The failure of preoperative ethylene-vinyl alcohol copolymer embolization to improve outcomes in arteriovenous malformation management: case series

Clinical article

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Ethylene-vinyl alcohol copolymer embolization is increasingly used preoperatively in the resection of brain arteriovenous malformations (AVMs). However, the case for embolization improving the outcome of resection has not been evaluated. In this paper the authors set out to compare outcomes after surgery for brain AVMs in 2 consecutive periods of practice. In the first period, selective embolization was used without the use of ethylene-vinyl alcohol copolymer. In the second period, selective embolization with ethylene-vinyl alcohol copolymer was performed.


A consecutive case series (prospectively collected data) was retrospectively analyzed. Adverse outcomes were considered to be an outcome modified Rankin Scale score greater than 2 due to embolization or surgery.


A total of 538 surgical cases were included. The percentages of adverse outcomes were as follows: 0.34% for Spetzler-Martin AVMs less than Grade III (1 of 297 cases); 5.23% (95% CI 2.64%–9.78%) for Grade III AVMs (9 of 172 cases); and 17% (95% CI 10%–28%) for AVMs greater than Grade III (12 of 69 cases). There was no improvement in outcomes from the first period to the second period. The adverse outcome for Grade III brain AVMs in the first period was 5.2% (7 of 135 cases) and in the second period (after ethylene-vinyl alcohol copolymer was introduced) it was 5.4% (2 of 37 cases). For AVMs greater than Grade III, the adverse outcome was 12% (6 of 49 cases) in the first period and 30% (6 of 20 cases) in the second period.


Outcomes for brain AVM surgery were not improved by ethylene-vinyl alcohol copolymer embolization. Preoperative embolization of high-grade AVMs with an ethylene-vinyl alcohol copolymer did not prevent those hemorrhagic complications which embolization is hypothesized to prevent based on theoretical speculations but not demonstrated in practice.

Abbreviations used in this paper:AVM = arteriovenous malformation; EVACE = ethylene-vinyl alcohol copolymer embolization; GOS = Glasgow Outcome Scale; mRS = modified Rankin Scale.

Article Information

Address correspondence to: Michael K. Morgan, M.D., Health and Medical Development, Macquarie University, 2 Technology Place, Sydney, New South Wales 2109, Australia. email:

Please include this information when citing this paper: published online January 25, 2013; DOI: 10.3171/2012.11.JNS112064.

© AANS, except where prohibited by US copyright law.



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    Case series of more than 40 patients reporting disabling morbidity who underwent embolization for a brain AVM. Outcomes included severe permanent disability (mRS score > 2, Barthel Index < 50, GOS score < 5, or a rating of “severe”), death, and emergency surgery. Spetzler-Martin Grades I/II, III, and IV/V were seen in 41.3%, 32.2%, and 26.5%, respectively, of all cases. Twenty-seven percent of AVMs were completely obliterated. The horizontal lines represent the 95% CI, with the small vertical line in the center indicating the point estimate. The dotted line represents the mean from all series (6.6%). n = number of patients.

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    Left: Adverse outcomes from surgery during the 2 consecutive periods as stratified by Spetzler-Martin (SM) grade clusters. The vertical lines indicate the 95% CIs. The horizontal lines within the 95% CIs represent the point estimates, which are also given as percentages. Right: Adverse outcomes due to intraoperative hemorrhage or hemorrhage in the brain AVM bed following surgery for Spetzler-Martin AVMs Grade III or higher are provided for those who underwent embolization and those who did not for each of the 2 consecutive periods. The vertical lines represent the upper limits of the 95% CIs. The tops of the boxes represent the point estimates, which are also given as percentages. Period 1 represents the pre-EVACE period (15% [65 of 445] cases underwent embolization). Period 2 represents the EVACE period (27% of 93 cases underwent embolization).


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