Surgical handling characteristics of an ethylene vinyl alcohol copolymer compared with N-butyl cyanoacrylate used for embolization of vessels in an arteriovenous malformation resection model in swine

Real-Time MRI Monitoring of Liquid Embolic Agent (Onyx) Injection in a Swine Arteriovenous Malformation Model

The paradigm is gradually shifting, with radiosurgery and endovascular embolization being increasingly chosen over surgical resection in the selected cases of brain arteriovenous malformations. Routinely used X-ray monitoring of liquid embolic infusion has very good spatial and temporal resolution but is not without significant drawbacks regarding poor visualization of the complex AVM angioarchitecture, especially after many embolizations in the past and therefore limiting the technical ability of the embocure-total occlusion of the feeding arteries, nidus, and draining veins. The purpose of this study was to evaluate the use of real-time MRI guidance in endovascular embolization with Onyx (instead of X-ray) in a single swine rete mirabile (RM) AVM model in order to provide the scaffolding for the real-time MRI guidance method. Onyx propagation was observed in real-time dynamic GE-EPI scan with initial ipsilateral RM filling followed by main cerebral arterial branch distribution. The relatively bright signal within RM and the brain prior to Onyx injection provided a good background for the dark, low signal of the embolic agent spreading in rete mirabile and brain arteries. X-ray picture confirmed Onyx cast distribution at the end of the procedure. In this initial experience, real-time MRI seems to be a promising method that may significantly improve liquid embolic agent infusion monitoring in the future, although requiring further development before clinical use.

Single institutional experience of peripheral applications of a liquid embolic agent: Ethylene Vinyl Alcohol Copolymer

OBJECTIVE

To evaluate the safety and efficacy of ethylene vinyl alcohol (EVOH) copolymer for the treatment of a variety of peripheral vascular pathologies.

RESULTS

Between October 2010 and October 2017, 43 patients who underwent total 54 EVOH embolization procedures for the treatment of peripheral vascular pathologies were included. The cases which involved the use of EVOH for the treatment of nonvascular, neurologic, ophthalmologic, otolaryngologic or head-neck pathologies were excluded. The demographic data, technical and clinical success rates, and procedure-related details and complications were obtained. The most common indications for EVOH embolization were type II endoleaks (n = 18) and peripheral arteriovenous malformations (n = 14). The majority of cases (62.5%) used EVOH without any adjunct embolic material. The results of this study showed 100% technical success rates and 89% clinical success rates. No events of nontarget embolization or other procedure-related complications were noted. The mortality & morbidity rates were 0%. The loss to follow up rate was 16% (9 /54). The mean follow-up period was 134 days (range, 30 to 522 days).

CONCLUSION

The single institutional experience supports the safety and efficacy of EVOH embolization in the treatment of various peripheral vascular conditions.

Percutaneous embolization using a combination of liquid embolic agents for the treatment of a large disfiguring venous malformation

A 25-year-old man with a venous malformation (VM) along the anterior and posterolateral aspects of the right chest wall presented with progressive enlargement of VM, chest wall pain, and physical disfigurement. Because of the complexity and size of the VM, a staged multidisciplinary team approach (ie, percutaneous embolization) followed by surgical resection and tissue-skin grafting was used. The percutaneous embolization was achieved with a combination of liquid embolic agents including n-butyl cyanoacrylate for the superficial cutaneous component and ethylene vinyl alcohol copolymer for the deeper subcutaneous component of the VM. Such a combination can achieve safe occlusion of the VM, facilitate surgical resection without blood loss, and contribute to a cosmetically desirable result.

Feasibility and Effectiveness of Direct Puncture and Onyx Embolization for Transverse Sinus Dural Arteriovenous Fistula

Direct puncture and embolization of the transverse sinus (TS) for treatment of dural arteriovenous fistula (DAVF) is typically performed with coils with or without glue. We report a case of DAVF at the left TS that was treated with Onyx embolization via direct puncture of the TS. A 75-year-old woman presented with tremor, festinating gait, and dysarthria. A left TS-DAVF with retrograde superior sagittal sinus and cortical venous reflux (Cognard type IIa+b) was identified on cerebral angiography, and both TSs were occluded with thrombi. We considered that achieving complete cure by transvenous embolization via the femoral vein or transarterial embolization via occipital feeders would be difficult. Thus, we performed a small craniotomy at the occipital bone to puncture the TS. The midportion of the TS was directly punctured with a 21-G microneedle under fluoroscopic guidance. We inserted a 5-F sheath into the TS. A microcatheter was then navigated into the affected sinus. Coils were placed through the microcatheter to support Onyx formation by reducing the pressure of shunting flow. Onyx embolization was performed with the same microcatheter. The DAVF was almost completely occluded except for the presence of minimal shunting flow to the proximal TS. After 1 week, time-of-flight magnetic resonance angiography showed complete resolution of DAVF. The patient showed resolved tremor and markedly improved mental status at 1-month follow up. Direct puncture and embolization of the TS using coils and Onyx is effective and feasible method for the treatment of DAVF when other approaches seem difficult.

What is the best therapeutic approach to a pediatric patient with a deep-seated brain AVM?

Although brain arteriovenous malformations (bAVMs) account for a very small proportion of cerebral pathologies in the pediatric population, they are the cause of roughly 50% of spontaneous intracranial hemorrhages. Pediatric bAVMs tend to rupture more frequently and seem to have higher recurrence rates than bAVMs in adults. Thus, the management of pediatric bAVMs is particularly challenging. In general, the treatment options are conservative treatment, microsurgery, endovascular therapy (EVT), gamma knife radiosurgery (GKRS), proton-beam stereotactic radiosurgery (PSRS), or a combination of the above. In order to identify the best approach to deep-seated pediatric bAVMs, we performed a systematic review, according to the PRISMA guidelines. None of the options seem to offer a clear advantage over the others when used alone. Microsurgery provides the highest obliteration rate, but has higher incidence of neurological complications. EVT may play a role when used as adjuvant therapy, but as a stand-alone therapy, the efficacy is low and the long-term side effects of radiation from the multiple sessions required in deep-seated pediatric bAVMs are still unknown. GKRS has a low risk of complication, but the obliteration rates still leave much to be desired. Finally, PSRS offers promising results with a more accurate radiation that avoids the surrounding tissue, but data is limited due to its recent introduction. Overall, a multi-modal approach, or even an active surveillance, might be the most suitable when facing deep-seated bAVM, considering the difficulty of their management and the high risk of complications in the pediatric population.

Preliminary experience with precipitating hydrophobic injectable liquid in brain arteriovenous malformations

Advancement in microcatheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations (AVMs). Precipitating hydrophobic injectable liquid (PHIL) (Microvention) is a newly introduced dimethyl sulfoxide-based embolic agent for endovascular use. Herein, we present three patients who underwent endovascular treatment of brain AVMs with PHIL, followed by surgical resection. Endovascular features and same-day surgical handling of the new embolic agent PHIL are presented along with histopathologic changes in the acute stage in brain AVMs are presented, and its major differences from Onyx. In our series, PHIL had moderate inflammatory reaction in the acute stage without any associated angionecrosis that is different than Onyx which cause mild inflammatory reaction with angionecrosis. Smallest vessel containing PHIL was 2.9 μm compared to 5 μm with Onyx, which suggests better penetration.

Transarterial venous sinus occlusion of dural arteriovenous fistulas using ONYX

PURPOSE

The purpose of this article is to present a case series of transarterial venous sinus occlusion for dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses.

MATERIALS AND METHODS

From 2006 to 2012, 11 patients with DAVF of the transverse and sigmoid sinuses were treated with transarterial closure of the affected venous sinus using ethylene vinyl alcohol copolymer (ONYX). The consecutive retrospective cohort included six female and five male patients with an age range of 30-79. Patients presented with stroke, intracranial hemorrhage, seizure, headache, focal neurologic deficit or cognitive change. Lesions were categorized as Cognard II a + b (n = 5) or Cognard II b (n = 6). Four of this latter group consisted of isolated sinus segments. Selection criteria for dural sinus occlusion included direct multi-hole fistulas involving a broad surface in length or circumference of the sinus wall. External carotid artery (ECA) branches were directly embolized when considered safe. High-risk arterial supply from ICA, PICA, AICA or ECA cranial nerve branches were closed via retrograde approach during sinus occlusion.

RESULTS

DAVF closure was accomplished in all 11 patients with a total of 17 embolization procedures using ONYX. High-risk arterial collaterals were closed via artery-artery or artery-sinus-artery embolization. The vein of Labbe was spared in the four cases with initial antegrade flow. No neurologic complications occurred, and DAVF closures were durable on three-month angiography.

CONCLUSION

Transarterial closure of the transverse and sigmoid sinuses.

Animal Models in Studying Cerebral Arteriovenous Malformation

Brain arteriovenous malformation (AVM) is an important cause of hemorrhagic stroke. The etiology is largely unknown and the therapeutics are controversial. A review of AVM-associated animal models may be helpful in order to understand the up-to-date knowledge and promote further research about the disease. We searched PubMed till December 31, 2014, with the term “arteriovenous malformation,” limiting results to animals and English language. Publications that described creations of AVM animal models or investigated AVM-related mechanisms and treatments using these models were reviewed. More than 100 articles fulfilling our inclusion criteria were identified, and from them eight different types of the original models were summarized. The backgrounds and procedures of these models, their applications, and research findings were demonstrated. Animal models are useful in studying the pathogenesis of AVM formation, growth, and rupture, as well as in developing and testing new treatments. Creations of preferable models are expected.

Focused post mortem dissection technique for harvest of rete mirabile in domestic swine (Sus scrofa)

BACKGROUND

Rete mirabile (RM) of the domestic pig is a popular animal model of arteriovenous malformations. The RM (Latin for 'wonderful net)' comprises the arterioarterial portal connecting ascending pharyngeal arteries and the internal carotid arteries, which exists in the skull base of even-toed ungulates. Although angiographic access of the RM is relatively easy, its post mortem procurement is complicated and its detailed technique has not been well described.

OBJECTIVE

To present our focused post mortem dissection technique for undamaged and complete harvest of the RM.

MATERIALS AND METHODS

Fourteen domestic (40-70 lb (18-32 kg)) swine were used in this study. Angiographies were performed under general anesthesia in all animals. A 5F Berenstein catheter was used for angiography and a 014 microcatheter was used to obtain superselective angiography. A stepwise surgical dissection technique has been developed to efficiently harvest RM. Angiographic and surgical anatomy were also compared.

RESULTS

The RM was supplied by bilateral ascending pharyngeal arteries. Bilateral anterior cerebral arteries, middle cerebral arteries, and the basilar system were identified rostral to the RM. Our surgical dissection technique was developed during a project to streamline harvesting of the RM and a stepwise description is as follows: (1) decapitate the swine by removing the head through the plane of the occiput and C1 vertebral body; (2) remove the tongue and oropharynx via a ventral approach; (3) dissect through the posterior pharyngeal wall identifying bilateral tympanic bullae and the basisphenoid bone; and (4) remove the basisphenoid bone about one and half inches above the rostral end of the tympanic bullae to fully expose the rete.

CONCLUSIONS

The RM can be procured efficiently and effectively with our technique, without requiring any sophisticated surgical devices.

Microcatheter entrapment retrieval from Onyx embolization in brain arteriovenous malformations: A technical note

OBJECTIVE

Many techniques have been use for retrieval of an entrapped microcatheter during Onyx (eV3 Neurovascular) embolization of brain arteriovenous malformations (BAVMs). We report our technique that we term "pull-push-pull" that can be utilized as first management in retrieving the microcatheter.

METHOD

We analyzed a total of 37 patients that underwent BAVM embolization with either Onyx 18 or 34 at our institution. Standard embolization techniques were utilized with the use of Marathon (eV3 Neurovascular) microcatheter. When difficulty in retrieving the microcatheter arose, we used the "pull-push-pull" technique. The technique comprises the eV3 protocol of retraction. In addition, the microcatheter is stretched causing the Onyx cast to stretch in its inner core, creating a more thorough cohesive property amongst the Onyx mixture. Then the microcatheter is pushed back and to its point of embolization origin. Afterwards, retraction of the microcatheter is enabled as it can be easily dislodged from the cast. Multiple attempts can be repeated as needed.

RESULT AND DISCUSSION

We had three patients that had difficulty with removal of microcatheter (8.1%). Utilization of the "pull-push-pull" technique was used on two of those patients. No neurological complication was observed with our technique. We believe the cohesive property of Onyx solution helps in the retrieval of the catheter by our method and technique.

CONCLUSION

We believe the "pull-push-pull" can be utilized and be an additional technique before attempting other catheter retrieval techniques in Onyx BAVM embolization.

Proliferative ischemic retinopathy after arteriovenous malformation embolization in a child with hereditary hemorrhagic telangiectasia

PURPOSE

To describe a case of hereditary hemorrhagic telangiectasia, presenting with multiple branch retinal artery occlusions, retinal ischemia, neovascularization, and vitreous hemorrhage after cerebral arteriovenous malformation embolization.

METHODS

The authors report a 7-year-old patient with decreased vision in his left eye after embolization of a pineal arteriovenous malformation secondary to hereditary hemorrhagic telangiectasia. Ophthalmic evaluation, fundus photography, fluorescein angiography, spectral domain optical coherence tomography, electroretinogram, examination under anesthesia, and pars plana vitrectomy (PPV) were performed.

RESULTS

Fundus examination of the left eye revealed extensive posterior segment ischemia, vascular tortuosity, and vitreous hemorrhage. Fluorescein angiography was remarkable for partial obstruction of retinal arteries, midperipheral nonperfusion, and associated leakage from multiple areas of neovascularization. Spectral domain optical coherence tomography was normal. Electroretinogram demonstrated decreased b-wave amplitude. The patient was subsequently treated with 25-gauge pars plana vitrectomy, panretinal endophotocoagulation, and intravitreal bevacizumab. Five weeks after surgery, best-corrected visual acuity had improved to 20/40, and examination showed resolution of vitreous hemorrhage and neovascularization.

CONCLUSION

Retinal vascular abnormalities, posterior segment ischemia, and vitreous hemorrhage suggested a combination of retinal involvement of hereditary hemorrhagic telangiectasia complicated by nontarget embolization.

Guidelines for the use of NBCA in vascular embolization devised by the Committee of Practice Guidelines of the Japanese Society of Interventional Radiology (CGJSIR), 2012 edition

Cyanoacrylates are a group of fast-acting adhesives. They form low viscosity liquids in the monomer state and instantly polymerize to become adhesive upon contact with ionic substances. Since the 1950s, they have been used around the world for industrial and household purposes. N-butyl cyanoacrylate (NBCA) is a cyanoacrylate that is commonly used for medical care, and the closure of skin wounds with NBCA has been found to promote hemostasis. However, in Japan, the intravascular injection of NBCA is considered to be off-label use, except during the treatment of gastric varices under endoscopy. The use of NBCA in embolotherapy is considered when the target vessels cannot be cannulated superselectively, for vascular diseases that require long segments of the target vessel to be embolized, or for patients in a hypocoagulable state. NBCA-based embolotherapy can be used to treat vascular malformations, acute hemorrhaging, tumors, and venous disease. The complications associated with NBCA-based embolotherapy include tissue ischemia, hemorrhaging, systemic or local reactions, and catheter adhesion to blood vessels. NBCA is mixed with Lipiodol to make it radiopaque and to adjust its polymerization time. Since there are various technical aspects to performing NBCA-based embolotherapy safely, it should be carried out by, or with the assistance of, proficient interventional radiologists.

Direct continuous measurement of draining vein pressure during Onyx embolization in a swine arteriovenous malformation model

OBJECTIVE

Periprocedural intracranial hemorrhage secondary to intranidal flow redirection may develop after arteriovenous malformation (AVM) embolization. We hypothesized that continuous draining vein pressure monitoring may identify clinically relevant hemodynamic changes during devascularization. Our goal was to characterize the draining vein pressures in a swine rete mirabile AVM model during embolization with Onyx.

METHODS

An acute swine AVM model was constructed in six animals. Baseline, transoperative and final AVM area measurements were used to determine the degree of AVM embolization. Continuous video recordings were captured at 10 s intervals of active embolization. Draining vein pressure, arterial feeder pressure and heart rate were continuously monitored.

RESULTS

The baseline and post-embolization mean draining vein pressures were 49.8±17.2 and 33.0±11.7 mm Hg (p=0.01), mean arterial pressures were 79.8±19.4 and 79.6±25.2 mm Hg (p=0.94), mean transnidal pressures were 35.8±19.7 and 45.4±33.7 mm Hg (p=0.37) and mean heart rates were 81.1±11.9 and 83.1±12.8 bpm (p=0.38), respectively. The draining vein pressure was averaged according to the degree of AVM embolization and represented as a relative change compared with the baseline draining vein pressure, and the slopes were found to decrease in all cases (p=0.02). In half of the animals the draining vein pressure decreased progressively as the AVM was embolized. In the remaining animals the venous pressure only started to decline after the AVM had been devascularized by > 50%.

CONCLUSIONS

The draining vein pressure response during Onyx embolization in the swine AVM model is heterogeneous. Continuous draining vein pressure monitoring is feasible and may potentially identify clinically relevant hemodynamic changes during AVM embolization.

Onyx®: a unique neuroembolic agent

Rupture of a cerebral arteriovenous malformation can result in devastating hemorrhage with a possibility of serious neurological injury or death. Endovascular embolization is an important adjunct in the treatment of cerebral arteriovenous malformations, and in a small number of cases may provide definitive treatment. Currently available embolic agents have several shortcomings, including the possibility of recanalization, adhesiveness to the endovascular microcatheter and suboptimal handling at the time of surgical resection. Onyx is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that was approved by the US FDA in July 2005 as an embolic agent for brain arteriovenous malformations. Although long-term follow-up is limited, this agent appears to offer several advantages over the other available embolic agents for the endovascular management of arteriovenous malformations and other vascular lesions.

Onyx embolization of intracranial arteriovenous malformations in pediatric patients

OBJECT

The authors undertook this study to assess the safety and efficacy of Onyx embolization in the treatment of intracranial arteriovenous malformations (AVMs) in pediatric patients.

METHODS

All pediatric Onyx embolization of intracranial AVM cases performed consecutively at a single children's hospital over a 5-year period were collected and evaluated.

RESULTS

Twenty-five patients (mean age 10.5 years) underwent a total of 38 procedures. An aggregate of 56 pedicles were embolized (mean 1.47 per session). The Spetzler-Martin grade was determined in all cases. Onyx embolization resulted in complete obliteration of the AVM in 3 cases (12%) and partial obliteration in 22 cases (88%). A total of 23 patients underwent surgical treatment. The mean preoperative AVM devascularization in these cases was 72%. One patient was treated with radiosurgery following Onyx embolization. Overall, 10 complications occurred in a total of 38 procedures (26.3%). None of the complications resulted in permanent neurological morbidity. The rate of transient neurological complications was 10.5% (4 of 38 procedures) and the rate of transient nonneurological complications was 5.3% (2 of 38 procedures). The remaining 4 complications were clinically silent (rate of 10.5%). There were no procedure-related deaths in this study population. There was no significant difference in patients with and without complications in terms of demographic characteristics, AVM grade, or embolization features (p ≥ 0.2). Deep venous drainage was associated with higher complication rates (p = 0.03).

CONCLUSIONS

Onyx utilization is feasible for preoperative or primary embolization in the treatment of pediatric intracranial AVMs; however, the spectrum of complications encountered is broad, and attention must be paid to the technical nuances of and indications for its use to avoid many potential dangerous effects. Although the overall complication rates were higher than expected, all were either clinically silent or had only transient clinical effects. Thus, this experience suggests that Onyx embolization can be performed safely with a low rate of permanent morbidity in pediatric patients harboring these difficult lesions.

ONYX versus n-BCA for embolization of cranial dural arteriovenous fistulas

PURPOSE

To evaluate the efficacy of n-butyl-2-cyanoacrylate (Trufill n-BCA) versus ethylene vinyl alcohol copolymer (ONYX) for the embolization of cranial dural arteriovenous fistulas (DAVF).

METHODS

Fifty-three consecutive patients with cranial dural AVF were treated with liquid embolic agents from November, 2003 to November, 2008. These 53 patients had 56 lesions treated with arterial embolization. Patients embolized to completion underwent follow-up angiography at 3 months to assess for durable occlusion.

RESULTS

Twenty-one lesions were treated with n-BCA. Seven patients treated with n-BCA had initial angiographic occlusion of their DAVF, which were durable at 3 months. Six patients had adjunctive treatment with coils and/or polyvinyl alcohol particles, but none of these were occluded by endovascular treatment alone. Eleven patients underwent post-embolization surgery for closure of their DAVF. There was one death related to intractable status epilepticus at presentation. One patient developed a major stroke from venous sinus thrombosis after embolization. Thirty-five lesions were treated with ONYX in 34 patients. Twenty-nine patients treated with ONYX had initial angiographic occlusion of their DAVF by embolization alone. One patient had recurrence at 3 months and was re-treated out of 27 total follow-ups. Four patients underwent post-embolization surgical obliteration of their lesions. No deaths or major strokes occurred in this cohort.

CONCLUSION

Initial angiographic occlusion (p=0.0004) and durable angiographic occlusion (p=0.0018) rates for embolization of cranial DAVF show a statistically significant higher efficacy with ONYX compared with n-BCA. Patients embolized with ONYX underwent surgery less frequently compared with those treated with n-BCA (p=0.0015).

The use of Onyx for embolization of peripheral vascular malformations in pediatric patients

PURPOSE

The management of congenital peripheral vascular malformations (VMs) can present a difficult therapeutic challenge. Endovascular transcatheter embolization of peripheral VMs is widely accepted as a first therapeutic option for many VMs. However, data describing the use of Onyx are limited in children with peripheral VMs. Our aim is to retrospectively evaluate the results of transcatheter arterial embolization with Onyx for peripheral VMs in children.

MATERIALS AND METHODS

We analyzed clinical and imaging records of 16 patients who underwent 25 embolization procedures by using Onyx for peripheral VMs. In eight cases, embolization procedures were performed once; in seven cases, twice; and in one case, thrice.

RESULTS

Embolization was technically complete in 4 patients and incomplete in 12 patients. Clinically, complete success was achieved in nine patients, and partial success was achieved in six patients. In one patient, reflux to the anterior and posterior tibial arteries caused peripheral ischemia, and the patient was referred to undergo plastic surgery. There were no complications in the other 15 patients.

CONCLUSION

With future studies to better characterize the safety profile of this agent in peripheral vasculature, embolization with Onyx may become a valuable treatment option for peripheral VMs in pediatric patients.

Spinal arteriovenous malformation presenting as spastic monoplegic cerebral palsy in a child

A case of spinal arterio-venous malformation (AVM) initially diagnosed as unilateral cerebral palsy (CP) is reported. The presentation was of a long-standing spastic monoparesis of the left leg, with initial response to Botulinum toxin injections to the calf and tibialis posterior muscles. This was followed by progressive deterioration occurring over a 3-month period before further investigation and definitive diagnosis at 7 years. Imaging demonstrated a large extra-medullary spinal AVM compressing the mid-thoracic cord. This was successfully managed by embolisation with a non-adhesive polymer: ethylene-vinyl alcohol copolymer injected into the dominant feeding vessel. This case highlights the need to consider alternative diagnoses when a child with a diagnosis of CP presents with atypical clinical features such as monoparesis and has worsening or altered clinical signs. Moreover, a normal magnetic resonance imaging brain scan and the absence of ipsilateral upper limb neurological signs or functional impairment should raise suspicion even in the context of static lower limb signs. A literature review was performed on the management of spinal AVM in children and this will be is discussed.

Direct endoscopic intratumoral injection of Onyx for the preoperative embolization of a recurrent juvenile nasal angiofibroma

Percutaneous injection of embolization material within head and neck tumors is being described as an alternative or adjunct to transarterial embolization. Access in these reports is by computed tomography (CT) guidance, which is cumbersome given the need to transport the patient from the CT scanner to angiography suite. We describe a case of direct percutaneous onyx embolization of juvenile nasal angiofibroma following endoscopic access in the angiography suite including self-sustained onyx combustion during surgical electrocautery.

A prospective, multicenter, randomized trial of the Onyx liquid embolic system and N-butyl cyanoacrylate embolization of cerebral arteriovenous malformations

Object

The Onyx liquid embolic system (Onyx) was approved in the European Union in 1999 for embolization of lesions in the intracranial and peripheral vasculature, including brain arteriovenous malformations (AVMs) and hypervascular tumors. In 2001 a prospective, equivalence, multicenter, randomized controlled trial was initiated to support a submission for FDA approval. The objective of this study was to verify the safety and efficacy of Onyx compared with N-butyl cyanoacrylate (NBCA) for the presurgical treatment of brain AVMs.

Methods

One hundred seventeen patients with brain AVMs were treated with either Onyx (54 patients) or NBCA (63 patients) for presurgical endovascular embolization between May 2001 and April 2003. The primary end point was technical success in achieving ≥ 50% reduction in AVM volume. Secondary end points were operative blood loss and resection time. All adverse events (AEs) were reported and assigned a relationship to the Onyx or NBCA system, treatment, disease, surgery, or other/unknown. The Data Safety Monitoring Board adjudicated AEs, and a blinded, independent core lab assessed volume measurements. Patients were monitored through discharge after the final surgery or through a 3- and/or 12-month follow-up if resection had not been performed or was incomplete.

Results

The use of Onyx led to ≥ 50% AVM volume reduction in 96% of cases versus 85% for NBCA (p = not significant). The secondary end points of resection time and blood loss were similar. Serious AEs were also similar between the 2 treatment groups.

Conclusions

Onyx is equivalent to NBCA in safety and efficacy as a preoperative embolic agent in reducing brain AVM volume by at least 50%.

Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

OBJECTIVES

To evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl alcohol copolymer from two centres.

METHODS

We retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone. Cause of haemorrhage and technical and clinical success were documented.

RESULTS

Arterial embolotherapy was successful in all 16 cases. The technical success rate was 100%. The cause of bleeding was pancreatitis in four, graft-versus-host disease (GVHD) of the colon in three, malignancy in three, angiodysplasia in two, ulcer in two and panarteritis nodosa and trauma in one each. There were no procedure-related complications. No bowel necrosis occurred because of embolisation. In 13 cases, the patients were discharged in good condition (81%); the three patients with GVHD died because of the underlying disease.

CONCLUSIONS

The copolymer seems to have great potential in embolotherapy of acute arterial gastrointestinal bleeding. In our series none of the patients had rebleeding at the site of embolisation and no clinically obvious bowel necrosis occurred.

Embolization of cranial dural arteriovenous fistulae with ONYX: Indications, techniques, and outcomes

OBJECTIVES

The purpose of this study was to establish the role of the liquid embolic agent, ONYX, in the treatment of cranial dural arteriovenous fistulae (DAVFs) and to redefine the indications, techniques and outcomes of treatment with ONYX.

MATERIALS AND METHODS

This is a retrospective study of 25 DAVF patients who underwent endovascular treatment with ONYX between February 2006 and July 2008. All patients of DAVF presenting in this period were treated with ONYX.

RESULTS

Anatomic cure (i.e., complete angiographic closure of the fistula) was achieved in a single session and through a single arterial pedicle injection in 21 out of 25 patients (cure rate of 84%). Out of four patients with residual fistulae, one achieved cure that was evident on a control angiogram obtained at 3 months while three had no vascular access for further embolization and so were referred for radiosurgery. There was only one recurrence seen in angiograms obtained at the end of one year and this patient was re-embolized successfully with ONYX. Complications were seen in two patients.

CONCLUSION

ONYX embolization of DAVFs has revolutionized the endovascular treatment of DAVFs, achieving high cure rates in a single session with minimal complications. Transarterial ONYX embolization should be the first option for all locations, except cavernous DAVFs.

Endovascular Treatment of Intracranial Dural Arteriovenous Fistulae Using Onyx: a Case Series

Objective:

An endovascular approach is often the first-line treatment of dural arteriovenous fistulae (DAVFs). Information on the use of Onyx (ev3 Neurovascular, Irvine, CA) for treating DAVFs, however, is limited. Therefore, we present our early experience, technical considerations, and complications associated with the use of Onyx for DAVF embolization.

Methods:

Twenty-eight patients with 29 DAVFs treated with Onyx embolization were included in this analysis. Hospital records, operative reports, and angiograms were reviewed and analyzed.

Results:

Forty Onyx procedures, including 39 transarterial and 1 transvenous approaches, were performed. Fifty-one external carotid artery branches, 8 posterior meningeal artery branches, and 3 internal carotid artery branches were used for Onyx embolization. Branches of the middle meningeal artery were embolized 32 times, and the occipital artery was embolized 15 times. Twenty-one fistulae (72%) were cured angiographically with endovascular therapy. Transarterial embolization via the middle meningeal artery cured 12 DAVFs (41%). Four complications (9.7%) were recorded, including 3 transient (7.3%) and 1 permanent neurological deficits (2.4%). Follow-up imaging, which was available for 8 fistulae with angiographic cures, showed no evidence of recurrence.

Conclusion:

Transarterial Onyx embolization of external carotid artery branches, particularly the middle meningeal artery, offers a high likelihood of cure. This technique provides a safe and effective method of embolization with few side effects and complications. However, long-term follow-up is needed to establish its efficacy.

Supratentorial Brain AVM Embolization with Onyx-18 and Post-Embolization Management. A Single-Center Experience

SUMMARY

Onyx is increasingly used in endovascular therapy of intracranial arteriovenous malformations (AVMs). However, the embolic effect and post-embolization management are still under discussion. We report our experience in the treatment of supratentorial brain arteriovenous malformations (SBAVMs) with Onyx and discuss post-embolic management. From June 2006 to July 2008, 20 patients with SBAVM were embolized with Onyx. There were 14 men and six women ranging from 14 to 64 years of age (mean 38.3 years). Initial symptoms included spontaneous hemorrhage (n=12), headaches (n=4), seizure (n=3) and incidentally disclosed after head trauma (n=1). After the endovascular procedure, all had subsequent treatment (follow-up angiogram, stereotactic radiosurgery or microsurgery) according to the obliteration degree. At angiography, seven patients (35%, 7/20) were completely obliterated (over 95% closure) after embolization while one suffered a small subarachnoid hemorrhage without permanent clinical sequelae. Four patients (20%, 4/20) were subtotally obliterated (over 80% closure), one patient who suffered severe cerebral edema after embolization underwent decompressive craniectomy, two patients had additional radiosurgery and one patient had follow-up angiogram. Nine patients (45%, 9/20) were partially obliterated (20-80% closure), five patients had additional surgery, two patients had additional radiosurgery and two patients had follow-up angiogram (one patient had intraventricular hemorrhage three months after embolization). Of all 20 AVMs, an average of 2.2 ml Onyx was used per patient and average volume reduction was 80% (range, 30%-99%). Onyx is suitable for embolization of SBAVMs because of its diffuse controllable properties. We suggest clinical follow-up after complete obliteration, additional radiosurgery or angiographic follow-up after subtotal obliteration and additional surgery after partially obliteration. More cases with long-term follow-up are needed to evaluate the long-term prognosis of our post-embolization management.

Evaluation of the toxicity of onyx compared with n-butyl 2-cyanoacrylate in the subarachnoid space of a rabbit model: an experimental research

INTRODUCTION

The toxic effects of onyx, its solvent dimethyl sulphoxide (DMSO), and n-butyl 2-cyanoacrylate (NBCA) were evaluated after infusion into the subaracnoid space of a rabbit model.

METHODS

Each of the two various concentrations of onyx, pure DMSO, NBCA, and normal saline solution were percutaneously infused into the pontocerebellar cisternae of 39 domestic male albino rabbits, after which, the brain stems and medial cerebellar tissues were harvested for biochemical and histopathological studies.

RESULTS

The specimens infused in various concentration of onyx, DMSO, and NBCA showed neural tissue necrosis and edema with inflammatory cell infitration in the acute stage. Although the mean values of the lipid peroxidase in the control, saline, and NBCA groups were found to be almost similar, they were found to be low in the onyx and DMSO groups.

CONCLUSION

This experimental study suggests that NBCA, and various concentrations of onyx and DMSO have toxic effects on the neural tissues of rabbits when infused into the subarachnoid space.

ONYX EMBOLIZATION FOR THE TREATMENT OF SPINAL DURAL ARTERIOVENOUS FISTULAE

OBJECTIVE

Spinal dural arteriovenous fistulae (SDAVF) are the most common variety of spinal vascular malformations. The Onyx liquid embolic system (ev3 Neurovascular, Irvine, CA) was recently approved for the treatment of intracranial arteriovenous malformations, but its use to treat SDAVFs is not yet well established. We report our initial experience with Onyx embolization in the treatment of SDAVFs.

METHODS

Retrospective analysis of 3 consecutive patients with SDAVFs who were treated with the Onyx as the single treatment modality was performed. Demographic, clinical, and radiographic presentations as well as long-term outcomes were reviewed.

RESULTS

Four procedures were performed in 3 patients. In all cases, transarterial microcatheterization was performed with a Marathon microcatheter (ev3 Neurovascular) and Onyx-18 (ev3 Neurovascular) was used. All 3 patients were men (age, 75–78 years) and presented with progressive myelopathy. Two patients underwent only 1 procedure, with a single pedicle embolized to achieve angiographic cure. In the remaining patient, 2 procedures with embolization through 3 different pedicles from 2 adjacent levels were necessary to achieve angiographic cure. No procedure-related complications were noted. No evidence of residual or recurrent SDAVF was seen on magnetic resonance imaging (mean, 10.6 months; range, 7.1–14.6 months), angiographic (mean, 12.2 months; range, 10.2–14.9 months), or clinical (mean, 13 months; range, 10.2–14.9 months) follow-up examination.

CONCLUSION

Our initial experience suggests that the endovascular treatment of SDAVFs with the Onyx is feasible, safe, and highly effective, as it allows for a controlled penetration of the embolic agent into the draining vein. In this small series, we found no evidence of clinical, magnetic resonance imaging, or angiographic recurrence during the long-term follow-up period.

The utility of onyx for preoperative embolization of cranial and spinal tumors

OBJECTIVE

To assess the utility, technical factors, and complications associated with the use of Onyx (Micro Therapeutics, Inc., Irvine, CA) for preoperative embolization of cranial and spinal tumors.

METHODS

We reviewed a prospectively accumulated database for patients in whom Onyx was used for preoperative embolization of cranial and spinal tumors over a 19-month period. The patients' demographic characteristics, tumor type and location, embolic agents used, arteries catheterized, and associated complications were assessed. Specific attention was focused on technical factors associated with the use of Onyx that differed from the use of other commonly used embolic materials.

RESULTS

Ten patients (four female and six male; age range, 11-60 yr) underwent preoperative embolization with Onyx before cranial or spinal tumor resection. Tumors included three juvenile nasal angiofibromas, two meningiomas, two hemangioblastomas, two metastases (renal cell and thyroid), and one giant cell tumor. Onyx embolization was performed in 43 vessels over 11 treatment sessions. There were no complications related to the embolization procedures. Deep penetration of the embolic agent into the tumor was documented through preoperative imaging or surgical pathological specimens.

CONCLUSION

Preoperative embolization of cranial and spinal tumors can be performed safely. Specific technical advantages of Onyx included deep penetration of lesions producing extensive tumor infarction, the ability to embolize extensive portions of the tumors through fewer arterial catheterizations, and the safety of catheter withdrawal despite often substantial reflux along the embolic catheter.

Treatment of arteriovenous malformations with hydrocoils in a Swine model

SUMMARY

Arteriovenous malformations (AVM) of the brain are the most common symptomatic congenital vascular malformation of the central nervous system, with significant associated morbidity and mortality. This study compared the feasibility and efficacy of treating AVMs by embolization with hydrocoils with similar treatment with bare platinum coils, using the swine rete mirabile as a model. A right carotid-jugular fistula was created in ten swine.A microcatheter was positioned into the rete mirabile, which was unilaterally (contralateral to the fistula) embolized with hydrocoils in six and bare platinum coils in four swine. Angiograms were evaluated during and immediately after embolization. Embolization with complete cessation of bloodf low in the unilateral rete mirabile was achieved in all animals treated with hydrocoils. The number of coils needed varied from four to seven (diameter 2-4 mm; mean coil length 22.3 cm). Embolization with platinum coils of similar number (seven) and slightly longer length (mean 37.75 cm) had a minimal effect on blood flow, resulting in occlusion of only small compartments. No immediate complications were noted with either coil. Hydrocoils are more effective in achieving embolization than bare platinum coils. Expansion of the hydrocoil over only a few minutes allows precise placement and stabilization of the coil before detachment. Hydrocoilscan be safely placed into small vessels. This approach may be particularly useful to decrease the flow rate, as a first stage of AVM embolizationin high flow AVMs that contain arteriovenous fistulae.

Angiographic exclusion of intracranial arteriovenous malformations using onyx®

Historically, endovascular treatment for cerebral arteriovenous malformations (AVMs) has been reserved as an adjunct to other modalities, namely radiosurgery and microsurgery, as the cure rate for cerebral AVMs treated solely with endovascular technique and older embolic agents is low. We report a series of five consecutive patients treated successfully with Onyx®, the newest available embolic agent, with resultant angiographic cure. Five patients aged three, nine, 33, 49, and 63 years were treated endovascularly for cerebral AVMs with a total of 19 embolizations with Onyx(®). All procedures were performed under general anesthesia with biplanar fluoroscopy. Complete angiographic obliteration of the AVM nidus was obtained in all cases with no residual filling. No immediate hemorrhagic or thromboembolic complications were observed. This early experience suggests that Onyx® has excellent embolization potential, and endovascular cure of AVMs may now be achieved with single modality therapy. Long terms data needs to be collected to further validate this observation.

Preliminary experience with onyx embolization for the treatment of intracranial dural arteriovenous fistulas

BACKGROUND AND PURPOSE

Onyx was recently approved for the treatment of pial arteriovenous malformations, but its use to treat dural arteriovenous fistulas (DAVFs) is not yet well established. We now report on the treatment of intracranial DAVFs using this nonadhesive liquid embolic agent.

MATERIALS AND METHODS

We performed a retrospective analysis of 12 consecutive patients with intracranial DAVFs who were treated with Onyx as the single treatment technique at our institution between March 2006 and February 2007.

RESULTS

A total of 17 procedures were performed in 12 patients. In all of the cases, transarterial microcatheterization was performed, and Onyx-18 or a combination of Onyx-18/Onyx-34 was used. Eight patients were men. The mean age was 56 +/- 12 years. Nine patients were symptomatic. There was an average of 5 feeders per DAVF (range, 1-9). Cortical venous reflux was present in all of the cases except for 1 of the symptomatic patients. Complete resolution of the DAVF on immediate posttreatment angiography was achieved in 10 patients. The remaining 2 patients had only minimal residual shunting postembolization, 1 of whom appeared cured on a follow-up angiogram 8 weeks later. The other patient has not yet had angiographic follow-up. Follow-up angiography (mean, 4.4 months) is currently available in 9 patients. There was 1 angiographic recurrence (asymptomatic), which was subsequently re-embolized with complete occlusion of the fistula and its draining vein. There was no significant morbidity or mortality.

CONCLUSION

In our experience, the endovascular treatment of intracranial DAVFs with Onyx is feasible, safe, and highly effective with a small recurrence rate in the short-term follow-up.

PREOPERATIVE EMBOLIZATION OF INTRACRANIAL ARTERIOVENOUS MALFORMATIONS WITH ONYX

OBJECTIVE

Preoperative embolization in accordance with multimodal therapies for cerebral arteriovenous malformations (AVMs) is generally the first step in treatment and may result in complete obliteration. The Onyx liquid embolic system (Micro Therapeutics, Inc., Irvine, CA) may offer advantages for intranidal targeted embolization and microsurgical resection. We present our experience in the combined treatment of intracranial AVMs using Onyx embolization and neurosurgical resection.

METHODS

We treated a total of 47 patients for compact intracranial AVMs that were located in the frontal or frontoparietal area (16 patients); temporal, temporoparietal, or temporo-occipital regions (12 patients); parietal or parieto-occipital areas (8 patients); occipital regions (8 patients); had basal ganglia involvement (2 patients); and was cerebellar (1 patient). The Spetzler-Martin grading scale values were as follows: 25 patients were Grades I or II, 10 patients were Grade III, and 12 patients were Grades IV or V. Twenty-three AVMs were located in eloquent brain regions.

RESULTS

After we performed final embolizations, the mean nidus reduction was 84%. Seven patients had new, nondisabling neurological deficits, and four patients had new, disabling neurological deficits after embolization. Periprocedurally, five vessel perforations and four stuck microcatheters were encountered without clinical deficits. In two patients, delayed hemorrhage after embolization occurred with good clinical outcome. We completely resected 46 AVMs; in one patient, we detected an AVM on postoperative angiography. The mean operative time was 4.7 hours, and the mean blood loss was 455 mL. Clinical status worsened postoperatively in 14 patients. Angiographic and clinical follow-up examinations were available for 42 patients (89%); the average follow-up period was 13 months. We found no relapse of arteriovenous shunt. Fourteen patients improved clinically after discharge. Of the 42 patients followed up, 23 individuals had no neurological deficit, 16 had a nondisabling deficit, and three had a disabling deficit.

CONCLUSION

Preoperative use of the Onyx liquid embolic system in cerebral AVM treatment allows profound occlusion by targeted embolization and provides a basis for safe neurosurgical resection.

Endovascular embolization of visceral artery aneurysms with ethylene-vinyl alcohol (Onyx): a case series

We report the application of the liquid embolic agent ethylene-vinyl alcohol (Onyx; MicroTherapeutics, Irvine, CA, USA) in the management of visceral artery aneurysms. The technique and indications for using Onyx are discussed with emphasis on the management of wide-necked aneurysms and maintenance of patency of the parent vessel. None of the cases was considered suitable for stent-grafting or embolization with conventional agents. Two aneurysms of the renal artery bifurcation and one aneurysm of the inferior pancreaticoduodenal artery were treated. Following treatment there was complete exclusion of all aneurysms. There was no evidence of end-organ infarction. Follow-up with intervals up to 6 months has shown sustained aneurysm exclusion. Onyx is known to be effective in the management of intracranial aneurysms. Our experience demonstrates the efficacy and applicability of the use of Onyx in the treatment of complex visceral artery aneurysms.

Therapy of brain arteriovenous malformations: multimodality treatment from a balanced standpoint

The three therapeutic modalities for arteriovenous malformation (AVM) treatment (surgery, embolization, and radiotherapy) developed in the past years with specific tools, each tool with its own qualities. Soon after the implementation of embolization for treatment of AVMs, this technique was used in combination with microsurgery; since the development of radiosurgery, treatment algorithms combining embolization with surgery and eventual subsequent radiosurgery, embolization with radiosurgery, or surgery with subsequent radiosurgery have been reported. These different combinations have been in use under the term multimodality treatment for many years, but the algorithms regarding the combination of tools, which tool has priority, and how the risk levels of each tool are assessed shows great variability among institutions. Centers with a surgical background see embolization as a technique to increase surgical feasibility and radiosurgery as a tool to complete subtotal AVM excision. Institutions with an endovascular background embolize AVMs with the aim of maximal occlusion rates and view surgery or radiosurgery as a technique to be used if the goal of total endovascular occlusion cannot be achieved. Radiosurgeons receive patients after incomplete embolization or surgical extirpation or a combination of both.

Controlling delivery properties of a waterborne,in-situ-forming biomaterial

This study details efforts to transition an in-situ-gelling polymer for endovascular embolization from the bench-top to preclinical cerebral arteriovenous malformation animal model studies. The in-situ-forming gel is based on waterborne, reverse emulsion materials. For controlled embolization of vascular defects, it is crucial to understand the delivery properties of an in-situ-forming gel. Directing a liquid into a small cavity requires both precise control of the fluid flow, and depends upon minimal variability in the materials behavior. A 2(3) factorial experiment performed in the laboratory revealed that temperature, mixing time, and buffer strength are all significant factors affecting the gelation time of the specific system studied. All three factors were also seen to reduce the standard deviation on the gel times. Changing the temperature from 21.3 to 37.0 degrees C reduced the cross population variability from 6.0 +/- 3.3 min to 3.4 +/- 1.6 min. At 30-s premixing, the protocol produced an average gel time of 5.3 +/- 3.0 min, which was reduced to 3.3 +/- 1.2 min with 90 s. Finally, a 50 mM buffer solution provided a gel time of 6.5 +/- 3.2 min, which was reduced to 2.95 +/- 0.6 min at 100 mM. Viscosity data was analyzed to suggest a model for injection volume and viscosity.

Surgical Endovascular Neuroradiology in the 21st Century: What Lies Ahead?

FEW COULD HAVE imagined the tremendous growth of endovascular surgery over the past 40 years. Endovascular therapy has greatly enhanced the care of the patient in neurosurgery, spine surgery, and head and neck surgery. Progress in technology and techniques continue to push forward the boundaries of what is deemed “treatable,” assuming acceptable risk. This article will briefly review the current state of endovascular surgery and speculate about what its role will be in the near and far future. Endovascular therapy provides a minimally invasive approach to the central nervous system and other systems via natural and, at times, highly selective pathways. Maximizing the accessibility of these routes to highly specific regions of the central nervous system provides an elegant and minimalist approach to treating diseases of the central nervous system with almost no “footprints” of ever having accessed the region. In the future, safe, efficient and intelligent delivery systems that may enhance or alter the tissue's response may result in successful treatment of cerebrovascular diseases, as well as other diseases of the craniospinal axis. The growth of nanotechnology, metallurgy, synthetic polymers, imaging, and training will all combine to help grow the technology and the science that is surgical endovascular neuroradiology.

Treatment of a superior sagittal sinus dural arteriovenous fistula with Onyx: technical case report

OBJECTIVE

The endovascular treatment of a complex superior sagittal sinus dural arteriovenous fistula with ethylene vinyl alcohol copolymer (Onyx) in one session is described.

CLINICAL PRESENTATION

A 54-year-old man presented with dizziness and a bruit. A cerebral angiogram demonstrated a superior sagittal sinus dural arteriovenous fistula with a patent superior sagittal sinus that was supplied via multiple branches of the external carotid arteries bilaterally and the left anterior and middle cerebral arteries. Drainage was mainly through the superior sagittal sinus and, only in part, retrogradely through the cortical veins. A decision was made to proceed with endovascular treatment followed by surgery.

INTERVENTION

Transarterial injection of one pedicle of middle meningeal artery on both sides with Onyx resulted in complete obliteration of the dural supply and some of the pial supply to the malformation without complications. The superior sagittal sinus remained patent. Based on this result, surgical treatment was cancelled. The residual pial supply had disappeared by the 10-month angiographic follow-up examination and the patient remained neurologically intact and without symptoms.

CONCLUSION

Definitive treatment may be attained with Onyx in dural arteriovenous fistulas. The potential of Onyx for use as a permanent embolic agent in dural arteriovenous fistulae needs to be investigated.

In vivo intraaneurysmal pressure measurements in experimental lateral wall aneurysms before and after onyx embolization

BACKGROUND

The aim of this study is to measure and compare the in vivo intraaneurysmal pressures of experimental lateral wall aneurysms, before and after onyx embolization. The data of this experiment will carry an important role in forming the scientific basis for the clinical endovascular applications.

MATERIALS AND METHODS

Five experimental lateral wall aneurysms were created by microsurgical techniques in 5 New Zealand rabbits' right common carotid arteries. Onyx embolization was applied to the aneurysms. Intraaneurysmal dome pressure and parent artery measurements before and after the procedure were recorded.

RESULTS

The mean arterial pressure recording in parent artery was 69.2 +/- 2.588 mm Hg under anesthesia. Mean heart rate was 131 beats per minute. The values were in physiologic limits. Meanwhile, aneurysm intradomal pressure recording showed a mean value of 59.2 +/- 5.069 mm Hg. Although there was incomplete occlusion of the aneurysm, intradomal mean pressure was recorded to be 24.4 +/- 8.876 mm Hg. After complete occlusion by onyx, mean intradomal aneurysm pressure was found to be 1.8 +/- 0.836 mm Hg.

DISCUSSION

This study is the first study reporting on intraaneurysmal pressure measurements before and after onyx embolization. The results in this experiment tend to show the adequate intraaneurysmal pressure control of onyx. This is important in the stabilization of the aneurysm to prevent rupture and rerupture. When compared with the findings of GDC coil, onyx embolization seems to be superior in intraaneurysmal pressure control.

CONCLUSION

In this study, it has been shown that onyx embolization decreases the intradomal aneurysmal pressure effectively.

Clinical Analysis of 50 Cases of BAVM Embolization with Onyx, a Novel Liquid Embolic Agent

SUMMARY

To report the embolization technique of using Onyx, a new liquid embolic agent, to treat cerebral arteriovenous malformations (AVMs) as well as its efficacy. 38 cases of cerebral AVMs located in eloquent area (motor, speech, visual nerve center), 9 in deep cerebral area, and another 3 cases in cerebellar hemisphere. The diameter of AVMs was smaller than 3cm in 10 cases, 3-6cm in 30 cases, and larger than 6cm in 10 cases.A 6F sheath was placed into the femoral artery after Selding's puncture. After a 6F guiding catheter was introduced into the internal carotid artery or vertebral artery, Ultraflow or Marathon microcatheter could be navigated into the nidus of AVMs.A long-slow injection of Onyx under fluoroscopic control was performed to embolize cerebral AVMs by adopting the "plug and push" technique. 10 AVM cases (20.0%) were considered to be totally occluded with Onyx in this group, 3 cases of which were found no regrowth by a 6-month follow-up. 25 cases (50%) were subtotally occluded while another 15 cases (30%) were partially embolized. Complications include: (1) severe cerebral hemorrhage occurred in three cases, two of them left hemiplegia after hematoma resection. (2) mild hemiplegia occurred in one lager frontal AVM patient. (3) mild visual deficit was left in one larger occipital AVM case. There was no severe complication in other 45 patients. Onyx has unique and distinctive superiority in treating cerebral AVMs. Nonetheless, the correct embolization technique should be learned to achieve good clinical results and to avoid complications. The long-term efficacy of Onyx embolization needs to be followed up.

Endovascular Treatment of Cerebral AVM: Our Experience with Onyx

SUMMARY

We have been using Onyx, a non-adhesive liquid polymer, to treat cerebral AVMs endovascularly since 1999. During this time we have treated 45 consecutive, unselected patients. From the outset this product brought about a change in our approach to treating this type of lesion because of the different injection behaviour observed for this material compared with the adhesive Histoacryl that had been employed until then. The object of this article is to assess the results achieved by our team using this new embolic agent, following angiographic and clinical follow- up of cases for a minimum of six months and a maximum of five years (mean: two years). We propose new categories of cerebral AVM based on the expected behaviour of Onyx within the nidus. Our appraisal indicates that we have improved our angiographic results, achieving complete occlusion of the malformation in 22% of cases and over 80-% closure in 69% of cases. The morbimortality rate for the procedure was 18%.

Transvenous Treatment of a Dural Arteriovenous Fistula of the Transverse Sinus by Embolization with Platinum Coils and Onyx HD 500+

SUMMARY

We report the endovascular treatment of a symptomatic dural arteriovenous fistula in a 61- year-old male patient. The medial portion of the fistula was occluded with detachable platinum coils during an initial intervention using a transvenous approach. Due to persistence of the symptoms in a second intervention eight months later the fistula was completely occluded by the transvenous introduction of a liquid embolic agent (Onyx 500+). The liquid embolic agent was introduced under protection by the temporary balloon occlusion of the fistula's venous drainage. After the procedure, the patient was treated for three months with 75 mg clopidogrel (Plavix(R)) and with 100 mg acetylsalicylic acid (ASS(R)). A few days after the intervention, the patient was discharged without any neurological deficit and in good clinical condition. The follow- up examination six months later neither detected a recurrence of the dural arteriovenous fistula in the angiogram nor any neurological symptoms.

Endovascular Treatment of Cerebral Arteriovenous Malformations

The modern management of cerebral arteriovenous malformations (AVMs) is based on three therapeutic modalities: microneurosurgery, endovascular embolization, and stereotactic radiosurgery. Embolization facilitates subsequent radiosurgery by reducing the volume of the nidus, prepares the resection of surgically accessible AVMs, and immediately addresses the risks related to associated intra/extranidal aneurysms and arteriovenous fistulas. We discuss in this article the current state of AVM endovascular therapy.