Arteriovenous malformations (AVMs) are defects in your vascular system. Your vascular system is your body's network of blood vessels. It includes your
Arteries, which carry oxygen-rich blood from your heart to your tissues and organs
Veins, which carry the blood and waste products back to your heart
Capillaries, which are tiny blood vessels that connect your small arteries to your small veins
An AVM is a snarled tangle of arteries and veins. They are connected to each other, with no capillaries. That interferes with the blood circulation in an organ.
AVMs can happen anywhere, but they are more common in the brain or spinal cord. Most people with brain or spinal cord AVMs have few, if any, major symptoms. Sometimes they can cause seizures or headaches.
AVMs are rare. The cause of AVMs is unknown, but they seem to develop during pregnancy or soon after birth. Doctors use imaging tests to detect them.
Medicines can help with the symptoms from AVMs. The greatest danger is hemorrhage. Treatment for AVMs can include surgery or focused radiation therapy. Because surgery can be risky, you and your doctor need to make a decision carefully.
NIH: National Institute of Neurological Disorders and Stroke
