Also called: AVM

Arteriovenous malformations (AVMs) are defects in your circulatory system. The circulatory system includes the arteries, veins and capillaries that carry blood to and from the heart. An AVM is a snarled tangle of arteries and veins. It interferes with the blood circulation in an organ. AVMs can happen anywhere, but the ones located in the brain or spinal cord can have effects such as seizures or headaches. However, most people with brain and spinal cord AVMs experience few, if any, significant symptoms. The cause of AVMs is unknown, though they seem to develop during pregnancy or soon after birth. The greatest danger of an AVM is hemorrhage. Prevention can include surgery or focused irradiation therapy.