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

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). Historically, pure surgical treatment for high-grade AVMs is flawed prohibitive morbidity and mortality, and has been largely abandoned. Ujiiye et al1 presented a series of seven patients of grade V AVMs treated with surgery alone. Four of these patients developed hemorrhagic complications either during surgery or postoperatively. However, in recent years this dogma has been challenged with the development of endovascular techniques. Although very large AVM are still challenging, especially in eloquent brain, occlusion was made possible by multimodality therapy, including a combination of embolization, radiosurgery, and/or microsurgical resection. Natraj et al presented their experience in the mult imodality management of cerebral vascular malformations spanning 20 years.2 Total 265 patients underwent surgery/embolizat ion/radiosurgery or combination of them. Using a multimodality approach, the authors were able to cure 92% of treated SpetzlerMartin grades I to IV lesions but only 53% of treated Spetzler-Martin grade V lesions. Increasing age, SpetzlerMartin grade, and rehemorrhage were correlated with a poorer Glasgow Outcome Scale score. van Rooij et al described their initial experience with onyx embolization