Dural arteriovenous fistulas of the posterior fossa draining into subarachnoid veins.

PURPOSE To describe the clinical presentation, angioarchitecture, and risks and problems of therapy in patients with dural arteriovenous malformations of the posterior fossa draining into subarachnoid veins. PATIENTS AND METHODS Twelve patients with dural arteriovenous malformations of the posterior fossa draining into subarachnoid veins were studied. RESULTS These fistulas often presented with intracranial hemorrhage (eight cases) and myelopathy (two cases). They were located in the tentorium (six cases) or at the skull base (six cases). The arterial supply was provided by branches of the external carotid artery (nine cases), by the posterior meningeal branch of the vertebral artery (nine cases), and by the meningohypophyseal trunk (three cases). The fistulas drained directly into a cortical vein (six cases) or into a venous lake (six cases). In two cases, perimedullary draining veins were observed. The treatment modalities were endovascular embolization alone (two cases), surgery alone (five cases), and embolization followed by surgery (three cases). Despite the treatment, four patients died; in two cases, intracranial hemorrhage recurred. CONCLUSIONS Subtotal occlusion of a fistula by surgery or embolization alone is not protective against further complications, especially hemorrhage. The goal of treatment is to achieve a rapid and complete anatomical cure; combined endovascular and neurosurgical treatment seems to be the therapeutic choice.