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Introduction
Onyx (ev3 Neurovascular, Irvine, California, USA) is a non-adhesive liquid embolic agent that is comprised of ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide. It is approved for presurgical embolization of brain arteriovenous malformations (Onyx 18 and 34) and for the treatment of wide necked sidewall aneurysms (Onyx HD-500) but has been utilized for numerous off-label applications. Like n-butyl cyanoacrylate glue, Onyx has been used for parent vessel sacrifice to treat peripheral cerebral mycotic and dissecting aneurysms. 1 These treatments may be complicated by small infarcts which are generally asymptomatic or minimally symptomatic. 2 On the other hand, therapeutic occlusion of a proximal vessel such as the internal carotid or vertebral artery (VA) is typically performed with coils because liquid agents pose the risk of a significant embolic stroke. We describe the novel use of Onyx for endovascular closure of a dissecting pseudoaneurysm of the intracranial VA.
Case report
A middle aged patient presented with obtundation (high grade Hunt and Hess score) and was found to have diffuse posterior fossa subarachnoid and intraventricular hemorrhage associated with a large right cerebellar and hemi-medullary infarct ( figure 1A-C ). CT angiography demonstrated a dissecting aneurysm of the right intradural VA involving the origin of the posterior inferior cerebellar artery (PICA) ( figure 1D ). The patient was taken for urgent endovascular treatment.
The procedure was performed under general anesthesia. No intravenous heparin was given due to the elevated risk of bleeding within the infarct. Diagnostic angiography was performed to assess collateral circulation and revealed robust posterior communicating arteries and a dominant left VA. There was antegrade flow within the right PICA which arose from the midportion of the pseudoaneurysm, proximal to an intra-aneurysmal focus of severe narrowing ( figure 2 ). The anterior spinal artery was not visualized from the right VA. Given the infarct involvement of the entire PICA territory, including the medulla, it was deemed unnecessary to preserve the right PICA, and the therapeutic goal was endovascular trapping using coils. However, attempts to advance the 0.010 inch X-Pedion microwire (ev3 Neurovascular) past the region of intra-aneurysmal stenosis were unsuccessful and were abandoned due to the risk of perforation.
In order to avoid manipulation of the dominant left VA, it was decided...