Treatment of brain arteriovenous malformations by embolization and radiosurgery

Abstract

Embolization was used to reduce the size of brain arteriovenous malformations (AVMs) prior to radiosurgical treatment in 125 patients who were poor surgical candidates or had refused surgery. Of these patients, 81% had suffered hemorrhage, and 22.4% had undergone treatment at another institution. According to the Spetzler-Martin scale, the AVMs were Grade II in 9.6%, Grade III in 31.2%, Grade IV in 30.4%, and Grades V to VI in 28.8% of the cases. Most embolizations were performed using cyanoacrylate delivered by flow-guided microcatheters. Radiosurgery was performed using a linear accelerator in 62 patients treated by the authors, and 34 patients were treated at other institutions using various methods. Embolization produced total occlusion in 11.2% of AVMs and reduced 76% of AVMs enough to allow radiosurgery. Radiosurgery produced total occlusion in 65% of the partially embolized AVMs (79% when the residual nidus was < 2 cm in diameter). Embolizations resulted in a mortality rate of 1.6% and a morbidity rate of 12.8%. No complications were associated with radiosurgery. The hemorrhage rate for partially embolized AVMs was 3% per year. No patient with a completely occluded AVM experienced rehemorrhage. Angiographic follow-up review of AVMs embolized with cyanoacrylate demonstrated a 11.8% revascularization rate, occurring within 1 year. It is concluded that after partial embolization with cyanoacrylate, the risk of hemorrhage from the residual nidus is comparable to the natural history of AVMs and that the residual nidus can be irradiated with results almost as good as for a native AVM of the same size.

Role of Embolization for Cerebral Arteriovenous Malformations

“…47 Gobin et al have reported that preradiosurgical embolization reduced average AVM volumes by more than 30% in their cohort of 125 patients and allowed for a 65% rate of AVM cure in the patients rendered suitable for radiosurgery after embolization. 48 Obliteration rates of 60% to 81% have been reported by other groups. 41 It is noteworthy, however, that a number of reports indicate a negative association between successful AVM radiosurgical obliteration and previous embolization.…”

“…Such patients typically have small AVMs with few feeding pedicles, noncompartmental fistulous (rather than plexiform) niduses, and no perinidal angiogenesis. 18,41,42,48,54 Additionally, use of Onyx has been associate with higher rates of AVM cure by embolization than previously seen with other embolic agents. 41 …”

Does treatment with N-butyl cyanoacrylate embolization protect against hemorrhage in cerebral arteriovenous malformations?

“…Concerning obliteration rate, the multivariate analysis clearly shows that lesions with less than 2/3 obliteration had proportionally higher rebleeding rates. Gobin did not observe this association in partially embolized patients who later underwent radiosurgery, but this might be explained by the fact that in that study a multivariate technique was not used for data analysis 22 . Our patients with less than 1/3 obliteration bled even more often than expected had the lesion been untreated.…”

“…it is exactly in small lesions that embolization has the highest rates of cure 8,22 . Luessenhop 16 observed that partial embolization may reduce the risk of hemorrhage by reducing intranidal pressure.…”

“…Luessenhop 16 observed that partial embolization may reduce the risk of hemorrhage by reducing intranidal pressure. However, the reports found in the literature so far are inconclusive concerning the protective role of partial embolization 7,12,16,18,23 , since any residue of malformed vessels has the potential to cause future bleeding, no matter what percentage of the lesion was obliterated 15,18,22,23 . Partial embolization has also been thought to increase the risk of cAVM rupture, even in patients without a previous hemorrhagic event 8,10 .…”