Combined Microneurosurgical and Endovascular Management of Grade V Occipital Arteriovenous Malformation: Sequential Delayed Embolization Holds the Key!

Abstract

A 26-year-old previously healthy woman presented with complaints of sudden-onset headache, decreased level of consciousness, right hemiparesis, and hemianopia. Computed tomography (CT) of the head showed a leftsided parietal hematoma (►Fig. 1). CT angiography showed a complex arteriovenous malformation (AVM) with a venous varix in the center of the hematoma. Cerebral angiogram revealed a grade V AVM in the left parieto-occipital region measuring 6 4 cm and supplied by left posterior cerebral artery (PCA) and middle cerebral artery (MCA) and draining into superior sagittal sinus (SSS) and straight sinus via internal occipital vein/vein of Galen (►Fig. 2). Elective sequential endovascular embolization of the nidus was planned over 3 months in four settings. The aim of partial embolization over weeks was to occlude deep feeders and reduce the nidus to allow definitive treatment, either surgical resection or radiosurgery. Gradual flow reduction should also help prevent normal perfusion pressure breakthrough (NPPB) that might happen due to sudden hemodynamic changes during rapid occlusion of large, highflow AVMs. The treatment plan was developed in a way that each embolization would occlude less than 40% of the arterial feeders and nidus penetration would be limited. MCA feeders were embolized first, followed by the PCA feeders. Onyx (Covidien; Irvine, California, United States) was used in all sessions. It is composed of EVOH (ethylene vinyl alcohol) copolymer dissolved in DMSO (dimethyl sulfoxide), and suspended micronized tantalum powder to provide contrast for visualization under fluoroscopy. Standard technique was used with Apollo catheters with Mirage guidewires (Covidien; Irvine, California, United States) and Onyx 18 and 34 was injected into the nidus. The choice between 18 and 34 was based on flow characteristics observed during the superselective angiograms. At the end of last session of embolization, only small superficial cortical MCA and PCA feeders were left patent (►Fig. 3). The little flow lead to the decision to surgically excise the nidus. The patient underwent left-sided occipital craniotomy and excision of the nidus without complications (►Fig. 4). Postoperative angiogram showed complete resection (►Fig. 5).