Preoperative Onyx embolization of a giant cavernous malformation involving the dural sinuses

Cavernous malformations (CMs) or hemangiomas arising from within the dural sinuses are rare entities that differ from their parenchymal counterparts in that they are highly vascular lesions. While parenchymal CMs are typically angiographically occult, intrasinus malformations may have large, dural-based arterial feeding vessels that are amenable to preoperative embolization. The novel liquid embolic Onyx (ev3, Inc.) is an ideal agent for the embolization of these lesions. The authors present the first known case of a giant intrasinus CM embolized with Onyx before gross-total resection. The authors report the case of a 9-year-old boy with brief apneic episodes in whom MR imaging revealed a giant CM arising from within the right transverse and sigmoid sinuses and infiltrating the right tentorium cerebelli. At another institution, the patient had undergone 1 prior embolization and 2 unsuccessful attempts at resection. Both surgeries had been complicated by massive blood loss and were aborted. Under the authors' care, the patient underwent preoperative transarterial embolization with Onyx during which a substantial volume of the mass lesion was filled with embolisate. Subsequently, complete circumferential excision of the mass from the tentorium was accomplished with minimal intraoperative blood loss.