A dural arteriovenous fistula (DAVF), is also named as dural arteriovenous malformation (DAVM), is an abnormal direct connection (fistula) between a meningeal artery and a meningeal vein or dural venous sinus. treatment: Treatment for dural arteriovenous fistulae (DAVF) depends on the blood vessels involved. Endovascular techniques, which are minimally invasive procedures that are performed through the blood vessels, have been developed to safely treat DAVFs. An approach, called embolization, reduces blood flow to the DAVF by obstructing surrounding blood vessels. During this procedure, the DAVF is filled with specially designed coils, glues or spheres that plug the vessels. Some fistulas can't be completely blocked with embolization and may require surgery to disconnect or close them. In some cases, doctors may try to close the fistula with what's called stereotactic radiosurgery or the Gamma Knife. pathophysiology : Vascular tumors:The most common vascular tumor is infantile hemangioma. It is seen shortly after birth, is more common in girls and in whites, and is congenital. These tumors are usually solitary but not infrequently they may be multiple and involve the liver, gastrointestinal (GI) tract, and central nervous system (CNS). They are characterized by three phases of growth, as follows : Proliferation, Involution,Involuted phase Vascular malformations: Generally, congenital vascular malformations are inborn errors in embryologic development. Woollard described the development of the vascular system in three stages, as follows: The first step is the condensation of undifferentiated cells into capillary blood spaces The next stage involves the formation of a retiform plexus in which blood flows from an arterial to a venous side; the channels in the retiform plexus combine and regress to form the vessels in the vascular system The last stage involves the development of axial arteries in the limb buds.