Curative Embolization for Pediatric Spetzler-Martin Grade III Cerebral Arteriovenous Malformations

OnyxTMGel or Coil versus Hydrogel as Embolic Agents in Endovascular Applications: Review of the Literature and Case Series

This review focuses on the use of conventional gel or coil and "new" generation hydrogel used as an embolic agent in endovascular applications. In general, embolic agents have deep or multidistrict vascular penetration properties as they ensure complete occlusion of vessels by exploiting the patient's coagulation system, which recognises them as substances foreign to the body, thus triggering the coagulation cascade. This is why they are widely used in the treatment of endovascular corrections (EV repair), arteriovenous malformations (AVM), endoleaks (E), visceral aneurysms or pseudo-aneurysms, and embolisation of pre-surgical or post-surgical (iatrogenic) lesions. Conventional gels such as Onyx or coils are now commercially available, both of which are frequently used in endovascular interventional procedures, as they are minimally invasive and have numerous advantages over conventional open repair (OR) surgery. Recently, these agents have been modified and optimised to develop new embolic substances in the form of hydrogels based on alginate, chitosan, fibroin and other polymers to ensure embolisation through phase transition phenomena. The main aim of this work was to expand on the data already known in the literature concerning the application of these devices in the endovascular field, focusing on the advantages, disadvantages and safety profiles of conventional and innovative embolic agents and also through some clinical cases reported. The clinical case series concerns the correction and exclusion of endoleak type I or type II appeared after an endovascular procedure of exclusion of aneurysmal abdominal aortic (EVAR) with a coil (coil penumbra released by a LANTERN microcatheter), the exclusion of renal arterial malformation (MAV) with a coil (penumbra coil released by a LANTERN microcatheter) and the correction of endoleak through the application of Onyx 18 in the arteries where sealing by the endoprosthesis was not guaranteed.

Deliberately Staged Combined Endovascular Embolization and Subsequent Microsurgery Resection for the Treatment of Cerebral Arteriovenous Malformations

OBJECTIVE

Complex cerebral arteriovenous malformations (AVMs) require a combined therapy of endovascular embolization and microsurgical resection to eliminate the lesion and maximize neurological protection, while a deliberate time interval might contribute to optimal clinical outcomes. The present study aimed to explore the feasibility of this paradigm.

METHODS

All patients who underwent deliberately planned presurgery embolization and microsurgery resection between 2015 and 2023 were reviewed, with baseline data, postoperative complications, and follow-up outcomes recorded. The modified Rankin scale (mRS) was used to evaluate clinical outcomes, with mRS 0-2 defined as good.

RESULTS

A total of 30 patients were included in the study (15 were ruptured AVMs). The median Spetzler-Martin grade of baseline AVMs was 3 (interquartile range: 2-3). The median interval between the last embolization and microsurgery was 5 days (interquartile range: 2.25-7). The complete removal rate was 100%, and the overall permanent complication rate was 16.67%. At the last follow-up, 26 patients achieved mRS 0-2, while 28 had improved or unaltered mRS. The last follow-up mRS significantly improved from baseline and discharge (P = 0.0006 and P = 0.006). The last follow-up mRS decreased by 0.65 for each additional day of time interval before the 4.4-day inflection point (β = -0.65, P = 0.02) in the AVM ruptured cohort.

CONCLUSIONS

The deliberately staged combined procedure of embolization and microsurgery might be a safe and efficacious strategy for Spetzler-Martin grade 2-5 AVMs, 4-5 days might be an appropriate staged time interval for ruptured AVMs, although further studies are needed to substantiate these findings.

Worldwide Research Trends on Transvenous Embolization of Brain Arteriovenous Malformations: A Bibliometric and Visualized Study

BACKGROUND

Transvenous embolization (TVE) of brain arteriovenous malformations (bAVMs) is an emerging endovascular technique that has shown high cure rates in selected cases. The rationale of our study was to determine authorship and worldwide institutional trends and contributions to the knowledge in this topic.

METHODS

Web of Science database was used. A total of 63 articles were included based on predefined inclusion criteria, which were manually reviewed. The bibliometric analysis involved the use of quantitative bibliometric indicators and network analysis with co-authorship and co-occurrence of terms, which were performed using the bibliometrix package in R and VOSviewer, respectively.

RESULTS

The first article was published in 2010, with the largest number of articles published in 2022 (10 articles). The average number of citations per document was 11.38, and the annual growth rate was 14.35%. The top 10 authors with the most scientific production on TVE of bAVMs were from France, and the most cited study was published by Iosif C in 2015, followed by Consoli A in 2013, and Chen CJ in 2018. Journal of Neurointerventional Surgery was the journal with the most articles published. The most commonly used keywords were dural arteriovenous fistula, Onyx, vascular disorders, and neurological surgery around 2016, and intervention around 2021.

CONCLUSIONS

TVE of bAVMs is an emerging technique. Our search identified some scientific articles, without randomized clinical trials, but many case series from single institutions. French and German institutions are the pioneers in the field, and further research is required in specialized endovascular centers.

Curative embolization of ruptured pediatric cerebral arteriovenous malformations

INTRODUCTION

Embolization with the intention to cure has not been well studied in ruptured arteriovenous malformations (AVMs). Furthermore, the role of primary curative embolization of pediatric AVMs is uncertain. Hence, we aimed to characterize the safety and efficacy of curative embolization of ruptured pediatric AVMs and assess predictors of obliteration and complications.

METHODS

A retrospective analysis of all pediatric (≤18 years) patients who underwent curative embolization of ruptured AVMs was conducted in two institutions between 2010 and 2022. The efficacy (complete angiographic obliteration after the last embolization session), recurrence (radiological recurrence of the lesion after confirmed obliteration in follow-up imaging), and safety (procedure-related complications and mortality) of the procedure were evaluated.

RESULTS

Sixty-eight patients (38 females; mean age 12.4 ± 3.4 years) underwent a total of 109 embolization sessions. Median follow-up time was 18 months after embolization (ranged from 2 to 47 months). Complete angiographic obliteration was achieved in 42 patients (62%). In 30 patients (44%) the AVM was occluded with a single embolization session. Recurrence of a totally embolized lesion occurred in 9 patients (13%). Thirteen complications (11.9% of procedures) were observed, and no deaths were reported. A nidus size > 2 cm was the only independent predictor of complete obliteration (OR = 0.16; 95% CI 0.03 - 0.77; p = 0.030).

CONCLUSION

Embolization of pediatric ruptured AVMs with curative intent can achieve acceptable obliteration rates. However, recurrence after complete obliteration and procedure-related complications of curative embolization of these lesions cannot be ignored. Ruptured AVMs ≤ 2 cm are adequate to achieve complete obliteration with curative endovascular management.

Intra- and post-operative acute hemorrhagic complications of Onyx embolization of brain arteriovenous malformations: A single-center experience

Background

The intra- and post-operative acute (within 72 h) hemorrhagic complications of endovascular treatment (EVT) for a brain arteriovenous malformation (BAVM) are disastrous. Thus, further experiential summaries are required to fully understand them.

Materials and methods

This was a retrospective study of 25 patients with consecutive BAVM who were treated via EVT with Onyx embolization and suffered intra- and post-operative acute hemorrhage. The clinical and imaging data of the patients were recorded, analyzed, and discussed.

Result

Twenty-five patients were aged 11–70 years (mean, 37.2 ± 16.1 years), of whom 12 were female (48%, 12/25). Of the 25 hemorrhagic complications, 17 (68%, 17/25) were intraoperative, and 8 (32%, 8/25) were post-operative and occurred between 1 and 12 h after EVT. Of 17 intraoperative hemorrhages, 13 (76.5%, 13/17) were due to high-pressure Onyx casting. Of eight post-operative hemorrhages, six (75%, 6/8) were attributed to normal perfusion pressure breakthrough. The degree of nidus Onyx embolization was more than 2/3 or complete in seven (87.5%, 7/8) BAVMs. Draining vein occlusion was observed in eight (32%, 8/25) of 25 BAVMs. After hemorrhage, conservative treatment was administered in 12 (48%, 12/25) cases, and surgical management was performed in other cases. There were eight cases of mortality; the remaining 17 patients had follow-up data. Among them, 15 patients had good outcomes, with Glasgow Outcome Scale scores of 5 and 4, accounting for 60% (15/25).

Conclusion

In EVT for BAVMs, intra- and post-operative acute hemorrhagic complications are disastrous; only 60% of patients have a good outcome. Therefore, high-pressure Onyx casting or casting too much Onyx at one time to pursue a high degree of nidus embolization should be performed cautiously, and primary draining vein occlusion should be avoided. In short, EVT needs to be performed carefully.