Use of Onyx for endovascular embolization of pediatric spinal perimedullary (Type IV) fistula: case report.

The definitive treatment of perimedullary arteriovenous fistulas (PMAVFs) is warranted in view of the progressive neurologic decline noted with the conservative mode of management. The treatment options include microsurgical excision, endovascular embolization, or a multimodal approach. Because of the relatively larger size of the feeding arteries in type B and C PMAVFs, an endovascular approach is usually feasible. However, the endovascular treatment for type A lesions is technically challenging in view of near normal sized arterial feeders. Endovascular embolization using n-butyl cyanoacrylate is described; however, successful use of liquid embolic agents such as onyx or squid is not previously documented.The described 3 cases initially presented with insidious onset and gradually progressive paraparesis, paresthesia, and urinary symptoms. The imaging (magnetic resonance and digital subtraction angiography) revealed type A PMAVFs. The microcatheter could be successfully navigated close to the fistulous site, and complete obliteration of the fistula was achieved using ethylene vinyl alcohol copolymer (EVOH)–based liquid embolic agent, squid in all of our cases. The occlusion remained durable, and patients showed steady neurologic improvement in the follow-up period.Endovascular embolization of type A PMAVF using EVOH-based liquid embolic agent is feasible and could be considered as an effective alternative to surgery.