Dural arteriovenous fistula of the posterior fossa draining into the spinal medullary veins--an unusual cause of myelopathy: case report.

In a 31-year-old male patient suffering from progressive myelopathy, a right carotid angiography disclosed an intracranial tentorial arteriovenous fistula (AVF) draining intrathecally into the spinal medullary veins. An embolization via the afferent meningohypophyseal artery was not technically feasible, and a microsurgical excision of the AVF was accomplished via a suboccipital approach, resulting in the angiographic cure of the fistula and progressive relief of the myelopathy. Fourteen reported cases of intracranial dural AVF draining intrathecally are reviewed. In most patients, authors encountered diagnostic difficulties similar to those noted in this case. Surgical and/or endovascular therapeutic methods have provided disappointing results, likely attributable to a prolonged course of spinal cord dysfunction. Pathophysiologically, a mechanism of venous congestion of the cord seems to be involved, as acknowledged by several magnetic resonance and angiographic studies. In patients who appear to have a clinical and myelographic picture of "vascular" myelopathy and who exhibit negative spinal angiography, a four-vessel cerebral angiography should be undertaken, aiming at the recognition of an intracranial AVF.