-up digital subtraction angiography (average interval 15 months) showed complete aneurysm obliteration (88%) or dome occlusion with entry remnant (12%). The jailed MCA showed minimal or mild delay (primarily anterograde flow) in 75% of cases and significant delay (reliance primarily on ACA and external carotid artery collaterals) in 25%.

Conclusions

Covering the MCA with a flow diverting stent should be reserved for select rare cases. Strict attention to blood pressure augmentation during the periprocedural period is necessary to minimise potential ischaemic compromise.

Patency of anterior choroidal artery after flow diverter deployment with assessment of magnetic resonance imaging follow-up

PURPOSE

We aimed to analyse the patency rate of the anterior choroidal artery, and presented imaging and neurological findings, after deployment of a flow diverter in the anterior choroidal artery in the treatment of patients with intracranial aneurysms.

METHODS

Among the 139 patients who underwent a flow diverter deployment from December 2012 to September 2017 in our hospital, there were 21 patients (15.1%) for whom their anterior choroidal artery was covered for the procedure with a flow diverter. The patients' age, sex, size of aneurysm and the presence or absence of an anterior choroidal artery occlusion, neurological findings and postoperative infarction in the anterior choroidal artery region were analysed retrospectively.

RESULTS

The mean age of the six male and 15 female patients was 61.5 years (range 32-77 years). The mean maximal diameter of the aneurysms was 16.4 mm (range 10.0-29.4 mm). The anterior choroidal artery was patent in all 21 patients; however, a haemodynamic alteration in the anterior choroidal artery was detected in one patient. Postoperatively, hemiparesis was observed in two patients (9.5%) and a visual field defect in one patient (4.8%), both of which were the symptoms of infarction of the cortical branch of the middle cerebral artery or retinal artery ischaemia. However, no patients had symptoms due to ischaemia of the anterior choroidal artery confirmed with magnetic resonance imaging.

CONCLUSIONS

In all patients who underwent flow diverter deployment, the anterior choroidal artery was patent and no ischaemia was detected in the imaging or evidenced by neurological findings. Therefore, flow diverter deployment in the anterior choroidal artery was considered to be a safe procedure.

Flow-Diversion Effect of LEO Stents: Aneurysm Occlusion and Flow Remodeling of Covered Side Branches and Perforators

BACKGROUND AND PURPOSE

Flow diversion with intermediate-porosity stents (braided stents) has been recently reported for distally located small aneurysms. The aim of this study was to evaluate the flow-diversion effect of LEO stents on covered vessels and for aneurysms treated with sole stent-placement therapy.

MATERIALS AND METHODS

We retrospectively evaluated the following outcomes: 1) remodeling of covered side branches and perforators (extra-aneurysmal flow remodeling), and 2) the occlusion rate of aneurysms treated with sole stent-placement therapy (intra-aneurysmal flow remodeling).

RESULTS

Seventy-six patients with 98 covered vessels were studied. Overall, 89 covered arteries (91%) were normal, 7 showed narrowing (7%), and 2 (2%) were occluded (1 posterior communicating artery and 1 MCA) without related complications (mean DSA follow-up, 14 months). Univariate and multivariate analyses highlighted smoking (P = .03) and the length of follow-up (P = .002) as factors associated with arterial remodeling. Of the 17 Sylvian (lenticulostriate arteries) and 7 basilar perforators, 1 (4%) group of Sylvian perforators covered with double stents had asymptomatic remodeling. Ten aneurysms (mean size, 3.5 mm) were treated with LEO stents as stent monotherapy (5 recanalized after coiling and 5 directly treated with the LEO). Complete occlusion (Raymond-Roy I) was achieved in 70% of aneurysms (mean follow-up, 14 months). The Raymond-Roy I occlusion rate among recanalized aneurysms and those directly treated with LEO stents was 80% and 60%, respectively (P = .9).

CONCLUSIONS

The rate of flow remodeling on the covered arteries and perforators was 9% and 4%, respectively, and was clinically irrelevant in all cases. Complete occlusion of aneurysms treated with sole stent-placement therapy was 70%. These data stress the flow-diversion properties of LEO stents.

Use of Flow Diversion for the Treatment of Distal Circulation Aneurysms: A Multicohort Study

OBJECTIVE

The safety and efficacy of flow diversion for distal circulation aneurysms of the cerebral vasculature has not been well evaluated. The objective of this study was to assess the use of flow diversion for distal circulation aneurysms (defined as at or beyond the M1, P1, and A1 segments of the middle cerebral artery, posterior cerebral artery, and anterior cerebral artery, respectively) in an international multicenter cohort.

METHODS

Clinical and radiologic records from all patients undergoing flow diversion treatment of distal circulation aneurysms at 3 academic centers (2 in the USA and 1 in Europe) from 2014 until 2017 were retrospectively reviewed.

RESULTS

Forty-six patients (mean age, 58.2 years; 33 women) harboring 46 aneurysms who underwent treatment with either the Pipeline Embolization Device (Medtronic Inc., Dublin, Ireland) or the Flow Re-Direction Endoluminal Device (MicroVention, Tustin, California, USA) were included in these analyses. Thirty-four aneurysms (74%) were located in the anterior circulation and 12 (26%) were located in the posterior circulation. With a mean follow-up of 13.0 months, complete (100%) and near-complete (90%-99%) occlusion was noted in 36 aneurysms (78.2%). Angiographic evidence of side branch or perforator vessel coverage was present in 35 aneurysms (76.1%) but was not associated with failure to occlude at follow-up (P = 0.06). All patients had good functional outcomes after treatment (modified Rankin Scale score 0-2). There were 2 cases (4.3%) of perforator vessel stroke and no hemorrhagic complications.

CONCLUSIONS

Flow diversion for aneurysms beyond the circle of Willis has occlusion rates comparable to alternative treatments and low morbidity. The clinical significance of flow limitation through covered side branches requires further investigation.

Risk of Branch Occlusion and Ischemic Complications with the Pipeline Embolization Device in the Treatment of Posterior Circulation Aneurysms

BACKGROUND AND PURPOSE

Flow diversion with the Pipeline Embolization Device is increasingly used for endovascular treatment of intracranial aneurysms due to high reported obliteration rates and low associated morbidity. While obliteration of covered branches in the anterior circulation is generally asymptomatic, this has not been studied within the posterior circulation. The aim of this study was to evaluate the association between branch coverage and occlusion, as well as associated ischemic events in a cohort of patients with posterior circulation aneurysms treated with the Pipeline Embolization Device.

MATERIALS AND METHODS

A retrospective review of prospectively maintained databases at 8 academic institutions from 2009 to 2016 was performed to identify patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. Branch coverage following placement was evaluated, including the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and posterior cerebral artery. If the Pipeline Embolization Device crossed the ostia of the contralateral vertebral artery, its long-term patency was assessed as well.

RESULTS

A cohort of 129 consecutive patients underwent treatment of 131 posterior circulation aneurysms with the Pipeline Embolization Device. Adjunctive coiling was used in 40 (31.0%) procedures. One or more branches were covered in 103 (79.8%) procedures. At a median follow-up of 11 months, 11% were occluded, most frequently the vertebral artery (34.8%). Branch obliteration was most common among asymptomatic aneurysms (P < .001). Ischemic complications occurred in 29 (22.5%) procedures. On multivariable analysis, there was no significant difference in ischemic complications in cases in which a branch was covered (P = .24) or occluded (P = .16).

CONCLUSIONS

There was a low occlusion incidence in end arteries following branch coverage at last follow-up. The incidence was higher in the posterior cerebral artery and vertebral artery where collateral supply is high. Branch occlusion was not associated with a significant increase in ischemic complications.

The use of flow diverters to treat aneurysms of the posterior inferior cerebellar artery: Report of three cases

Objective The objective of this study was to report our experience on the use of flow diverting stents placed within the posterior inferior cerebellar artery (PICA) as a treatment option for aneurysms of the PICA. Methods Three patients with aneurysms of the PICA, both ruptured and unruptured, underwent treatment of their aneurysms with placement of a single flow diverter in the PICA across the neck of the aneurysm. Adjunctive techniques such as coiling were not used. We present the angiographic and clinical follow-up data. Results The procedure was a technical success in all cases and there were no intraoperative complications. Follow-up data were available for two patients and this showed complete occlusion of the aneurysm with the PICA remaining patent. There was no evidence, either clinical or radiological, of medullary or pontine infarction. One patient died during the follow-up period from an unrelated medical illness (community acquired pneumonia). Conclusion Flow diverters can be successfully placed within the PICA to treat both ruptured and unruptured aneurysms, and they represent an alternative treatment option to endovascular coiling or microscopic neurosurgery.

Silk flow-diverter stent for the treatment of complex intracranial aneurysms: A one-year follow-up multicenter study

Background Flow-diverter stents have been successfully used in the treatment of complex aneurysms with limited therapeutic alternatives. We report our experience using the Silk flow diverter (SFD; Balt Extrusion, Montmorency, France) for the treatment of complex aneurysms in four Argentine centers. Methods We conducted a retrospective review of 246 consecutive patients who were treated with the SFD at four Argentine centers between January 2009 and January 2017. The patient and aneurysm characteristics, as well as the details of the procedure, were analyzed. The angiographic and clinical findings were recorded during and immediately after the procedure and at 12-month follow-up. Results Angiography follow-up at 12 months was possible in 235 patients (95.5%) with 282 aneurysms. A total of 265 aneurysms (93.9%) presented with complete occlusion of the aneurysmal sac (class 1) and 17 aneurysms (6.1%) presented with partial occlusion (class 2). The 12-month clinical follow-up showed 11 patients with major events (seven, scale 2; five, scale 3; and two, scale 4). The morbidity and mortality rates were 4.2% (11/289) and 2.1% (5/289), respectively. Conclusions The treatment of aneurysms with the SFD was associated with a low rate of complications and a high percentage of aneurysmal occlusion. These findings suggest that SFD is an effective and safe alternative in the endovascular treatment of complex aneurysms.

Long-term visual outcome in patients treated by flow diversion for carotid-ophthalmic aneurysms

BACKGROUND

Flow-diverter stents (FDSs) are an upgrade in the treatment of intracranial aneurysms. However, complications concerning covered branches have been reported, especially the ophthalmic artery (OA). The purpose of our study was to evaluate the long-term ophthalmic complication rate of carotid-ophthalmic aneurysms (COA) without visual pathways compression, treated by a FDS covering the OA by performing an exhaustive ophthalmic examination.

MATERIAL AND METHODS

Retrospective analysis of a single-center database screening the patients treated from October 2009 to April 2015 for an intracranial aneurysm with a FDS. The patients treated for a non-compressive COA with coverage of the OA by the device were studied (n=30). Among these patients, 15 (50%) were excluded. The remaining 15 patients underwent a systematic and extensive ophthalmic examination at least 2 years after the stent placement by two ophthalmologists.

RESULTS

Fifteen patients with 16 COAs treated with a FDS were included. Mean follow-up was 4.1±2 years. Six patients (40%), presented ophthalmic complications, including three fugax amauroses (18.8%) and four significant visual field defects (25%). After comparing each eye's visual field's patients, we observed a significant difference between the eye on the FDS side compared with the contralateral eye, with a mean deviation of -1.58 dB versus -0.67 dB respectively (P=0.003). Visual acuity was preserved in all patients.

CONCLUSION

Patients treated by FDS for COA have a good long-term clinical ophthalmic outcome. However, extensive ophthalmic examination shows a high percentage of minor ophthalmic modifications. Interventional neuroradiologists should be aware of these possible complications when choosing to treat these aneurysms with FDS.

Treatment of Unruptured, Saccular, Anterior Choroidal Artery Aneurysms with Flow Diversion : A Single Centre Experience

Background

The region of the brain supplied by the anterior choroidal artery (AChoA) is exquisitely eloquent. Aneurysms arising at or close to the origin of the vessel are not uncommon and damage or occlusion to the vessel can result in devastating consequences. The optimal treatment strategy is yet to be determined.

Objective

We sought to determine the efficacy of flow diversion for the treatment of unruptured AChoA aneurysms.

Method

A retrospective review of our prospectively maintained database was performed to identify all patients with unruptured aneurysms of the AChoA between March 2009 and May 2017. The fundus size, number and type of flow-diverting stent (FD), complications and follow-up data were recorded.

Results

We identified 30 patients (60% female), average age 52.8 ± 10.8 years (range 27–73), with 30 aneurysms. The aneurysms were generally small with a mean fundus diameter of 3.4 mm (range 1–7 mm). Early angiographic follow-up data were available for all patients at which point 15 aneurysms were completely occluded (50%). Delayed angiographic follow-up was available in 24 patients and occlusion was seen in 21 patients (87.5%). Of the patients one developed transient ischemic symptoms after interruption of the antiplatelet medication and another patient had a small embolic infarct with transient symptoms in the periprocedural period.

Conclusion

Flow diversion can be used to successfully treat aneurysms of the AChoA. The treatment carries a high rate of technical and radiological success with a good safety profile.

Clinical importance of the anterior choroidal artery: a review of the literature

The anterior choroidal artery (AChA) is a critical artery in brain physiology and function. The AChA is involved in many diseases, including aneurysm, brain infarct, Moyamoya disease (MMD), brain tumor, arteriovenous malformation (AVM), etc. The AChA is vulnerable to damage during the treatment of these diseases and is thus a very important vessel. However, a comprehensive systematic review of the importance of the AChA is currently lacking. In this study, we used the PUBMED database to perform a literature review of the AChA to increase our understanding of its role in neurophysiology. Although the AChA is a small thin artery, it supplies an extremely important region of the brain. The AChA consists of cisternal and plexal segments, and the point of entry into the choroidal plexus is known as the plexal point. During treatment for aneurysms, tumors, AVM or AVF, the AChA cisternal segments should be preserved as a pathway to prevent the infarction of the AChA target region in the brain. In MMD, a dilated AChA provides collateral flow for posterior circulation. In brain infarcts, rapid treatment is necessary to prevent brain damage. In Parkinson disease (PD), the role of the AChA is unclear. In trauma, the AChA can tear and result in intracranial hematoma. In addition, both chronic and non-chronic branch vessel occlusions in the AChA are clinically silent and should not deter aneurysm treatment with flow diversion. Based on the data available, the AChA is a highly essential vessel.

Complications associated with the use of flow-diverting devices for cerebral aneurysms: a systematic review and meta-analysis

OBJECTIVE

The objective of this study was to review the literature on the use of flow-diverting devices (FDDs) to treat intracranial aneurysms (IAs) and to investigate the safety and complications related to FDD treatment for IAs by performing a meta-analysis of published studies.

METHODS

A systematic electronic database search was conducted using the Springer, EBSCO, PubMed, Medline, and Cochrane databases on all accessible articles published up to January 2016, with no restriction on the publication year. Abstracts, full-text manuscripts, and the reference lists of retrieved articles were analyzed. Random-effects meta-analysis was used to pool the complication rates across studies.

RESULTS

Sixty studies were included, which involved retrospectively collected data on 3125 patients. The use of FDDs was associated with an overall complication rate of 17.0% (95% confidence interval [CI] 13.6%–20.5%) and a low mortality rate of 2.8% (95% CI 1.2%–4.4%). The neurological morbidity rate was 4.5% (95% CI 3.2%–5.8%). No significant difference in the complication or mortality rate was observed between 2 commonly used devices (the Pipeline embolization device and the Silk flow-diverter device). A significantly higher overall complication rate was found in the case of ruptured IAs than in unruptured IA (odds ratio 2.3, 95% CI 1.2–4.3).

CONCLUSIONS

The use of FDDs in the treatment of IAs yielded satisfactory results with regard to complications and the mortality rate. The risk of complications should be considered when deciding on treatment with FDDs. Further studies on the mechanism underlying the occurrence of adverse events are required.

The Fate of Side Branches Covered by Flow Diverters-Results from 140 Patients

BACKGROUND

Flow diverter stents (FDS) are a recognized treatment option for intracranial aneurysms. There remain ongoing concerns regarding the safety of FDS, especially regarding the fate of covered side branches. We report the patency of side branches covered by FDS.

METHODS

We retrospectively reviewed our database of prospectively collected information for all patients treated with FDS for an unruptured saccular aneurysm of the clinoid, ophthalmic, and terminating segments of the internal carotid artery between September 2009 and July 2016. The aneurysm location, fundus size, and the state of covered branches at last angiography were recorded compared with preoperative angiography.

RESULTS

We identified 140 patients, with 147 aneurysms, who met our inclusion criteria. Five patients had bilateral aneurysms. There were 31 male patients in our cohort (21.9%) and the mean average age was 56.2 ± 13.7 years. Sixty-seven aneurysms arose from the communicating, 58 from the ophthalmic, and 22 from the clinoidal segments. At last follow-up (mean, 22.3 months) 116 aneurysms were completely occluded (78.3%). On the most recent angiogram, 7 ophthalmic (5.3%), 20 posterior communicating (42.6%), 0 anterior choroidal (0%), and 2 anterior cerebral arteries (14.3%) were completely occluded. Reduced vessel caliber was seen in 11 ophthalmic (8.3%), 3 posterior communicating (6.4%), 0 anterior choroidal, and 6 anterior cerebral arteries (42.9%). One patient died during follow-up.

CONCLUSIONS

The side branch occlusion rate was 20% and included ophthalmic, posterior communicating, and anterior cerebral arteries. Consistent with other studies, we did not see occlusion of the anterior choroidal artery.

Complication Risk Factors in Anterior Choroidal Artery Aneurysm Treatment

OBJECT

The anterior choroidal artery (AChoA) is a rare location for intracranial aneurysms. The treatment of these aneurysms may be challenging due to the risk of occlusion of such a small and eloquent artery as the AChoA. We aimed to evaluate the risk factors for complications in AChoA aneurysm treatment.

METHODS

We retrospectively analyzed 47 consecutive AChoA aneurysms in 40 patients treated in our institution from 1999 and 2014 by endovascular means (87%) or surgical clipping (13%). Minor (transient or minor neurological deficits) and major complications (severe permanent neurological deficits or death) were systematically recorded. The influence of patient age, sex, aneurysm size, neck size, shape, dome-to-neck ratio and treatment technique on the occurrence of procedure-related complications was evaluated.

RESULTS

Of the patients 11 experienced procedure-related complications (5 major, 6 minor). Aneurysms with multilobed shape were significantly associated with a higher procedure-related complication rate. There was a tendency for higher major procedure-related complication rate in small volume aneurysms. We did not find any association between the other factors analyzed and occurrence of procedure-related complications.

CONCLUSION

Treatment of AChoA aneurysms has an acceptable complication risk. We did not find any significant differences between surgical and endovascular treatment in terms of procedure-related complication rates. Multilobed aneurysms were significantly associated with a higher procedure-related complication rate.

Patency of the posterior communicating artery following treatment with the Pipeline Embolization Device

OBJECTIVE

The Pipeline Embolization Device (PED) has become an effective treatment strategy for some cerebral aneurysms. Concerns regarding the patency of branch arteries have been raised. The objective of this study was to assess the patency of the posterior communicating artery (PCoA) following treatment of PCoA aneurysms using the PED.

METHODS

All patients with PCoA aneurysms treated with the PED who had angiographic follow-up were retrospectively identified. The patency of the PCoA at follow-up was evaluated by 2 authors who were not involved in the intervention. Univariate and multivariate analyses were performed to identify factors associated with the following: 1) PCoA patency versus no or diminished flow, and 2) PCoA patency and diminished flow versus PCoA occlusion.

RESULTS

Thirty patients with an angiographic follow-up of 6 months were included. Aneurysm obliteration was achieved in 25 patients (83.3%). The PCoA was patent in 7 patients (23.3%), had diminished flow in 7 patients (23.3%), and was occluded in 16 patients (53.3%). In the univariate analysis of outcome, there was a trend for aneurysms with incomplete occlusion, aneurysms not previously treated, those with presence of a fetal PCoA, and those with an artery coming from the aneurysm to have higher odds of the PCoA remaining patent. In univariate and multivariate analyses of factors associated with outcome, fetal PCoA and presence of an artery coming from the aneurysm were associated with the PCoA remaining open with or without diminished flow. No patients had symptoms related to PCoA occlusion.

CONCLUSIONS

Occlusion and diminished flow through the PCoA is common following PED treatment of PCoA aneurysms. However, it is clinically insignificant in most cases.

Quantitative flow measurement after placing a flow diverter for a distal internal carotid artery aneurysm

Objectives

To evaluate the differences in arterial flow after flow diverter placement using quantitative flow measurements based on digital subtraction angiography (DSA).

Methods

Between November 2013 and November 2015, all patients who had flow diverters placed for distal internal carotid artery (ICA) aneurysms were reviewed. Patients in whom the stent was placed across the ostia of the ophthalmic artery (OphA) and anterior choroidal artery (AChA) were enrolled. Five regions of interest were selected: the proximal ICA (as a reference), terminal ICA, middle cerebral artery (MCA), anterior cerebral artery (ACA), OphA, and AChA. The values of the peak, time-to-peak (TTP), and area under the curve (AUC) were analyzed using a quantitative DSA technique.

Results

The study enrolled 13 patients. The quantitative flow analysis showed improved flow in the terminal ICA (peak and AUC, p=0.036 and p=0.04, respectively), MCA (AUC, p=0.023), and ACA (AUC, p=0.006), and decreased flow in the OphA (peak and AUC, p=0.013 and p=0.005, respectively) and AChA (peak and subtracted TTP, p=0.023 and p=0.050, respectively) after flow diverter placement. Larger aneurysm volume was significantly correlated with decreased OphA flow after the procedure (peak and AUC, p=0.049 and p=0.037, respectively). Larger aneurysm volume also had a marginal correlation with increased distal ICA flow after the procedure, but this did not reach significance (peak and AUC, p=0.195 and p=0.060, respectively).

Conclusions

Without using extra contrast medium or radiation dosages, color-coded DSA enables quantitative monitoring of the cerebral circulation after flow-diverting treatment.

Flow changes in the posterior communicating artery related to flow-diverter stents in carotid siphon aneurysms

BACKGROUND

Flow-diverter stent (FDS) placement for treatment of intracranial aneurysms can cause flow changes in the covered branches.

OBJECTIVE

To assess the impact of the treatment of carotid siphon aneurysms with FDS on the posterior communicating artery (PComA) flow.

MATERIALS AND METHODS

Between February 2011 and January 2015, 125 carotid siphon aneurysms were treated with FDS. We retrospectively analyzed all cases with PComA ostial coverage. The circle of Willis anatomy was also studied as the flow changes in PComA postoperatively and during angiographic follow-up. Data from neurological examination were also collected.

RESULTS

Eighteen aneurysms of the carotid siphon in 17 patients were treated with FDS covering the ostium of the PComA. Based on the initial angiography, patients were divided into two groups: the first with a P1/PComA size ratio >1 (10 cases) and the second with a ratio ≤1 (8 cases). Follow-up angiography (mean time of 10 months) showed 90% of PComA flow changes in group 1 but only 12.5% in group 2. There was a significant difference between the two groups (p=0.002). Nevertheless, no patient had new symptoms related to these flow changes during the follow-up period.

CONCLUSIONS

In our experience, covering the PComA by FDS when treating carotid siphon aneurysms appeared safe and the P1/PComA ratio is a good predictor of flow changes in PComA.

Patency of anterior circulation branch vessels after Pipeline embolization: longer-term results from 82 aneurysm cases

OBJECTIVE The Pipeline Embolization Device (PED) has become increasingly used for the treatment of intracranial aneurysms. Given its high metal surface area coverage, there is concern for the patency of branch vessels that become covered by the device. Limited data exist regarding the patency of branch vessels adjacent to aneurysms that are covered by PEDs. The authors assessed the rate of intracranial internal carotid artery, anterior circulation branch vessel patency following PED placement at their institution. METHODS The authors retrospectively reviewed the records of 82 patients who underwent PED treatment between 2009 and 2014 and in whom the PED was identified to cover branch vessels. Patency of the anterior cerebral, posterior communicating, anterior choroidal, and ophthalmic arteries was evaluated using digital subtraction angiography preoperatively and postoperatively after PED deployment and at longer-term follow-up. RESULTS Of the 127 arterial branches covered by PEDs, there were no immediate postoperative occlusions. At angiographic follow-up (mean 10 months, range 3-34.7 months), arterial side branches were occluded in 13 (15.8%) of 82 aneurysm cases and included 2 anterior cerebral arteries, 8 ophthalmic arteries, and 3 posterior communicating arteries. No cases of anterior choroidal artery occlusion were observed. Patients with branch occlusion did not experience any neurological symptoms. CONCLUSIONS In this large series, the longer-term rate of radiographic side branch arterial occlusion after coverage by a flow diverter was 15.8%. Terminal branch vessels, such as the anterior choroidal artery, remained patent in this series. The authors' series suggests that branch vessel occlusions are clinically silent and should not deter aneurysm treatment with flow diversion.

Predictive modeling and in vivo assessment of cerebral blood flow in the management of complex cerebral aneurysms

Cerebral aneurysms are weakened blood vessel dilatations that can result in spontaneous, devastating hemorrhage events. Aneurysm treatment aims to reduce hemorrhage events, and strategies for complex aneurysms often require surgical bypass or endovascular stenting for blood flow diversion. Interventions that divert blood flow from their normal circulation patterns have the potential to result in unintentional ischemia. Recent developments in computational modeling and in vivo assessment of hemodynamics for cerebral aneurysm treatment have entered into clinical practice. Herein, we review how these techniques are currently utilized to improve risk stratification and treatment planning.

Role of terminal and anastomotic circulation in the patency of arteries jailed by flow-diverting stents: from hemodynamic changes to ostia surface modifications

OBJECTIVE The outcome for jailing arterial branches that emerge near intracranial aneurysms during flow-diverting stent (FDS) deployment remains controversial. In this animal study, the authors aimed to elucidate the role of collateral supply with regard to the hemodynamic changes and neointimal modifications that occur from jailing arteries with FDSs. To serve this purpose, the authors sought to quantify 1) the hemodynamic changes that occur at the jailed arterial branches immediately after stent placement and 2) the ostia surface values at 3 months after stenting; both parameters were investigated in the presence or absence of collateral arterial flow. METHODS After an a priori power analysis, 2 groups (Group A and Group B) were created according to an animal flow model for terminal and anastomotic arterial circulation; each group contained 7 Large White swine. Group A animals possessed an anastomotic-type arterial configuration to supply the territory of the right ascending pharyngeal artery (APhA), while Group B animals possessed a terminal-type arterial configuration to supply the right APhA territory. Subsequently, all animals underwent FDS placement, thereby jailing the right APhAs. Mean flow rates and velocities inside the jailed branches were quantified using time-resolved 3D phase-contrast MR angiography before and after stenting. Three months after stent placement, the jailed ostia surface values were quantified on scanning electron micrographs. The data were analyzed using descriptive statistics and group comparisons with parametric and nonparametric tests. RESULTS The endovascular procedures were feasible, and there were no findings of in situ thrombus formation on postprocedural optical coherence tomography or ischemia on postprocedural diffusion-weighted imaging. In Group A, the mean flow rate values at the jailed right APhAs were reduced immediately following stent placement as compared with values obtained before stent placement (p = 0.02, power: 0.8). In contrast, the mean poststenting flow rates for Group B remained similar to those obtained before stent placement. Three months after stent placement, the mean ostia surface values were significantly higher for Group B (527,911 ± 306,229 μm²) than for Group A (89,329 ± 59,762 μm²; p < 0.01, power: 1.00), even though the initial dimensions of the jailed ostia were similar between groups. A statistically significant correlation was found between groups (A or B), mean flow rates after stent placement, and ostia surface values at 3 months. CONCLUSIONS When an important collateral supply was present, the jailing of side arteries with flow diverters resulted in an immediate and significant reduction in the flow rate inside these arteries as compared with the prestenting values. In contrast, when competitive flow was absent, jailing did not result in significant flow rate reductions inside the jailed arteries. Ostium surface values at 3 months after stent placement were significantly higher in the terminal group of jailed arteries (Group B) than in the anastomotic group (Group A) and strongly correlated with poststenting reductions in the velocity value.

Flow diversion of bifurcation aneurysms is more effective when the jailed branch is occluded: an experimental study in a novel canine model

BACKGROUND

Flow diverters (FDs) are increasingly used for bifurcation aneurysms. Failure of aneurysm occlusion may be caused by residual flow maintaining patency of the jailed branch along with the aneurysm. Our aim was to test whether endovascular occlusion of the jailed branch could improve efficacy of flow diversion of bifurcation aneurysms.

MATERIALS AND METHODS

Sixteen wide-necked lingual-carotid artery bifurcation aneurysms were created in eight canines. Patent aneurysms were randomly allocated 4 weeks later to flow diversion combined with jailed branch occlusion using coils and/or Onyx (n=6) or flow diversion alone (n=8). Angiographic results of aneurysm occlusion at 3 months were scored using an ordinal scale. Pathology specimens were photographed and neointimal coverage estimated using a semiquantitative scoring system.

RESULTS

Fourteen aneurysms were patent at 1 month. FD deployment was successful in all cases but, at 3-month follow-up, three devices had prolapsed into the aneurysm. None of the bifurcation aneurysms treated with FD alone were occluded at 3 months. Endovascular branch occlusion combined with flow diversion significantly improved aneurysm occlusion rates compared with flow diversion alone (median angiographic scores 2 vs 0: p=0.0137). Flow-limiting parent vessel stenosis was not observed in any arteries. Devices were covered with thick neointima in most cases, but patent aneurysms were associated with leaks or holes in the neointima covering the aneurysm neck.

CONCLUSIONS

Treatment failures following flow diversion of bifurcation aneurysms can be caused by persistent flow to the jailed branch. Branch occlusion combined with flow diversion may improve angiographic occlusion scores of a canine bifurcation aneurysm model.

Very late ischemic complications in flow-diverter stents: a retrospective analysis of a single-center series

OBJECTIVE The authors evaluate the rate and discuss the pathomechanisms of very late (≥ 4-month) ischemic complications after flow-diverter stent (FDS) placement for intracranial aneurysms. METHODS The authors retrospectively reviewed the clinical data of the patients treated at Pitié-Salpêtrière Hospital between January 2010 and September 2014, who underwent FDS placement for intracranial aneurysm. The patients received dual-antiplatelet therapy (clopidogrel and aspirin) 5 days before and 3-6 months after the procedure and then aspirin alone for 6-9 months. An ischemic complication was defined as a sudden focal neurological deficit documented on diffusion-weighted images. RESULTS Eighty-six consecutive patients were included. Three (3.5%) patients treated with the Pipeline embolization device experienced a delayed acute ischemic stroke (2 cases of perforator/side-wall branch infarction and 1 case of thromboembolic stroke) with an average delay of 384 days (4 months, 20 months, and 13 months, respectively). The aneurysm locations were the left superior cerebellar artery, the right anterior choroid artery, and the left internal carotid artery (paraclinoid segment), respectively. The complications occurred after the patients had completed the antiaggregation protocol, except for Patient 1, who was receiving aspirin alone because of a spontaneous hematoma. At the acute phase, no in-stent thromboses were found on digital subtraction angiography. In Patient 2, the treated anterior choroid artery was occluded 20 months after the procedure. In Patient 3, a focal stenosis (approximately 40%) of the distal aspect of the FDS, probably caused by intimal hyperplasia, was seen. CONCLUSIONS Very late ischemic complications after FDS treatment were observed in 3.5% of the cases in the authors' series, some of which occurred as late as more than 1 year after placement.

Posterior Inferior Cerebellar Artery Patency after Flow-Diverting Stent Treatment

BACKGROUND AND PURPOSE

The rate of PICA occlusion after flow-diverting stent placement for vertebral and vertebrobasilar artery aneurysms is not known. The purpose of this study is to determine the medium-term rate of PICA patency and risk factors for occlusion after such aneurysm treatment.

MATERIALS AND METHODS

Patients were identified who had vertebral or vertebrobasilar artery aneurysms and who were treated by placing a flow-diverting stent across the PICA ostium. Demographic and procedural factors associated with stent placement were recorded. Patency of the PICA was evaluated immediately after stent placement and on follow-up angiography.

RESULTS

Thirteen patients with vertebral or vertebrobasilar artery aneurysms were treated in the study period, of whom 4 presented with subarachnoid hemorrhage. The average number of devices that spanned the PICA ostium was 1.77 (range, 1-3), with no immediate PICA occlusions. There were no postoperative strokes in the treated PICA territory, although there was 1 contralateral PICA-territory stroke of unclear etiology without clinical sequelae. In 11 patients with follow-up angiography at a mean of 10.6 months (range, 0.67-27.9 months), the PICA patency rate remained 100%.

CONCLUSIONS

Flow-diverting stent placement across the PICA ostium in the treatment of vertebral and vertebrobasilar artery aneurysms may not result in immediate or midterm PICA occlusion.

Endovascular treatment of ophthalmic artery aneurysms: ophthalmic artery patency following flow diversion versus coil embolization

BACKGROUND AND PURPOSE

The Pipeline Embolization Device (PED) has been shown to effectively treat complex internal carotid artery aneurysms while maintaining patency of covered side branches. The purpose of this retrospective matched cohort study is to evaluate the effect of flow diversion on the patency of the ophthalmic artery when treating ophthalmic artery aneurysms.

METHODS

A retrospective review of our prospectively collected institutional database identified 19 ophthalmic artery aneurysms treated with a PED. These were matched according to aneurysm diameter in a 1:2 fashion to ophthalmic artery aneurysms treated via coil embolization, although it is important to note that there was a statistically significance difference in the neck diameter between the two groups (p=0.045). Clinical and angiographic outcomes were recorded and analyzed.

RESULTS

On follow-up angiography, decreased flow through the ophthalmic artery was observed in 26% of the PED cohort and 0% of the coil embolization cohort (p=0.003). No ophthalmologic complications were noted in either cohort. Complete occlusion at 12 months was more common following PED treatment than coil embolization (74% vs 47%; p=0.089), although lower than reported in previous trials. This may be due to inflow into the ophthalmic artery keeping the aneurysm patent. Retreatments were more common following coil embolization than PED (24% vs 11%), but this was not significant (p=0.304). Permanent morbidity rates were not significantly different between the PED (11%) and coil embolization (3%) cohorts (p=0.255).

CONCLUSIONS

Our results suggest that ophthalmic artery aneurysms may be adequately and safely treated with either the PED or coil embolization. However, treatment with the PED carries a higher risk of impeding flow to the ophthalmic artery, although this did not result in clinical sequelae in the current study.