INTERVENTIONAL NEURORADIOLOGY Curative embolization of cerebral arteriovenous malformations (AVMs) with Onyx in 101 patients Vasilios Katsaridis & Chrysanthi Papagiannaki & Enrico Aimar Received: 4 January 2008 / Accepted: 29 February 2008 / Published online: 12 April 2008 # Springer-Verlag 2008 Abstract Introduction Onyx has emerged in the recent years as a new embolic material. We present our experience with Onyx in the curative embolization of brain cerebral arteriovenous malfor- mations (AVMs). Methods We retrospectively reviewed the files of all patients that we had treated with Onyx embolic material for a brain AVM during the last 4 years. We identified 101 patients who underwent a total of 219 sessions of embolization. Results The treatment has been concluded in 52 patients; in this group, total occlusion was obtained in 28 (53.9%) patients and near-total occlusion was obtained in 18 (34.6%). The respective figures based on the 101 patients of the study cohort are 28/101 (27.7%) and 18/101 (17.8%). More embolization sessions are to be carried out on the remaining 49 patients. There were three deaths, and eight patients had permanent neurological deficits with a result- ing morbidity of 8% and mortality of 3%. Conclusion High rates of total or near-total occlusion of brain AVMs can be achieved with multiple sessions of Onyx embolization with acceptable morbidity and mortality Keywords Arteriovenous malformation . Brain . Embolization . Onyx Introduction The treatment of brain arteriovenous malformations (AVMs) includes different modalities (endovascular treat- ment, surgical removal, radiosurgery) either alone or in combination. Until recently, the standard endovascular treatment con- sisted of embolization with particles or n-butyl-cyanoacrylate glue (NBCA). However, embolization with particles has not been very effective partially because it has proven impossi- ble to inject particles through the small lumen micro- catheters that are large enough to reach the distal location of the AVM and partially because that the particles are associated with a high rate of recanalization. Arteriovenous malformation embolization with NBCA requires consider- able experience since the material polymerizes very quickly and proximal occlusion consisting of an inadequate penetra- tion to the malformation and micro-catheter gluing in the vessel can occur. Furthermore, since the amount of glue that can be injected through the micro-catheter is limited, multiple catheterizations of the malformation are necessary to achieve a high rate of occlusion. These multiple catheter- izations can significantly augment the duration of the intervention as considerable time can be spent trying to reach the AVM with a new micro-catheter [1–4]. Onyx (ev3 Neurovascular, Irvine, CA) was introduced a few years ago as a new embolic material for the endovas- cular treatment of brain AVMs. It consists of an ethyl-vinyl copolymer dissolved in dimethyl-sulfoxide (DMSO) with tantalum powder added for radio-opacity. Its slow solidifi- cation allows for a more prolonged and controlled injection that enables larger parts of the malformation being occluded with each micro-catheterization. It also offers long injection times, possibility for angiographic control and assessment and continuation of the injection until the desired result is achieved [5]. Many centers have employed embolization only as a pre- surgical or pre-radiosurgical measure and not with the aim of achieving the complete occlusion of the AVM [3, 4, 6–11]. Neuroradiology (2008) 50:589–597 DOI 10.1007/s00234-008-0382-x V. Katsaridis (*) : C. Papagiannaki : E. Aimar Neurosurgical Department, “G. Papanikolaou” General Hospital, 15, Papanikolaou Ave., Thessaloniki 57010, Greece e-mail: vkats@iname.com