Preoperative Onyx embolization of a large facial intraosseous cavernous venous malformation.

Intraosseous cavernous venous malformations of the facial bones, though rare, pose significant surgical challenges due to the high risk of intraoperative hemorrhage. Preoperative embolization can decrease vascular flow to the lesion and mitigate the risk of hemorrhage during resection. However, access to an appropriate feeder vessel is not always possible. In such cases, alternative approaches to embolization must be explored. We report a case of a 74-year-old woman with a long-standing zygomaticomaxillary intraosseous cavernous venous malformation who underwent surgical debulking after direct percutaneous intralesional injection of Onyx-18 (6% ethylene-vinyl alcohol copolymer, Medtronic Neurovascular, Irvine, CA). The procedure resulted in minimal intraoperative bleeding and facilitated successful debulking of the lesion to improve the patient's symptoms and cosmesis. This case highlights the utility of direct ethylene vinyl alcohol copolymer embolization of intraosseous vascular malformations as a safe and effective alternative when standard embolization techniques are not viable.