Spinal arteriovenous fistula (SDAF) within the dura.
see also Dural arteriovenous fistula.
It is a connection between a radicular artery and a radicular vein, (there is no intervening nidus between a meningeal segmental artery and a radiculomedullary vein) resulting in venous hypertension and obstruction of the venous flow. Consequently, edema forms beneath the fistula and congestive ischaemia of the myelum develops.
They are the most common type of spinal arteriovenous malformation, especially in middle-aged men.
The annual incidence are 5-10 cases per million. The data on efficacy, recurrence rates and complications of endovascular treatment versus surgical treatment is limited.
The pathophysiology results in perimedullary venous congestion and in turn spinal cord congestion.
The craniocaudal extent of enlarged intrathecal veins draining SDAVF correlates with patient functional status, providing further insight into the pathophysiology of venous hypertensive myelopathy 1).