Bilateral ethmoidal dural arteriovenous fistulae: a previously unreported entity: case report.

OBJECTIVE AND IMPORTANCE: Ethmoidal dural arteriovenous fistulas (AVFs) are rare intracranial lesions associated with a high risk of intracranial hemorrhage. Reported hemorrhage rates have ranged from 62 to 91%, and an aggressive clinical course is more likely than a benign clinical course. We describe the first case of a patient with bilateral ethmoidal dural AVFs.CLINICAL PRESENTATION: A 50-year-old man presented with posterior fossa subarachnoid hemorrhage and cerebellar intraparenchymal hemorrhage. Angiography revealed a tentorial AVF and a complex anterior ethmoidal dural AVF.INTERVENTION: The tentorial AVF was treated with preoperative embolization and surgical obliteration. On follow-up angiography, the ethmoidal dural AVF was not considered amenable to embolization. A right modified orbitozygomatic approach was performed and the right-sided fistula was interrupted. Intraoperative angiography revealed obliteration of the right-sided fistula, but a persistent fistula on the left. Further surgical exploration revealed this contralateral anterior ethmoidal dural AVF, which was clip ligated. No residual fistula was noted on intraoperative angiography.CONCLUSION: Anterior ethmoidal dural AVFs may occur bilaterally. Given their complex angiographic appearance, their presence bilaterally may not be readily apparent on preoperative angiography. Intraoperative angiography is crucial to identify a contralateral fistula and to verify that ligation has been curative.