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• The Impact of Endovascular Onyx Embolization on Acutely Ruptured Intracranial Arteriovenous Malformations
  Dale Ding
  Published on: 13 April 2016

• Published on: 13 April 2016

  The Impact of Endovascular Onyx Embolization on Acutely Ruptured Intracranial Arteriovenous Malformations

  • Dale Ding

  I have read, with great interest, the paper by Stemer et al. titled 'Acute embolization of ruptured brain arteriovenous malformations' [1]. The authors describe a cohort of 21 patients with ruptured intracranial arteriovenous malformations (AVM) who were treated with endovascular Onyx (ev3, Irvine, California, USA) embolization in the acute phase following hemorrhage. The median interval from hemorrhagic presentation to...

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  I have read, with great interest, the paper by Stemer et al. titled 'Acute embolization of ruptured brain arteriovenous malformations' [1]. The authors describe a cohort of 21 patients with ruptured intracranial arteriovenous malformations (AVM) who were treated with endovascular Onyx (ev3, Irvine, California, USA) embolization in the acute phase following hemorrhage. The median interval from hemorrhagic presentation to treatment was 4 days (range 0-19 days). Thirteen patients received a single treatment (62%), and eight patients were treated in more than one stage (38%). Complete occlusion was achieved in 11 patients (52%) including seven in one stage and four in multiple stages. There were two asymptomatic intraprocedural complications (10%) as well as two mortalities unrelated to treatment (10%).

  Excluding three patients lost to follow-up and six patients who underwent post-embolization surgical resection, 12 patients had angiographic follow-up at a mean interval of 7.5 months. It would be interesting to know the number of AVMs, if any, which had post- embolization recanalization at follow-up as this is known to occur at varying time intervals following endovascular treatment. Despite high levels of initial enthusiasm for complete AVM cure with standalone endovascular embolization following the advent and subsequent widespread therapeutic use of permanent liquid embolic agents, especially Onyx, the role of embolization in the overall management of AVMs remains largely adjunctive.

  Studies reporting high rates of complete AVM obliteration with embolization alone, approaching 50%, were subject to significant selection biases [2]. Total obliteration rates of 10-20% with embolization alone are more reflective of less selected AVM cohorts [3]. The effect of partial AVM treatment on the subsequent hemorrhage risk is still controversial with conflicting studies reporting improved and worsened outcomes of incompletely obliterated AVMs. With increasing evidence that embolization reduces AVM obliteration rates following radiosurgery, judicious use of endovascular therapy for AVMs is crucial to the optimal long-term management of these complex vascular lesions [4-6].

  Early natural history studies of AVMs did not distinguish ruptured from unruptured lesions. However, several recent studies in the past decade have repeatedly demonstrated that the hemorrhage risk of ruptured AVMs is significantly higher than the hemorrhage risk of unruptured ones [7]. Unlike intracranial aneurysms, for which the risk of acute repeat hemorrhage following initial rupture is well described, the acute rehemorrhage rate of ruptured AVMs is poorly defined. In a recent meta- analysis of over 3900 patients, Gross et al. reported an annual hemorrhage risk of 4.5% for ruptured AVMs compared to 2.2% for unruptured lesions [8]. A follow-up duration of less than one year, such as in this study, is inadequate to compare treatment outcomes to the natural history.

  In summary, the authors should be congratulated for demonstrating the feasibility and safety of endovascular Onyx embolization for the treatment of acutely ruptured AVMs. As the authors note, the study is significantly limited by the relatively small number of patients with angiographic follow-up and the relatively short duration of follow-up. Therefore it remains to be determined in larger cohorts with longer follow-up whether the strategy of acute embolization for ruptured AVMs is superior to current approaches which are largely conservative in the acute post- hemorrhage phase.

  References

  1. Stemer, A.B., W.O. Bank, R.A. Armonda, A.H. Liu, D.W. Herzig, and R.S. Bell, Acute embolization of ruptured brain arteriovenous malformations. J Neurointerv Surg, 2013. 5(3): p. 196-200. 2. Saatci, I., S. Geyik, K. Yavuz, and H.S. Cekirge, Endovascular treatment of brain arteriovenous malformations with prolonged intranidal Onyx injection technique: long-term results in 350 consecutive patients with completed endovascular treatment course. J Neurosurg, 2011. 115(1): p. 78-88. 3. van Rooij, W.J., M. Sluzewski, and G.N. Beute, Brain AVM embolization with Onyx. AJNR Am J Neuroradiol, 2007. 28(1): p. 172-7; discussion 178. 4. Schwyzer, L., C.P. Yen, A. Evans, S. Zavoian, and L. Steiner, Long-term Results of Gamma Knife Surgery for Partially Embolized Arteriovenous Malformations. Neurosurgery, 2012. 71(6): p. 1139-48. 5. Ding, D., C.P. Yen, Z. Xu, R.M. Starke, and J.P. Sheehan, Radiosurgery for patients with unruptured intracranial arteriovenous malformations. J Neurosurg, 2013. 6. Andrade-Souza, Y.M., M. Ramani, D. Scora, M.N. Tsao, K. terBrugge, and M.L. Schwartz, Embolization before radiosurgery reduces the obliteration rate of arteriovenous malformations. Neurosurgery, 2007. 60(3): p. 443-51; discussion 451-2. 7. Stapf, C., H. Mast, R.R. Sciacca, J.H. Choi, A.V. Khaw, E.S. Connolly, J. Pile-Spellman, and J.P. Mohr, Predictors of hemorrhage in patients with untreated brain arteriovenous malformation. Neurology, 2006. 66(9): p. 1350-5. 8. Gross, B.A. and R. Du, Natural history of cerebral arteriovenous malformations: a meta-analysis. J Neurosurg, 2013. 118(2): p. 437-43.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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