Severe pulmonary oedema following therapeutic embolization with Onyx for cerebral arteriovenous malformation

Comparison of Embolization Using Coil Versus Coil and Ethylene Vinyl Alcohol Copolymer in Pelvic venous Disorders

BACKGROUND

Endovascular treatments are frequently applied in pelvic venous disorders (PeVDs) with guidelines recommendations. There is no clear answer as to which of the embolization methods applied with endovascular treatments is superior. In this study, we aimed to compare the outcomes and symptom relief of patients with PeVDs treated using coils alone versus those treated with both coils and ethylene vinyl alcohol copolymer, as well as to evaluate the material usage and safety and efficacy of these treatments.

METHODS

Patients with PeVDs who underwent embolization of ovarian veins with coil and/or ethylene vinyl alcohol copolymer between January 2022 and April 2024 were included in the study. These patients were divided into 2 groups: patients who underwent coil embolization only (Group I) and patients who used ethylene vinyl alcohol copolymer together with coils (Group II). These patients were followed up at first, third 6th and 12th months postoperatively. Symptoms were evaluated with an examination and a visual analog scale (VAS).

RESULTS

Between January 2022 and April 2024, 90 patients with PeVDs who underwent endovascular treatment of their ovarian and pelvic veins were included in our study. 31 patients underwent coil embolization only (Group I), while 59 received both coil embolization and a ethylene vinyl alcohol copolymer (Group II). The mean age was 37.5 ± 7.9 and 40.4 ± 7.9 for Groups I and II, respectively. In group I, When pelvic pain was evaluated with VAS, there was a significant decrease in VAS scores between the preoperative period and at the first (VAS: 5.3 ± 0.9), third (VAS:3.9 ± 1.2), sixth (VAS: 3.5 ± 1.5), and 12th (VAS: 3.6 ± 1.5) months postoperatively (P = 0.011, <0.001, <0.001, <0.001, respectively). In Group II, When pelvic pain was evaluated with VAS, there was a similarly significant decrease in VAS scores between the preoperative period and the first (VAS: 5.3 ± 1.4), third (VAS: 3.3 ± 1.7), sixth (VAS: 2.8 ± 1.8), and 12th (VAS: 2.5 ± 2.1) months postoperatively (P = 0.002, <0.001, <0.001, <0.001, respectively). Group II demonstrated significantly lower VAS scores at the third, sixth, and 12th months compared to Group I. When examining the clinical symptoms of the patients individually, no significant differences were observed between the preoperative and first-month VAS scores for any specific symptom. However, at the third, sixth, and 12th months, while there were no significant differences between Group I and Group II in terms of menstrual pain, Group II exhibited significantly lower scores for standing abdominal pain, sitting abdominal pain, and dyspareunia.

CONLUSIONS

In our study, the use of ethylene vinyl alcohol copolymer and coils in the embolization of PeVDs is considered an effective and safe procedure with a higher clinical efficacy rate compared to other embolization techniques. Additionally, the use of ethylene vinyl alcohol copolymer reduces the need for coils, providing a cost-effective advantage.

Novel temperature responsive polymer based sealant for embolization

A sealant has been developed that improves upon current catheter-based treatments in the following ways: 1) Efficient delivery system, 2) No in situ polymerization, 3) No harmful byproducts, and 4) Cost-effective formulation. During the development process, particular attention was given to materials that were tunable, safe, and effective sealant agents. The thermo-responsive properties of poly(N-isopropylacrylamide) (PNIPAM) provides an ideal foundation to develop an optimized solution. Through a combination of model-based and material testing, a hydrogel was developed that balances conformational factors to achieve a customized transition temperature, radiopacity suitable for visualization, mechanical properties suitable for delivery via 3Fr catheter, sufficient cohesion once applied to resist migration under physiological pressures and an improved safety profile. Two applications, embolization of lymphatic leakage and exclusions of the left atrial appendage (LAA), to eliminate LAA dead space to reduce the risk of thromboembolic events, were considered. The material and benchtop results for this product demonstrate the suitability of this new material not only for these applications but also for other potential healthcare applications.

Efficacy and Safety of Ethylene-Vinyl Alcohol (EVOH) Copolymer-Based Non-Adhesive Liquid Embolic Agents (NALEAs) in Transcatheter Arterial Embolization (TAE) of Acute Non-Neurovascular Bleeding: A Multicenter Retrospective Cohort Study

Background and Objectives: Transcatheter arterial embolization (TAE) is part of the daily practice of most interventional radiologists worldwide. The ideal liquid embolic agent is far from being identified. Non-adhesive liquid embolic agents (NALEA) harden from the outside to the inside, resulting in deep penetration, known as "magma-like" progression, which permits a more distal embolization with good control of the embolic material. This multicenter retrospective cohort study aims to assess the efficacy, feasibility and safety of transcatheter arterial embolization (TAE) with ethylene-vinyl alcohol (EVOH)-based NALEAs (Onyx and Squid) in acute bleeding outside of the neurovascular area. Materials and Methods: This study is a multicenter analysis of retrospectively collected data of consecutive patients who had undergone, from January 2015 to December 2022, transcatheter arterial embolization with non-adhesive EVOH-based agents in the setting of acute non-neurovascular bleeding. Results: Fifty-three patients underwent transcatheter arterial embolization for acute non-neurovascular bleeding. Eight (15.1%) procedures were performed in patients with coagulopathy. The most used concentration of EVOH-based NALEAs was 34 (i.e., 8%), with a mean dose of 0.5 (±0.3) mL. The mean CT-to-groin time, the mean procedure time, the mean CT-to-embolization time and the mean fluoroscopy time were 22.9 (±12.4) min, 27.5 (±7) min, 50.3 (±13.1) min and 7.5 (±2.8) min, respectively. Technical success was achieved in all cases with a 96.2% clinical success rate. Complications were recorded in six (11.3%) patients. No statistically significant differences were observed between the group of patients with coagulopathy and the group of patients without coagulopathy in terms of efficacy and safety endpoints. Conclusions: Transcatheter arterial embolization (TAE) performed with non-adhesive EVOH-based embolic agents is an effective, feasible and safe strategy for the management of acute non-neurovascular bleeding, even in the subgroup of patients with coagulopathy.

Embolization in pelvic venous disorders using ethylene vinyl alcohol copolymer (Onyx®) and Aetoxysclerol: a prospective evaluation of safety and long-term efficacy

OBJECTIVES

To prospectively evaluate the safety and efficacy of embolization using ethylene vinyl alcohol copolymer (Onyx^®) and Aetoxysclerol for treatment of pelvic venous disorders (PeVD).

METHODS

This prospective study was approved by the institutional ethics review board. Ten clinical parameters were retained for evaluation of PeVD (pelvic pain, dyspareunia, post-coital pain, menstruation pain, lower limbs pain, difficulty walking, aesthetic discomfort, impact on daily working life, psychological impact and impact on daily life), measured on a visual analogue scale (VAS) between 0 and 10, and a global score out of 100 was noted before embolization, after 3 months during the imaging follow-up, and at the end of follow-up by phone call. The main criterion was clinical efficacy of embolization defined by an impairment score < 40/100 and a 50% decrease in overall score. Complications were recorded. Visualization of Onyx^® on MRI 3 months after embolization was noted.

RESULTS

Between July 2017 and May 2019, 73 consecutive women (mean age ± SD [range]: 41 ± 11 years [25-77]) treated by embolization with Onyx^® and Aetoxysclerol were included. The median follow-up was 28 months [Q1-Q3: 24.0-29.2] (range: 18.1-34.5). The median initial VAS impairment score was 39/100 [29.75-48.50] (12-58). Clinical efficacy was obtained for 70 patients (70/73, 95.9%), and the median VAS impairment score at the end of follow-up was significantly lower at 3 [0.00-7.25] (0-73) (p < 0.0001). Four minor complications occurred. Onyx^® was visualized on DIXON sequence of MRI for all patients.

CONCLUSION

Embolization using Onyx^® and Aetoxysclerol for PeVD is safe and effective.

KEY POINTS

• Embolization using Onyx^® and Aetoxysclerol for pelvic venous disorders is safe and effective. • Imaging follow-up is facilitated by visualization of Onyx^® on MRI DIXON sequences.

Endovascular embolization for cases of 'hidden' pediatric cerebral arteriovenous malformations: A diagnostic & therapeutic challenge

BACKGROUND

Ruptured arteriovenous malformations (AVM) hold a larger proportion as the cause of spontaneous intracranial hemorrhage in children compared to those in adults. Although surgical excision still remains as the gold standard therapy for arteriovenous malformations, some smaller ones are reported to resolve from embolization alone. However, difficulty arises when small arteriovenous malformations are not detected on certain diagnostic modalities such as Computed Tomography Angiography (CTA), giving rise to false negatives, which may compromise appropriate management of patients. Endovascular embolization can be used as alternative options as diagnostic and therapy for invisible arteriovenous malformation in children. We report two cases of ruptured paediatrics arteriovenous malformations with a complication of hydrocephalus, managed with endovascular embolization and a cerebrospinal fluid diversionary procedure.

CASE DESCRIPTION

We report 2 case in from Dr. Soetomo academic general hospital in 2021, the first case was a fully conscious 6-year-old-female child with sudden left-sided weakness and severe headache in January, and the second case a 9-year-old female came with decreased consciousness in May. Both had evidence of intracerebral hemorrhage, intraventricular hemorrhage, and hydrocephalus on head radiological examination, but no visible vascular malformations on Computed Tomography Angiography. The first patient was treated with extra ventricular drainage initially, while the second case was not. Transfemoral cerebral angiography revealed small arteriovenous malformations in both patients, and both had successful endovascular embolization afterwards. The first case was shunt-free, while the second case had her drainage switched to ventriculoperitoneal shunt right after the embolization procedure. Both patients recovered fully without complications and sequelae, and were discharged afterwards.

DISCUSSION

Both patients did not undergo surgical resection of the arteriovenous malformations; the first case only underwent endovascular embolization, while the second case underwent embolization and ventriculoperitoneal shunting. The cases described here help highlight the irreplaceable role of Transfemoral Cerebral Angiography as a gold standard for cases for arteriovenous malformations compared to other modalities, such as Computed Tomography Angiography (CTA). Smaller arteriovenous malformations in paediatrics are reported to achieve complete radiological resolution, and cerebrospinal fluid diversion in hydrocephalic cases are not always performed. Several factors to be considered include initial consciousness and severity of neurological deficit, which were taken into account in the management of our patients.

CONCLUSION

Embolization procedures may be beneficial in some pediatric arteriovenous malformations, preferably in smaller ones that undetectable by angiography. Several factors such as the consciousness and neurological deficit upon initial presentation may help in the decision making of these cases.

Portal vein embolization with ethylene-vinyl alcohol copolymer for contralateral lobe hypertrophy before liver resection: safety, feasibility and initial experience

Background

To report our preliminary experience with preoperative portal vein embolization (PVE) using liquid ethylene vinyl alcohol (EVOH) copolymer.

Methods

Retrospectively review of patients with primary or secondary liver malignancies scheduled for extensive hepatectomy after the induction of future liver remnant (FLR) hypertrophy by right or left PVE with EVOH as the only embolic agent between 2014 and 2018 at two academic centers. Cross-sectional imaging liver volumetry data obtained before and 3-6 weeks after PVE were used to assess the FLR volume (FLRV) increase, degree of FLR hypertrophy and the FLR kinetic growth rate (KGR).

Results

Twenty-six patients (17 males; mean age, 58.7±11 years; range, 32-79 years) were included. The technical and clinical success rate was 100%. PVE produced adequate FLR hypertrophy in all patients. Embolization occurred in all targeted portal branches and in no non-target vessels. The %FLRV increased by 52.9%±32.5% and the degree of FLR hypertrophy was 16.7%±6.8%. The KGR was 4.4%±2.0% per week. Four patients experience minor complications after PVE which resolved with symptomatic treatment. The resection rate was 84.5%. One patient died during surgery for reasons unrelated to PVE.

Conclusions

Preoperative PVE with EVOH copolymer is feasible, safe, and effective in inducing FLR hypertrophy.

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.

A Case Report of Onyx Pulmonary Arterial Embolism Contributing to Hypoxemia During Awake Craniotomy for Arteriovenous Malformation Resection

A healthy 26-year-old man with cerebral arteriovenous malformation underwent staged endovascular embolization with Onyx followed by awake craniotomy for resection. The perioperative course was complicated by tachycardia and severe intraoperative hypoxemia requiring significant oxygen supplementation. Postoperative chest computed tomography (CT) revealed hyperattenuating Onyx embolization material within the pulmonary vasculature, and an electrocardiogram indicated possible right heart strain, supporting clinically significant embolism. With awake arteriovenous malformation resection following adjunctive Onyx embolization becoming increasingly employed for lesions involving the eloquent cortex, anesthesiologists need to be aware of pulmonary migration of Onyx material as a potential contributor to significant perioperative hypoxemia.

Arteriovenous Malformations in the Pediatric Population: Review of the Existing Literature

Arteriovenous malformations (AVMs) in the pediatric population are relatively rare but reportedly carry a higher rate of rupture than in adults. This could be due to the fact that most pediatric AVMs are only detected after rupture. We aimed to review the current literature regarding the natural history and the clinical outcome after multimodality AVM treatment in the pediatric population, as optimal management for pediatric AVMs remains controversial. A multidisciplinary approach using multimodality therapy if needed has been proved to be beneficial in approaching these lesions in all age groups. Microsurgical resection remains the gold standard for the treatment of all accessible pediatric AVMs. Embolization and radiosurgery should be considered as an adjunctive therapy. Embolization provides a useful adjunct therapy to microsurgery by preventing significant blood loss and to radiosurgery by decreasing the volume of the AVM. Radiosurgery has been described to provide an alternative treatment approach in certain circumstances either as a primary or adjuvant therapy.

Ethylene vinyl alcohol copolymer (Onyx®) in peripheral interventional radiology: indications, advantages and limitations

Onyx(®) is a remarkable liquid embolizing agent that may allow a well-trained operator to undertake challenging embolization procedures. In multiple interventional radiology indications, the physico-chemical properties of Onyx(®) allow safe embolization. The purpose of this article is to review the advantages and disadvantages of Onyx(®) and identify its main indications.

Onyx HD-500 for embolization of cerebral aneurysms

In this article, the indications for, technical principles of, and complications/outcomes after Onyx cerebral aneurysm embolization are reviewed.

Preoperative tumor embolization

In this article, the authors review general principles and technical details of preoperative embolization of various hypervascular head, neck, and spinal tumors encountered in contemporary neuroendovascular practice. Indications, treatment goals, techniques, outcomes, and complications are discussed, and illustrative case examples are presented.

A Novel Method for Super-selective Coil Embolization Using an Extremely Soft Bare Coil through a Liquid Embolic Delivery Microcatheter

Endovascular coil embolization for intracranial aneurysms, arteriovenous malformations (AVMs), dural arteriovenous fistulas (AVFs), and hypervascular tumors are recognized as an effective adjunctive or curative treatment. In this setting, it is sometimes difficult to navigate a coil delivery microcatheter to the target point of a tiny, tortuous vessel. We herein present a case series of a novel method that enabled super-selective coil embolization using an extremely soft bare, electrodetachable coil (ED extrasoft^® coil) through a liquid embolic delivery microcatheter (Marathon^®). The Marathon^® catheter was successfully placed at the target point of the tiny, tortuous vessel, and coil embolization was achieved in all 16 patients with 9 AVMs, 2 distal aneurysms, 2 AVFs, and 3 meningiomas. The primary ED extrasoft^® coil and delivery wire have a very small radius, and the coil is rapidly detachable with an alarm notice from the generator even under Marathon^® with one marker. We believe that this technique can provide safe and efficient embolization for selected patients.

Fistula component of cerebral arteriovenous malformations: morphologic change after stereotactic radiosurgery and outcome of embolisation

BACKGROUND

The angioarchitecture of arteriovenous fistulas (AVFs) of cerebral arteriovenous malformation (CAVM) after stereotactic radiosurgery (SRS) remain unclear. The purpose of this study is to report the angiographic change of AVF components of CAVMs after SRS and outcomes of endovascular embolisation.

METHODS

From 2002 to 2012, a total of 523 CAVMs had been treated primarily by SRS with more than 3-year latency. Among these databases, there were 19 patients with 21 AVFs undergoing embolization after SRS. We retrospectively analyzed the angioarchitecture of the CAVM to identify AVFs, morphologic change and outcomes of AVFs after SRS and embolisation.

RESULTS

Eight AVFs were in the periphery of CAVMs, the other 13 were in a central location. Eighteen of 21 AVFs remained constant in morphology after SRS, while three feeders of AVFs were associated with radiation arteritis. The causes of failure to identify AVFs before SRS were overlooked (n = 7) or there was superimposition with feeders, nidus and/or venous drains of CAVMs (n = 14). Total fistula occlusion was achieved in all 21 AVFs; residual CAVMs was totally obliterated by embolisation and/or additional SRS in 12 patients. One patient had a small procedure-related intracerebral hemorrhage. Mean follow-up period was 26 months.

CONCLUSIONS

Early detection of AVF components of CAVMs prior to SRS may be difficult, particularly those in a central location. However, most AVFs became evident and showed consistency in angiographic morphology after obliteration of the majority nidus parts of CAVMs. Endovascular embolisation is effective in managing these AVF components.

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.

Safety and Efficacy of Onyx Embolization for Pediatric Cranial and Spinal Vascular Lesions and Tumors

BACKGROUND:

Although Onyx is widely used to embolize vascular lesions in adults, the safety and efficacy of this liquid embolic agent for use in children are not well studied.

OBJECTIVE:

To report our experience using Onyx in pediatric patients for a variety of cranial and spinal vascular lesions and tumors to determine its procedural complication rates, types, and clinical consequences and to highlight the indications for and principles of Onyx embolization in pediatric patients.

METHODS:

All pediatric Onyx embolization cases performed consecutively by the neuroendovascular services at our 2 institutions over a 5-year period were collected retrospectively and analyzed.

RESULTS:

Over the study period, 105 Onyx embolization procedures were performed in 69 pediatric patients with a mean follow-up of 112 days. Fifty-two patients harbored “primary” vascular lesions (malformations, fistulas, etc), whereas 17 patients had tumors. Complications occurred in 25 of 105 procedures (23.8%) and included ischemic infarct (7), asymptomatic nontarget embolization (4), intracerebral hemorrhage (3), microcatheter-related vessel perforation (3), retained microcatheter (2), cerebral edema (2), dimethyl sulfoxide-induced pulmonary edema (2), facial ischemia (1), and contrast-induced bronchospasm (1). Neurological morbidity occurred transiently after 10 procedures (9.5%) and permanently after 2 procedures (1.9%). There were no procedure-related deaths. Statistical analysis revealed no predictors of complications among the multiple potential risk factors evaluated.

CONCLUSION:

Our experience suggests that Onyx can be used effectively for embolization of pediatric cranial and spinal vascular lesions and tumors with low permanent morbidity; however, attention must be paid to the technical nuances of and indications for its use to avoid potential complications.

Joint protection in haemophilia

Haemarthroses (intra-articular haemorrhages) are a frequent finding typically observed in patients with haemophilia. Diagnosis and treatment of these bleeding episodes must be delivered as early as possible. Additionally, treatment should ideally be administered intensively (enhanced on-demand treatment) until the resolution of symptoms. Joint aspiration plays an important role in acute and profuse haemarthroses as the presence of blood in the joint leads to chondrocyte apoptosis and chronic synovitis, which will eventually result in joint degeneration (haemophilic arthropathy). Ultrasonography (US) is an appropriate diagnostic technique to assess the evolution of acute haemarthrosis in haemophilia, although magnetic resonance imaging remains the gold standard as far as imaging techniques are concerned. Some patients experience subclinical haemarthroses, which eventually tend to result in some degree of arthropathy, especially in the ankles. Nowadays, the most effective way of protecting these patients is primary prophylaxis, which in practice changes severe haemophilia into moderate haemophilia, preventing or at least minimizing the occurrence of haemarthrosis. If primary prophylaxis is, for whatever reason not an option, secondary prophylaxis and enhanced on demand treatment should be considered. Two alternatives are available for inhibitor patients: (i) control of haemostasis using by-passing agents (rFVIIa or aPCCs) either as enhanced on demand treatment or secondary prophylaxis, as appropriate, following the same basic principles used for non-inhibitor patients and (ii) immune tolerance induction (ITI) to eradicate the inhibitor.

Acute respiratory distress syndrome after onyx embolization of arteriovenous malformation

Purpose. We report a case of a 60-year-old male who underwent sequential Onyx embolizations of a cerebral arteriovenous malformation (AVM) which we implicate as the most likely etiology of subsequent acute respiratory distress syndrome (ARDS). Methods. Case report and literature review. Results. Shortly after the second Onyx embolization procedure, the patient declined from respiratory failure secondary to pulmonary edema. Clinical entities typically responsible for pulmonary edema including cardiac failure, renal failure, iatrogenic volume overload, negative-pressure pulmonary edema, and infectious etiologies were evaluated and excluded. The patient required mechanical ventilatory support for several days, delaying operative resection. The patient met clinical and radiographic criteria for ARDS. After excluding other etiologies of ARDS, we postulate that ARDS developed as a result of Onyx administration. The Onyx copolymer is dissolved in dimethyl sulfoxide (DMSO), a solvent excreted through the lungs and has been implicated in transient pulmonary side effects. Additionally, a direct toxic effect of the Onyx copolymer is postulated. Conclusion. Onyx embolization and DMSO toxicity are implicated as the etiology of ARDS given the lack of other inciting factors and the close temporal relationship. A strong physiologic rationale provides further support. Clinicians should consider this uncommon but important complication.

Radiosurgical treatment planning of AVM following embolization with Onyx: possible dosage error in treatment planning can be averted

Treatment of arteriovenous malformations (AVM) of the brain is challenging due to the size and location of the nidus-proper and its proximity to the cerebrovascular circulation. Recent advances in catheter techniques and new embolization materials such as Onyx (a liquid agent that is less adhesive and slowly polymerizing) have increased the probability of achieving obliteration. When planning radiosurgical cases following such embolization, however, one must be cognizant of the distortions introduced by this novel substance on imaging studies. A sample of Onyx was irradiated to define the attenuation per mm thickness. The difference in attenuation compared to water was determined. Dose calculations were performed using 3 methods of inhomogeneity corrections. Homogeneous calculations were compared to "standard" heterogeneity corrections and to "modified" heterogeneity corrections by assigning individual electron densities to the normal brain and the Onyx. The difference between the attenuation of water in comparison to the Onyx was approximately 3% for beam energy of 6 MV. Best calculation results were achieved when using the modified inhomogeneity corrections which were based on the actual attenuation of the Onyx. The use of Onyx caused significant image artifact on MR and especially CT. As such, a correction must be manually introduced into the planning system to account for this potential error. Otherwise, dose calculation may be unreliable and could have dire consequences for patients receiving high doses of radiotherapy.

ENDOVASCULAR TREATMENT OF EXPERIMENTAL ANEURYSMS USING A COMBINATION OF THERMOREVERSIBLE GELATION POLYMER AND PROTECTION DEVICES

OBJECTIVE

We developed a new liquid embolic agent, an aqueous solution of thermoreversible gelation polymer (TGP) for the treatment of cerebral aneurysms. This polymer solution has the unique characteristics that allow it to solidify at a specific temperature without solvent. We performed an experimental aneurysm embolization using this liquid embolic agent with and without different protective devices to evaluate its technical feasibility for the treatment of aneurysms.

METHODS

Fourteen side-wall aneurysms were surgically constructed on 14 common carotid arteries of 7 swine. Embolizations were conducted in combination with balloon protection (balloon group, n = 4), microstent protection (stent group, n = 4), and microcoil and microstent protection (stent-coil group, n = 4). Two aneurysms were used as controls. One control aneurysm was not embolized, and the other received control stent placement only. Angiographic follow-up was performed on day 14 and was followed by histopathological evaluation.

RESULTS

Successful TGP solution delivery was conducted in all cases. Complete aneurysm occlusion was achieved in all cases without TGP migration. Follow-up angiograms demonstrated complete occlusion in the stent and stent-coil groups. A small recurrence was observed in the balloon group. Histopathological findings demonstrated neoendothelialization across the necks of the aneurysms.

CONCLUSION

Experimental aneurysms were safely embolized using TGP. Further modifications related to mechanical stability and long-term safety evaluation results are necessary before clinical application.

Onyx distal embolization in transarterial embolization of dural arteriovenous fistula with subtotally isolated transverse-sigmoid sinus. A case report

SUMMARY

We describe a 39-year-old woman with dural arteriovenous fistula in the region of transversesigmoid sinus.A combination approach was designed to treat the fistula but the balloon failed to pass the severely stenosed proximal end of a subtotally isolated sinus. Although successfully occlusion of most feeding arteries from a single arterial injection was achieved, Onyx was found to shift to the outflow tract of the right heart ventricle and then to the lung latterly on six month follow-up.

The role of selective angiographic embolization of the musculo-skeletal system in haemophilia

The incidence of haemarthrosis as a result of a spontaneous periarticular aneurysm in haemophilia is very low. In these circumstances, angiographic embolization might be considered as a promising therapeutic and coagulation factor saving option in joint bleeds not responding to replacement of coagulation factor to normal levels. Moreover, embolization should be considered as a possible treatment for postoperative pseudoaneurysms complicating total knee arthroplasty in haemophilia. However, the pathological process of aneurysmal bleeding and clotting factor replacement is entirely different. While embolization is the treatment of choice for some periarticular complications that may occur, it is by no means a panacea for all resistant periarticular bleeds in haemophilia or for postoperative bleeding which usually settles with clotting factor replacement. Another use of arterial embolization is for the treatment of haemophilic tumours of the pelvis, because they can act as a focus for infection and cause cutaneous fistulas. When they present perforations and infections of endogenous origin, their course is usually fatal. Suitable treatment has been investigated on numerous occasions, most of the literature agreeing that the only curative treatment is surgical resection. However, surgical resection after performing arterial embolization to reduce the vascularization of the pseudotumour is a good alternative, thereby reducing the size of the pseudotumour and the risk of bleeding complications during surgery. It is important to bear in mind that despite its efficacy, arterial embolization is an invasive procedure with a reported rate of complications up to 25% (16% minor, 7% serious, 2% death).