Awake craniotomy in patients with arteriovenous malformation: A systematic review and meta­analysis.

The present systematic review aimed to identify all the available literature on awake craniotomy (AC) in patients with arteriovenous malformation (AVM) in order to evaluate its safety, risks, benefits and effectiveness. All available literature on AC in patients with AVM was collected and evaluated in an aim to provide a better understanding of its safety, associated risks and benefits. A systematic search for studies employing AC in patients with AVM was conducted using the PubMed, Scopus and ScienceDirect databases without restrictions on the year of publication, language, or study design, from inception up to May 30, 2021. A total of 11 studies published between 2004 and 2021 with 106 patients who underwent ACs were considered eligible. The rate of complete resection was 93% [95% confidence interval (CI), 82 to 100%; I2 0%]. The intraoperative complication rate was 21% (95% CI, 1 to 41%; I2 55%) and the post-operative complication rate was 33% (95% CI, 19 to 48%; I2 40%). During follow-up, the complication rate was 6% (95% CI, 1 to 10%; I2 30%). The post-operative complication rate was higher in the Spetzler-Martin grade (SMG) III-V group (31%; 95% CI, 21 to 42%; I2 46%) than in the SMG I-II group (12%; 95% CI, 2 to 22%; I2 0%). Similarly, the follow-up complication rate was higher in the SMG III-V group (9%; 95% CI, 2 to 16%; I2 34%) than in the SMG I-II group (0%; 95% CI, 0 to 4%; I2 0%). On the whole, the present study provides preliminary evidence to indicate that AC is a possible and useful option for the resection of AVM in selected patients. Well-designed future studies with long-term follow-up are required however, to investigate various aspects of safety and provide solid data for AC in patients with AVM.

Initiation of mechanical thrombectomy in an insular setting with helicopter transfer: a 2-year experience from the first, complete, tertiary stroke center in the Caribbean.

BACKGROUND: This is the first cohort study of patients treated with mechanical thrombectomy (MT) for acute ischemic stroke in the French West Indies, with a mothership center and helicopter transfer. OBJECTIVE: To describe the population and to evaluate imaging, clinical, and time metric outcomes, in order to assess the feasibility and adjust the territorial organization. METHODS: In this observational study, we retrospectively analyzed our prospectively collected data of a population of consecutive patients treated with MT for anterior and posterior circulation large vessel occlusions. Primary outcome was 3-month functional independence (modified Rankin Scale score ≤2). Secondary outcomes included aerial and terrestrial times of arrival, in-hospital delays, demographics, imaging and clinical data at onset, discharge, and at 3 months. We compared the results of the mothership and drip-and-ship paradigms. RESULTS: Between January 2020 and December 2021, 223 patients were included (74% mothership, 26% drip-and-ship). Mean National Institutes of Health Stroke Scale (NIHSS) score of the population was 16 before MT, with significant reduction (NIHSS score 6) at discharge (9 mothership, 12 drip-and-ship, P=0.025). There was significant difference in onset-to-operation room times among the two centers (335 min mothership, 500 min drip-and-ship, P=0.004). Successful recanalization (modified Thrombolysis in Cerebral Infarction score 2b-3) was 80.3%. Functional independence at 3 months was 35%, symptomatic intracranial hemorrhage was 11%, and the complication rate was 9.4%, all without statistically significant difference between the two groups. CONCLUSION: The population has distinct risk factors. MT with helicopter transfer is feasible in the French West Indies. Reduction of prehospital and in-hospital times is mandatory; evaluation of the territorial strategy is underway, to avoid over-selection of transferred patients.

Selective arterial temporary flow arrest with balloons during transvenous embolization for the treatment of brain arteriovenous malformations: a feasibility study with MRI-monitored adverse events.

BACKGROUND: The technique of endovascular transvenous embolization for brain arteriovenous malformations (AVMs) has emerged in the last 8 years as a very promising therapeutic alternative for otherwise incurable cases. Selective temporary flow arrest during transvenous endovascular embolization (TFATVE) is a novel adaptation of our previously described transvenous approach, which employs hyper-compliant balloons intra-arterially for the selective occlusion of arterial feeders during ethylene vinyl copolymer (EVOH) injection, in order to reduce intra-nidal pressure and increase nidi occlusion rates. METHODS: We performed a feasibility study of the TFATVE technique between January 2016 and April 2020. Consecutive patients were included. All patients had at least one axial brain MRI or CT in the first 48 hours following intervention, and at least one brain MRI scan within the first postoperative month, in order to detect both silent and clinically evident adverse events. Patients' demographics, angio-architectural characteristics, total injection and procedure times, angiographic and clinical outcomes were analyzed. RESULTS: 22 patients underwent TFATVE during transvenous endovascular treatment of brain AVMs. Among them, 86.4% were high Spetzler-Martin's grade. Good clinical outcome (modified Rankin Scale <2) was achieved in 95.5% of the cases, with 0% of procedure-related mortality and 4.5% of clinically significant, procedure-related morbidity. Total occlusion of the nidus was achieved in >90% of the cases at the end of the procedure and angiographic stability was achieved in all cases; 100% of the cases had angiographic cure at follow-up. CONCLUSIONS: TFATVE seems a safe and effective technique when conducted in carefully selected patients in highly specialized centers.

Review on the current treatment status of vein of Galen malformations and future directions in research and treatment.

INTRODUCTION: Vein of Galen malformations (VOGMs) represent a rare pathologic entity with often catastrophic natural history. The advances in endovascular treatment in recent years have allowed for a paradigm shift in the treatment and outcome of these high-flow shunts, even though their pathogenetic mechanisms and evolution remain in part obscure. AREAS COVERED: The overall management of VOGMs requires a tailored case-to-case approach, starting with in utero detection and reserving endovascular treatment for indicated cases. Lately, the advances in translational research with whole-genome sequencing and the coupling with cellular-level hemodynamics attempt to shed more light in the pathogenesis and evolution of these lesions. At the same time the advances in endovascular techniques allow for more safety and tailored technical strategy planning. Furthermore, the advances in MRI techniques allow a better understanding of their vascular anatomy. In view of these recent advances and by performing a PUBMED literature review of the last 15 years, we attempt a review of the evolutions in the imaging, management, endovascular treatment and understanding of underlying mechanisms for VOGMs. EXPERT OPINION: The progress in the fields detailed in this review appears very promising in better understanding VOGMs and expanding the available therapeutic arsenal.

Distal mechanical thrombectomy for very eloquent M3 branches with a new, adjustable diameter clot retriever: A technical note.

Distal thrombectomy may be considered in selected patients harboring acute occlusion of distal arterial branches, supplying very eloquent brain areas. In these cases navigation and deployment in tortuous, fragile and very small-caliber arteries is usually involved, potentially increasing the risk of per-procedural vessel wall perforation. We report a case of distal recanalization in a right-handed, fourty-year-old woman with left M3 occlusion, with the use of a novel device with manually adapted, gradual expansion, navigated through a 0.013-inch microcatheter, called the Tigertriever-13 [RapidMedical, Yokneam, Israel]. The device was deployed and retrieved with minimal alteration-straightening of the M3 vessels and complete recanalization was achieved. The patient achieved NIHSS 0 in less than 24 h.

Intra-arterial in-situ bevacizumab injection effect on angiogenesis. Results on a swine angiogenesis model.

BACKGROUND AND PURPOSE: In this study we tested the effect of antiangiogenics on a swine angiogenesis model that shares some brain AVM histological characteristics. The objective was to determine bevacizumab effects on retia volumes and on vessels' wall. MATERIALS AND METHODS: Fifteen pigs were divided into 3 groups: Five animals served as controls (group A), 5 animals underwent endovascular left external and common carotid artery occlusion (group B) and 5 animals underwent the same procedure and had an intra-arterial in-situ injection of bevacizumab (groupC) 2 months after the occlusion. A DSA associated with 3D-rotational angiography was performed at day 0 and at 3 months in all groups in order to measure rete mirabile volumes. The animals were sacrificed at 3 months and the retia were harvested for pathological and immunohistochemistry examinations. RESULTS: All VEGF-A receptors were blocked at the site of injection and there was a local enhanced endothelial proliferation and apoptosis. The volume of the retia remained unchanged after the bevacizumab injection. Retia vessels presented comparable media thickness, higher endothelial proliferation and apoptosis after the anti-VEGF injection. CONCLUSION: A single in-situ injection of bevacizumab in this swine angiogenesis model showed no change in retia volume and an extensive blockage of VEGF receptors at the site of injection one month later. Rete mirabile vessels presented comparable media thickness, higher endothelial proliferation and apoptosis after the anti-VEGF injection, suggesting that bevacizumab antiangiogenic effect does not fragilize vessel wall. More studies are needed to confirm these preliminary insights of in-situ antiangiogenic effect on vascular malformations.

Neurovascular devices for the treatment of intracranial aneurysms: emerging and future technologies.

Introduction: Despite numerous advances in the endovascular treatment of intracranial aneurysms (IAs), treatment in cases of wide-neck, complex configurations or branching locations remains challenging. Apart from the paradigm shift introduced by flow diverters, several other devices have seen the light or are under development in order to address these challenges.Areas covered: We performed a review of the novel implantable endovascular devices which have been introduced for the treatment of IAs, from 1 January 2014 to 1 September 2019, excluding classic flow diverter and intracranial stent designs.Expert opinion: Alternative designs have been proposed for the treatment of IAs at branching positions, which do not jail the side branches, with or without flow diversion effect, most of which with good initial outcomes. Endosaccular devices have also been proposed, some of which with lower initial total occlusion rates. Alternative materials such as biopolymers have also been proposed and are under bench research. Despite the challenges in the exploitation of some of the new devices, most of them seem to provide solutions to some current technical shortcomings. The exploitation of the biological phenomena and the physical properties of the devices will allow us to expand the therapeutic armamentarium for more complex IA cases.

Braided stents and their impact in intracranial aneurysm treatment for distal locations: from flow diverters to low profile stents.

INTRODUCTION: Intracranial aneurysms in distal locations are sometimes difficult to treat due to their branching locations and the presence of blister-like or very wide-necked aneurysms. Braided intracranial stents, including flow diverters (FDs) and low-profile braided intracranial stents (LPBSs) may provide additional advantages, due to their flow-diverting properties. AREAS COVERED: The use of FDs in off-label, distal intracranial locations has been increasing with promising outcomes and has given rise to the LPBS, which has less flow-diverting properties, allowing for easier use in distal branching sites through 0.017' microcatheters. These devices have shifted the interest from the aneurysm's sac filling to the regional remodeling through the effect of flow diversion. The purpose of this article is to discuss their functionality, safety, performance, and perspectives through a critical review of important publications of the last 11.5 years (January 2007 to July 2018) on the use of these devices at and beyond the circle of Willis. EXPERT OPINION: FDs modify the regional anatomy thus careful pre-procedural consideration of the regional hemodynamic equilibrium is mandatory, as well as effective antiplatelet regimen. LPBSs provide moderate flow-diversion effect, which may be an advantage, especially for very distal and small aneurysms.

Curative endovascular treatment for low-grade Spetzler-Martin brain arteriovenous malformations: a single-center prospective study.

BACKGROUND: The treatment of low grade Spetzler-Martin (SM) brain arteriovenous malformations (AVMs) has been debated in unruptured cases. Nevertheless, in clinical practice there are cases where treatment is preferred; in these cases a very low complication rate is mandatory. In ruptured cases, early and complete obliteration of the nidus is the preferred strategy. OBJECTIVE: To achieve curative embolization, ideally in a single session, by dual microcatheterization techniques with arterial and/or venous access, according to the angioarchitecture. MATERIALS AND METHODS: This is a prospective, single-center study carried out between January 2008 and January 2016. Patients with ruptured and unruptured brain AVMs, with SM grades I and II, treated by endovascular means, were included. Demographics, clinical presentation, angioarchitecture, and procedure-related complications were analyzed. Angiographic and clinical results were reported. RESULTS: Seventy-three patients, aged 40.5±17.8 years, were included. More than 60% of the patients presented with ruptured AVMs. Initial SM grades were I for 22% and II for 78% of the patients. Preprocedural modified Rankin Scale (mRS) score was 0-2 for 53 (72.6%), 3 for 12 (16.4%), 4 for 5 (6.8%) and 5 for 3 (4.1%) patients. Procedure-related morbidity was 2.7% and procedure-related mortality was 0%. Ninety percent (90.5%) of the patients were independent in their everyday lives (mRS score 0-2) at 6 months. In all but one case (95%) the embolization was curative. CONCLUSION: Stand-alone endovascular treatment for SM grade I and II brain AVMs seems safe and effective, allowing for complete obliteration of the nidus, with low complication rates. A study of larger cohorts is needed.

Comparison of stents used for endovascular treatment of intracranial aneurysms.

INTRODUCTION: Stent-assisted coiling (SAC) has widened indications of endovascular treatment of intracranial aneurysms (wide-neck, fusiform aneurysms); moreover, it is associated with more stable anatomical results. Besides the development of other techniques such as flow diverter stents, bifurcation stents, or intrasaccular flow disruptors, SAC remains one of the most used endovascular techniques because it provides good clinical and anatomical results for most aneurysms. Several devices based on the same principle are available and have undergone many adaptations and developments over 20 years of intracranial stenting. AREAS COVERED: The purpose of this article is to review and compare intrinsic properties of available devices and their anatomical and clinical performance. EXPERT COMMENTARY: Based on this review and our experience of SAC, we will discuss the behavior and performance of those devices in different anatomic and clinical situations.

Influence of Anatomic Changes on the Outcomes of Carotid Siphon Aneurysms After Deployment of Flow-Diverter Stents.

BACKGROUND: Flow-diverter stent (FDS) deployment can cause morphological and hemodynamic changes in the carotid siphon (CS), influencing the occlusion rate of aneurysms in this location. OBJECTIVE: To evaluate morphological changes to the CS after FDS deployment and their relationship with the rate of occlusion of intracranial aneurysms. METHODS: A cohort of 183 patients with CS aneurysms were treated by deployment of Pipeline® FDS (Medtronic Inc, Dublin, Ireland). Their CSs were classified as type U, V, C, or S, depending on morphology. The posterior and anterior bend angles were measured on strict lateral cerebral angiogram with digital subtraction before FDS deployment, immediately after deployment, and at 6 mo. Differences between angles were analyzed to identify any correlations with rates of aneurysm occlusion, using the O'Kelly-Marotta classification. RESULTS: FDS deployment was associated with immediate changes in CS morphology. The mean anterior angle increased from 3.97 ± 25.06° to 22.05 ± 25.18° (P < .001) and the mean posterior angle increased from 71.98 ± 31.27° to 79.43 ± 31.80° (P < .001). Multivariate analysis revealed a progressive, statistically significant increase in frequency of complete (grade D) occlusion at 6-mo follow-up with increasing anterior bend angle (prevalence ratios (PR) = 1.42 for increases between 5.3° and 12°, P = .017; PR = 1.56 for increases between 12.1° and 27.6°, P = .002; PR = 1.83 for increases >27.6°, P < .001, all vs increases <5.3°). CONCLUSION: FDS deployment induces changes in CS morphology. Specifically, increases in mean anterior angle are associated with better radiological results on 6-mo follow-up digital subtraction angiography.

Safety and effectiveness of the Low Profile Visualized Intraluminal Support (LVIS and LVIS Jr) devices in the endovascular treatment of intracranial aneurysms: results of the TRAIL multicenter observational study.

BACKGROUND AND PURPOSE: To evaluate the safety and effectiveness of the low-profile braided intracranial stents called the Low Profile Visualized Intraluminal Support (LVIS) devices for stent-assisted coil embolization of wide-necked intracranial aneurysms. MATERIALS AND METHODS: This was a prospective, multicenter, observational study of unruptured and ruptured intracranial aneurysms treated with the LVIS devices. Imaging and clinical data were independently analyzed respectively by CoreLab and Clinical Event Committee. Primary endpoints were clinical safety, effectiveness, and angiographic stability of the results at 6 and 18 months. RESULTS: Ten centers participated in the study; 102 patients were included and 90 patients (42.2% men, 57.8% women) were eventually analyzed, among which 27 (30.0%) had multiple aneurysms. Twenty-three (25.6%) were ruptured aneurysms, four of which (4.4%) were treated in the acute phase. One aneurysm was treated per patient; 92 LVIS and LVIS Jr devices were placed overall. The total aneurysm occlusion rate was 91.0% on immediate post-procedure angiograms, which remained unchanged at 6-month follow-up and was 92.4% at 18-month follow-up. One patient (1.1%) underwent retreatment between 6 and 18 months of follow-up. A modified Rankin score of 0 was documented for most cases immediately after the procedure (86.7%) and at 6-month (86.8%) and 18-month (83.3%) follow-up. The overall permanent morbidity rate at 18 months was 5.6% and the overall rate of events with sequelae related to the stent was 2.2%. The 18-month procedure-related mortality rate was 3.3%. No patient was deemed to require retreatment at 18-month follow-up. CONCLUSION: The LVIS/LVIS Jr endovascular devices are safe and effective in the treatment of ruptured and unruptured intracranial aneurysms, with acceptable complication rates, very high immediate total occlusion rates, and stable angiographic results.

Transvenous Curative Embolization of Cerebral Arteriovenous Malformations: A Prospective Cohort Study.

BACKGROUND: Curative transvenous embolization is an emerging strategy for treatment of cerebral arteriovenous malformations (AVMs). OBJECTIVE: To assess contemporary outcomes of transvenous embolization as a stand-alone therapy for cerebral AVMs. METHODS: We prospectively followed 40 patients with 41 AVMs who underwent transvenous endovascular therapy between January 2008 and January 2015. Patient demographics, AVM characteristics, endovascular techniques used, angiographic results, clinical outcomes, and complications were assessed independently. RESULTS: Thirty-eight of 41 (92.6%) AVMs were anatomically cured. The mean patient age was 37.7 yr (range, 18-69 yr) and 55% were female. Twenty-seven (67.5%) patients presented with hemorrhage. The mean size of the AVM nidus was 2.8 ± 1.2 cm, and low Spetzler-Martin grade AVMs comprised 41.5% of lesions. The majority of patients were treated in 1 session (56%; n = 23). The mean follow-up period was 28.4 (range, 6-106 mo). There was 1 (2.5%) hemorrhagic complication related to microcatheter navigation and 1 (2.5%) venous infarction was observed without clinical consequences. At 6-mo follow-up, 1 (2.5%) patient had significant disability. There were no recurrences during the follow-up period. Overall mortality was 2.5% and procedure-related mortality was 0%. CONCLUSION: This prospective contemporary series demonstrates a high rate of complete AVM obliteration and excellent functional outcomes in patients with both ruptured and unruptured AVMs treated with transvenous embolization. This approach is promising and warrants further investigation as a treatment for select AVMs.

MRI in chronic groin pain: sequence diagnostic reliability compared to systematic surgical assessment.

OBJECTIVE: To determine the diagnostic reliability of magnetic resonance imaging (MRI) sequences in chronic groin pain (CGP) compared to surgery and try to propose a suitable MRI protocol. MATERIALS AND METHODS: Forty-three consecutive patients with resistant clinical CGP underwent a pre-surgical pelvis MRI. Eight MRI sequences were acquired: axial fast spin-echo T1-weighted (FSE T1), coronal FSE T1, axial-oblique (in symphysis plane) proton density weighted with fat saturation (PDFS), coronal PDFS, sagittal PDFS, axial FSE T1 with fat saturation and gadolinium enhancement (FSGE), coronal FSE T1 FSGE and axial FSE T1 with Valsalva maneuver (VM). These sequences were reviewed for pubic symphysis assessment, adductor longus (AL) tendon and abdominal wall (AW) injuries. The same surgeon operated on all of these patients (26 AL and 49 AW). Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative prospective value (NPV) and accuracy of each sequence and combinations for AL or AW injuries were calculated in comparison to surgical findings. RESULTS: One hundred ninety-two sequences were obtained. Coronal T1 FSGE and axial T1 VM proved to be the most reliable sequences (accuracy: 91.67% in AL and 83.33% in AW). The best sequence combination was coronal T1, axial PDFS, sagittal PDFS and axial T1 VM (accuracy: 77.78%; Se: 100.00%, Sp: 69.23%, PPV: 55.56%, NPV: 100.00%). CONCLUSION: MRI has 77.78% accuracy, 100.00% sensitivity, 69.23% specificity, 55.56% PPV and 100.00% NPV in evaluating CGP, with coronal T1-axial PDFS-sagittal PDFS-axial T1 VM as the optimal protocol in terms of diagnostic performance within a reasonable scan time. Diagnostic performance of MRI was examined in the evaluation of CGP using surgery as reference standard.

Evaluation of ischemic lesion prevalence after endovascular treatment of intracranial aneurysms, as documented by 3-T diffusion-weighted imaging: a 2-year, single-center cohort study.

OBJECTIVE Even though published data exist concerning the prevalence of ischemic lesions detected by diffusion-weighted imaging (DWI) following endovascular treatment of intracranial aneurysms, a single-center cross-evaluation of the different endovascular techniques has been lacking. The authors sought to prospectively evaluate the prevalence and clinical significance of ischemic lesions occurring after endovascular treatment of intracranial aneurysms and to compare the safety and effectiveness of a broad spectrum of currently accepted endovascular techniques in a single-center setting. METHODS This was a prospective cohort study involving consecutive patients treated for intracranial aneurysms exclusively by endovascular means, excluding treatments in the acute rupture phase, in a center featuring an endovascular-only treatment policy for intracranial aneurysms. All patients underwent MRI, including a 3-directional DWI sequence, before treatment, 24 hours postprocedure, and 6 months following endovascular embolization. Selective angiography was performed at 6 months' follow-up. RESULTS From January 2012 through December 2013, 164 aneurysms were treated in 128 consecutive patients. Endovascular techniques included coiling (14.6%), balloon-assisted coiling (20.1%), stent-assisted coiling (3.7%), low-profile stent-assisted coiling, flow diversion (38.4%), and very complex treatments (6.1%) involving 2 stents in Y or T configurations. On postprocedure MRI, the rates of occurrence of new DWI-positive lesions were 64.3% for coiling, 54.5% for remodeling, 61.1% for stent-assisted coiling, 53.7% for flow-diverting stents, and 75% for very complex treatments (p = 0.4962). The 6-month procedure-related morbidity and mortality rates were 6.25% and 0%, respectively. At 6 months' follow-up, 93% of the patients had modified Rankin Scale (mRS) scores of 0-2. Very complex treatments offered a higher complete occlusion rate (100%) than all other techniques (66.7%-88.9%). Age and length of procedure were independent factors for DWI lesion occurrence. The diameter of DWI lesions on 24-hour postprocedure MRI was positively correlated with mRS score at discharge. Among the DWI-positive lesions measuring less than 2 mm in diameter on the 24-hour MRI, 44.12% had regressed at 6 months. CONCLUSIONS Procedure-related DWI lesions are far more often encountered in silent forms than they are clinically evident. They do not seem to be significantly correlated with procedure-related complications, nor do they seem to impair clinical outcome, regardless of the endovascular technique. Small lesions (< 2 mm in diameter) may regress within 6 months. The use of the most adapted technique, in terms of aneurysm configuration, results in significant total occlusion rates, with acceptable safety.

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.

Jailed Artery Ostia Modifications After Flow-Diverting Stent Deployment at Arterial Bifurcations: A Scanning Electron Microscopy Translational Study.

BACKGROUND: Even though flow-diverting stents are being increasingly used to treat intracranial aneurysms, the fate of jailed side branches remains controversial, with recent clinical data contradicting finding of earlier animal studies that reported patency. OBJECTIVE: To quantify the surface area of the ostia after 3 months of jailing by flow-diverting stents as a more accurate means of patency evaluation. METHODS: Ten large white swine were stented by flow-diverting stents placed at common carotid-ascending pharyngeal arterial bifurcation sites. A dual antiplatelet regimen was initiated 72 hours before stenting and maintained during follow-up. Optical coherence tomography was used to search for per-procedural thrombus formation. Selective control digital subtraction angiography was performed 12 weeks post-stenting. Subsequently, the stented arterial segments were harvested en bloc and observed under scanning electron microscopy, photographed, and quantified. RESULTS: The absence of per-procedural thrombus formation was confirmed. All ostia were patent at 12 weeks (or 3 months) post stenting, with no angiographic or scanning electron microscopy-evident thrombus formation. The mean initial ostium surface was 2 048 617 ± 731 625 µm. At 3 months, the mean nonendothelialized ostium surface was 229 218 ± 140 172 µm, and mean endothelialized ostium surface was 1 819 399 ± 672 632 µm. A statistically significant difference (reduction) was observed between the initial and 12-week ostium surfaces (P < .001), with an significant statistical power (1.000). CONCLUSION: Jailed side branches remained patent after stenting, but the surface quantifications showed significant endothelial coverage, with a significant reduction of patent ostium surfaces at 12 weeks post-stenting. ABBREVIATIONS: APhA, ascending pharyngeal arteryCI, confidence interval3DRA, 3-dimensional rotational angiographyDSA, digital subtraction angiographyFDS, flow-diverting stentOCT, optical coherence tomographyOS, ostium surfaceSEM, scanning electron microscopy.

Intravascular optical coherence tomography for the evaluation of arterial bifurcations covered by flow diverters.

BACKGROUND AND OBJECTIVE: Due to its high spatial resolution, intravascular optical coherence tomography (OCT) has been used as a valid method for in vivo evaluation of several types of coronary stents at straight lumen and bifurcation sites. We sought to evaluate its effectiveness for flow diverting stents deployed in arterial bifurcation sites involving jailing of a side branch. METHODS: Four large white swine were stented with flow diverting stents covering the right common carotid artery-ascending pharyngeal artery bifurcation. After 12 weeks of follow-up the animals were evaluated by digital subtraction angiography and intravascular OCT and subsequently sacrificed. Neointimal thickness on the parent arteries and the free segments of the stent were measured. The stented arteries were harvested and underwent scanning electron microscopy (SEM) imaging. Ostia surface values were measured with OCT three-dimensional (3D) reconstructions and SEM images. RESULTS: All endovascular procedures and OCT pullback runs were feasible. Stent apposition was satisfactory on the immediate post-stent OCT reconstructions. At 12-week controls, all stents and jailed branches were patent. Mean neointimal thickness was 0.11±0.04 mm on the free segments of the stent. The mean ostia surface at 12 weeks was 319 750±345 533 µm2 with 3D-OCT reconstructions and 351 198±396 355 µm2 with SEM image-derived calculations. Good correlation was found for ostia surface values between the two techniques; the values did not differ significantly in this preliminary study. CONCLUSIONS: Intravascular OCT appears to be a promising technique for immediate and follow-up assessment of the orifice of arterial branches covered by flow diverting stents.

Role of terminal and anastomotic circulation in the patency of arteries jailed by flow-diverting stents: animal flow model evaluation and preliminary results.

OBJECTIVE The authors describe herein the creation of an animal model capable of producing quantifiable data regarding blood flow rate and velocity modifications in terminal and anastomotic types of cerebrofacial circulation. They also present the preliminary results of a translational study aimed at investigating the role of terminal and anastomotic types of circulation in arterial branches jailed by flow-diverting stents as factors contributing to arterial patency or occlusion. METHODS Two Large White swine were used to validate a terminal-type arterial model at the level of the right ascending pharyngeal artery (APhA), created exclusively by endovascular means. Subsequently 4 Large White swine, allocated to 2 groups corresponding to the presence (Group B) or absence (Group A) of terminal-type flow modification, underwent placement of flow-diverting stents. Blood flow rates and velocities were quantified using a dedicated time-resolved 3D phase-contrast MRA sequence before and after stenting. Three months after stent placement, the stented arteries were evaluated with digital subtraction angiography (DSA) and scanning electron microscopy (SEM). Patent (circulating) ostia quantification was performed on the SEM images. RESULTS Terminal-type flow modification was feasible; an increase of 75.8% in mean blood velocities was observed in the right APhAs. The mean blood flow rate for Group A was 0.31 ± 0.19 ml/sec (95% CI -1.39 to 2.01) before stenting and 0.21 ± 0.07 ml/sec (95% CI -0.45 to 0.87) after stenting. The mean blood flow rate for Group B was 0.87 ± 0.32 ml/sec (95% CI -1.98 to 3.73) before stenting and 0.76 ± 0.13 ml/sec (95% CI -0.41 to 1.93) after stenting. Mean flow rates after stenting showed a statistically significant difference between Groups A and B (Welch test). Mean and maximal blood velocities were reduced in Group A cases and did not decrease in Group B cases. Control DSA and SEM findings showed near occlusion of the jailed APhAs in both cases of anastomotic circulation (mean patent ostium surface 32,776 µm2) and patency in both cases of terminal-type circulation (mean patent ostium surface 422,334 µm2). CONCLUSIONS Terminal-type arterial modification in swine APhAs is feasible. Sufficient data were acquired to perform an a priori analysis for further research. Flow diversion at the level of the APhA ostium resulted in significant stenosis in cases of anastomotic circulation, while sufficient patency was observed in terminal-type circulation.

Transvenous Embolization in Pediatric Plexiform Arteriovenous Malformations.

BACKGROUND: Transvenous embolization is a developing concept for curative therapy of cerebral arteriovenous malformations (AVMs). The feasibility of this endovascular method has not been reported in children. OBJECTIVE: To report our experience treating pediatric AVMs with the transvenous approach (TVA). METHODS: A cohort of 7 pediatric patients (younger than 18 years of age) who underwent the TVA for cerebral AVMs between January 2012 and January 2014. The TVA was used alone or in conjunction with other arterial approaches in definitive embolization sessions. Patient demographics, AVM characteristics, clinical outcomes, and angiographic results were independently assessed. Pial arteriovenous fistulae and vein of Galen malformations were excluded. Control angiograms were obtained at 6 months, and curative treatment was determined by the anatomic obliteration of the nidus. RESULTS: All patients had anatomic exclusion of the AVM. The mean size was 2 ± 0.6 cm, and hemorrhage was the most common presentation (100%, n = 7). Most AVMs were deeply placed (71%, n = 5), and a proximal approach to the nidus was achieved in all cases. Transvenous embolization alone was performed in 3 patients (43%), whereas combined arterial and venous embolization was required in 4 patients (57%). The mean follow-up period was 20.2 ± 10.5 months. There were no hemorrhagic or thromboembolic events, and venous infarction was not documented. No recurrence was documented. CONCLUSION: This is the first report that demonstrates the feasibility of transvenous Onyx embolization of AVMs in the pediatric population. Such a technique may be considered in certain AVMs that meet anatomic criteria in which microsurgery and radiosurgery might not be indicated.