Head and neck hypervascular lesions: Embolization with ethylene vinyl alcohol copolymer - Laboratory evaluation in swine and clinical evaluation in humans

PURPOSE: (a) To assess in swine long-term (12-month) histopathologic change s, particularly, those related to recanalization and angiotoxicity after en dovascular delivery of ethylene vinyl alcohol copolymer (EVAC), and (b) to evaluate initial clinical experience in 18 patients with head and neck tumo rs and arteriovenous malformations. MATERIALS AND METHODS: Embolization with EVAC was performed in one rete eac h in five swine. After 12 months, an angiogram was obtained, and the contra lateral rete was also embolized (acute). Swine were sacrificed and the reti a harvested for pathologic examination. In the clinical study, 18 patients with tumors (n = 14), facial arteriovenous malformations (n = 3), and verte bral arteriovenous fistula (n = 1) underwent therapeutic embolization. The technical aspects of EVAC embolization, percentage of occlusion, and clinic al complications were evaluated. RESULTS: Angiographic 12-month follow-up in swine revealed persistent occlu sion of the embolized rete or retia. Histologic examination of the same ret e showed vascular occlusion and moderate intraluminal foreign body giant ce ll reaction; the acutely embolized rete showed no endothelial denudation or angionecrosis. Clinical evaluation in patients revealed satisfactory penet ration of lesion vasculature with EVAC when the microcatheter was advanced within 2 cm of a lesion or when percutaneous puncture was performed. There were two transient complications: one increase in a preexisting fifth nerve palsy and one increase in preexisting hemiparesis. CONCLUSION: EVAC is a promising liquid embolic material providing long-term occlusion of blood vessels.