An arteriovenous malformation (AVM) is a congenital disorder (one present at birth) of blood vessels in the brain, brainstem, or spinal cord that is characterized by a complex, tangled web of abnormal arteries and veins connected by one or more fistulas (abnormal communications).
The AVM has no capillary bed of its own and the fistulas in the AVM permit high-speed, high-flow shunting of blood from the arterial to the venous side of the circulation. This shunting causes low blood pressure (hypotension) in the arterial vessels feeding the AVM and neighboring areas of the brain that they normally supply with blood.
AVMs typically cause problems before the age of 40. The most common symptoms of AVM include hemorrhaging (bleeding), seizures, headaches, and neurological problems such as paralysis or loss of speech, memory, or vision. The frequency of hemorrhage in various series ranges from 30-82%. AVM rupture accounts for 2% of all strokes.
There are three general forms of treatment for AVM:
Surgery, which is the best-known and longest-standing treatment for AVM. Surgery for an AVM involves identifying the margins of the malformation, ligating (tying off) or clipping the feeder arterial vessels, obliterating the draining veins, and removing or obliterating the nidus (the nest) of the AVM.
Endovascular occlusion, which involves closing off the vessels of the AVM by one of various nonsurgical means. Catheters can deliver agents to block the blood vessels that include permanent balloons, thrombosing (clogging) coils, sclerosing (hardening) drugs, and fast-acting embolization glue (embolization is often used before surgery).
Radiosurgery, which involves focusing multiple radiation beams on the AVM so as to injure and thrombose (clog) the AVM. The effect of radiosurgery takes weeks to months to become fully manifest. A real danger of radiosurgery is damage to neighboring nervous system tissue, normal brain (or spinal cord) tissue around the AVM. Therefore, radiosurgery is usually reserved for AVMs that are relatively small (less than 3 cm in diameter), situated so deep within important brain tissue that surgery is hazardous, or have so many feeder arteries that embolization is not feasible.
Most people (perhaps 80% or more) with AVMs never experience problems due to them. However, AVMs that hemorrhage can lead to serious neurological problems, and sometimes death.
- Arteritis, cranial
Arteritis, cranial: A serious disease characterized by inflammation of the walls of the blood vessels (vasculitis). The vessels affected are the arteries (hence the name “arteritis”). The age of affected patients is usually over 50 years of age. Cranial arteritis is also known as temporal arteritis and as giant cell arteritis. It can lead to […]
- Arteritis, giant cell
Arteritis, giant cell: A chronic vascular disease, most often involving the carotid artery system, that can lead to blindness and/or stroke, Giant cell arteritis (also called temporal arteritis) is detected by a biopsy of an artery, and is treated with high dose steroids.
- Arteritis, temporal
Arteritis, temporal: Also called giant cell arteritis or cranial arteritis, this is a serious disease characterized by inflammation of the walls of the blood vessels (vasculitis). The vessels affected by inflammation are the arteries (hence the name “arteritis”). The age of affected patients is usually over 50 years of age. Giant cell arteritis can lead […]
Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red. Arteries are […]
- Artery spasm, coronary
Artery spasm, coronary: A sudden constriction of a coronary artery that deprives the heart muscle of blood and oxygen. This can cause a type of sudden chest pain referred to as variant angina or Prinzmetal angina. Coronary artery spasm can be triggered by emotional stress, medicines, street drugs (particularly cocaine), and exposure to extreme cold. […]