Most Promising Approaches to Improve Brain AVM Management: ARISE I Consensus Recommendations

Brain arteriovenous malformations (bAVMs) are complex, and rare arteriovenous shunts that present with a wide range of signs and symptoms, with intracerebral hemorrhage being the most severe. Despite prior societal position statements, there is no consensus on the management of these lesions. ARISE (Aneurysm/bAVM/cSDH Roundtable Discussion With Industry and Stroke Experts) was convened to discuss evidence-based approaches and enhance our understanding of these complex lesions. ARISE identified the need to develop scales to predict the risk of rupture of bAVMs, and the use of common data elements to perform prospective registries and clinical studies. Additionally, the group underscored the need for comprehensive patient management with specialized centers with expertise in cranial and spinal microsurgery, neurological endovascular surgery, and stereotactic radiosurgery. The collection of prospective multicenter data and gross specimens was deemed essential for improving bAVM characterization, genetic evaluation, and phenotyping. Finally, bAVMs should be managed within a multidisciplinary framework, with clinical studies and research conducted collaboratively across multiple centers, harnessing the collective expertise and centralization of resources.

Large, Wide-Neck, Side-Wall Aneurysm Treatment in Canines Using NeuroCURE: A Novel Liquid Embolic

BACKGROUND

Untreated intracranial aneurysms can rupture and result in high rates of morbidity and mortality. Although there are numerous approved endovascular aneurysm treatment devices, most require dual anti-platelet therapy, are minimally biocompatible, or are prone to recanalization. Neurovascular Controlled Uniform Rapid Embolic (NeuroCURE) is an innovative polymer gel material with long-term stability, biocompatibility, and hemocompatibility developed for the treatment of large, wide-neck aneurysms.

METHODS

Sidewall aneurysms were surgically created in 10 canines and NeuroCURE was injected through a 0.025 microcatheter under a single balloon inflation period. Aneurysm treatment was angiographically assessed post-embolization and pre-term with Raymond-Roy occlusion classification and a qualitative flow grade scale. Aneurysm neck stability and biocompatibility was histologically assessed to grade platelet/fibrin thrombus, percent endothelialization, and neointimal formation. Aneurysm sac stability was assessed by NeuroCURE sac content, inflammation, and neo-angiogenesis scales.

RESULTS

Explanted aneurysms exhibited a smooth surface at the aneurysm neck with nearly complete neointimal coverage at 3-months. By 6-months, neck endothelialization was 100% in all animals (average Raymond-Roy occlusion classification of 1.2), with no instances of aneurysm recanalization or parent vessel flow compromise. Biocompatibility assessments verified a lack of inflammatory response, neo-angiogenesis, and platelet/fibrin thrombus formation.

CONCLUSION

The NeuroCURE material promotes progressive occlusion of wide-necked side wall aneurysms over time without the need for dual antiplatelet agents. NeuroCURE also promotes neointimal tissue infill without dependence on thrombus formation and thus resists aneurysm recanalization. NeuroCURE remains a compelling investigational device for the treatment of intracranial aneurysms.

Material characterization of GPX®: A versatile in situ solidifying embolic platform technology

Endovascular embolization is a minimally invasive procedure during which blood flow to targeted tissues is selectively occluded. The list of clinical indications for embolization continues to expand. Liquid embolic agents are injectable compositions that transition into a solid or semi-solid form when introduced into blood vessels. The mechanism that triggers the liquid-to-solid transition is a key distinguishing feature of liquid embolic agents. GPX is a waterborne liquid embolic agent comprising oppositely charged polyelectrolytes: polyguanidinum and inorganic polyphoshate. In situ solidification is driven by electrostatic condensation of the polyelectrolytes, triggered by ionic strength differentials. We report in vitro characterization of the material properties of GPX, it is in vivo effectiveness in acute animal studies, and its potential for chemoembolization. The viscosity of GPX can be varied over a wide range by adjusting the polyguanidinium MW and/or concentration. Formulation of GPX with either tantalum microparticles (30 wt%) or iodinated radiocontrast agents (300 mgI ml^-1) did not significantly change the flow behavior of GPX; the viscosity was independent of shear rate and remained within a clinically practical range (80-160 cP). Formulation of GPX with doxorubicin substantially increased viscosity at low shear rates and resulted in a power law dependence on shear rate. High contrast and effective vascular occlusion were demonstrated in both swine kidneys and rete mirabile. Contrast from iodinated compounds was temporary, dissipating within hours. The doxorubicin in vitro release profile was linear over 90 days. The results demonstrate that GPX is a versatile liquid embolic platform that can be formulated with a wide range of viscosities injectable at clinically practical flow rates, with either transient or permanent contrast, and that can provide prolonged zero-order delivery of doxorubicin to embolized tissues.

De Novo dural arteriovenous fistulas after endovascular treatment: Case illustration and literature review

Intracranial dural arteriovenous fistulas (dAVF) account for nearly 10-15% of all arteriovenous malformations. Although the majority of dAVF are effectively cured after endovascular intervention, there are cases of dAVFs that may recur after radiographic cure. We present the case of a 69-year-old female with de novo formation of three dAVFs in different anatomic locations after successive endovascular treatments. The patient's initial dAVF was identified in the right posterior frontal convexity region and obliterated with transarterial and transvenous embolization. The patient returned eight years later due to left-sided pulsatile tinnitus and a new dAVF in the left greater sphenoid wing region was seen on angiography. This was treated with transvenous embolization with complete resolution. One year later, she developed left sided pulsatile tinnitus again and was found to have a left carotid-cavernous dAVF. This is the first case report to our knowledge of the formation of three de novo dAVFs over multiple years in distinct anatomical locations. We also review the literature regarding de novo dAVFs after endovascular treatment which includes 16 cases. De novo dAVF formation is likely due to numerous factors including changes in venous flow and aberrant vascular development. It is important to further understand the relationship between endovascular treatment and recurrent dAVF formation to prevent subsequent malformations.

Iatrogenic pseudoaneurysm of the middle meningeal artery during embolization of bilateral chronic subdural hematomas

Summary/AbstractMiddle meningeal artery embolization has become an important treatment option for chronic subdural hematomas. While the treatment is safe, we present a unique case of development of an iatrogenic middle meningeal artery pseudoaneurysm during endovascular embolization with use of a dual-lumen balloon catheter used for injection of a liquid embolic agent. A 62-year-old man on Coumadin for portal vein thrombosis presented to the hospital with headache and supratherapeutic INR. Imaging revealed bilateral acute on chronic subdural hematomas. Given his medical comorbidities he underwent endovascular middle meningeal artery embolization. During the embolization, angiography revealed a pseudoaneurysm of the middle meningeal artery related to use of a dual-lumen balloon catheter. This pseudoaneurysm was successfully treated with ethylene vinyl alcohol embolization. Intracranial pseudoaneurysm related to balloon catheter use is a rare cause of iatrogenic pseudoaneurysm and could lead to life-threatening intracranial bleeding. Therefore, recognition and timely treatment are important.

Translational Development of a Silk-Elastinlike Protein Polymer Embolic for Transcatheter Arterial Embolization

Locally blocking blood flow to tumors with embolic materials is the key to transcatheter arterial embolization for treating hepatocellular carcinoma. Current microparticle agents do not deeply penetrate target tissues and are compatible with a very limited selection of therapeutic agents. Silk-elastinlike protein polymers (SELPs) combine the solubility of elastin and the strength of silk to create an easily injected liquid embolic that transition into a solid depot amenable to loading with drugs, gene therapy agents, or biologics. SELP, injected as liquid solution, penetrates the vasculature before transitioning to a solid hydrogel. The objective of this manuscript is to evaluate SELP embolization, stability, and biocompatibility at 7-, 30-, and 90-day survival intervals in a porcine model. SELP embolics selectively block blood flow in the kidneys and livers, with no off-target infarctions. As assessed with angiography, SELP renal embolization exhibits decreasing persistence for the duration of the 90-day study period. There is an increased presence of microscopic SELP emboli in the renal setting, compared to Embosphere. Histologically scored inflammatory reactions to SELP are decreased in both the renal and hepatic implantations compared to Embosphere. In conclusion, a bioresorbable SELP liquid embolic system deeply penetrates target tissue and selectively embolizes blood vessels in vivo.

Single institution early clinical experience with the Scepter Mini balloon catheter

BACKGROUND

The use of liquid embolic agents in the endovascular treatment of dural arteriovenous (dAVFs) fistulas and brain arteriovenous malformations (AVMs) has become common practice. The use of dual lumen balloon microcatheters has greatly improved the efficacy of liquid embolization. The purpose of this series is to discuss our early experience with the Scepter Mini dual lumen balloon microcatheter.

METHODS

A retrospective chart review was performed of all patients who underwent embolization with the Scepter Mini dual lumen balloon at a single institution. Technical details and procedural complications were recorded for each case.

RESULTS

In total, 10 Scepter Mini dual lumen balloon microcatheters were used in nine patients. All patients except two were treated for AVMs. Technical success was achieved in all but one case where one balloon had to be discarded due to precipitation of the tantalum powder. Average vessel diameter where the balloon was inflated was 1.1 mm (0.8-2.4 mm). It provided flow arrest in 100% of cases with no cases of reflux of embolic material. Balloon "jump back" was found to occur in 44.4% (4/9) of cases. Seven out of nine cases used Onyx, and two cases used n-butyl cyanoacrylate.

CONCLUSIONS

The Scepter Mini is a new dual lumen balloon ideal for distal access and can be used for embolization with liquid embolic agents with a high degree of technical success. Its great benefit is the immediate and safe flow arrest of distal vasculature upon balloon inflation. One important consideration for effective embolization is early identification of balloon jump back.

Absence of skin discoloration after transarterial embolization of a subcutaneous auricular arteriovenous malformation with PHIL

BACKGROUND AND OBJECTIVE

One of the treatment options for arteriovenous malformations consists of embolization, with a choice of various embolic agents, with or without subsequent surgical excision. If embolization is offered without subsequent surgery, the embolic material will stay in situ, in which case the consistency and color become important in superficial lesions. The purpose of this case report is to describe if the use of a novel liquid embolic agent (PHIL) is well suited for treatment of superficial AVMs without subsequent surgery.

CASE DESCRIPTION

A 30-year-old male presented with a painful reddish, pulsatile swelling of the left ear that had been present for more than 10 years. Angiography confirmed an arteriovenous malformation supplied by the superficial temporal artery and the posterior auricular artery. The lesion was successfully treated by embolization with PHIL, through the superficial temporal artery. A minute residual shunt, from the posterior auricular artery, was accepted. Immediate disappearance of pulsatile tinnitus was reported. Moreover, return of normal skin color was observed without discomfort from the embolic deposits. This result has been stable throughout one year of clinical follow-up.

CONCLUSION

To our knowledge, this is the first case report describing PHIL embolization as a treatment option for superficial arteriovenous malformations without the necessity for subsequent surgery. The white color and rubbery consistency are beneficial characteristics of PHIL in treatment of subcutaneous lesions, especially in cosmetically relevant locations.

Onyx-HD 500 Embolization of a Traumatic Internal Carotid Artery Pseudoaneurysm after Transsphenoidal Surgery

BACKGROUND AND PURPOSE

Traumatic intracranial pseudoaneurysms present a challenge for treatment. Traditionally these lesions have required a deconstructive approach consisting of vessel sacrifice since their fragile nature often makes direct microsurgical repair or coil embolization hazardous. As a high-viscosity liquid embolic agent that results in immediate, vessel sparing aneurysm occlusion, Onyx-HD 500 represents a uniquely efficacious tool for this clinical situation.

CASE SUMMARY

We report the case of a 56-year-old right-handed gentleman who suffered a vascular injury to the ICA during revision transsphenoidal surgery for a recurrent pituitary macroadenoma. The patient was initially treated with nasal packing, but after recurrent episodes of epistaxis and a CT angiogram demonstrating a large traumatic ICA pseudoaneurysm, the patient was referred for invasive treatment. Given the presumed fragility of the lesion, embolization with Onyx-HD 500 was chosen in order to safely achieve immediate aneurysm occlusion without the need for vessel sacrifice. After an early recurrence due to incomplete initial embolization, the patient went on to complete occlusion without further hemorrhage.

CONCLUSION

This case illustrates the utility of a high-viscosity liquid embolic agent in providing immediate protection from rehemorrhage by occluding a large ruptured pseudoaneurysm of the proximal intracranial ICA, while sparing the parent artery.

Endovascular embolization of head and neck tumors

Endovascular tumor embolization as adjunctive therapy for head and neck cancers is evolving and has become an important part of the tools available for their treatment. Careful study of tumor vascular anatomy and adhering to general principles of intra-arterial therapy can prove this approach to be effective and safe. Various embolic materials are available and can be suited for a given tumor and its vascular supply. This article aims to summarize current methods and agents used in endovascular head and neck tumor embolization and discuss important angiographic and treatment characteristics of selected common head and neck tumors.