AV Malformations
An arteriovenous malformation (AVM) is an abnormal tangle of blood vessels connecting arteries and veins, which disrupts normal blood flow and oxygen circulation.
Arteries are responsible for taking oxygen-rich blood from the heart to the brain. Veins carry the oxygen-depleted blood back to the lungs and heart.
Symptoms of AVM vary based on where it's located. Often the first signs and symptoms appear after bleeding occurs, and can include:
Other possible signs and symptoms include:
Children and teens may have trouble with learning or behavior.
One type of AVM called a vein of Galen defect causes symptoms that appear at or shortly after birth. A vein of Galen defect is located deep inside the brain. Signs can include:
Seek medical attention if you have any of the signs and symptoms of an AVM, such as headaches, dizziness, vision problems, and changes in cognition or neurological function. Many AVMs are currently discovered by "accident," often after a CT scan or an MRI is obtained for reasons not directly related to the AVM.
AVMs are caused by development of abnormal direct connections between arteries and veins, but experts don't understand why this happens. Certain genetic changes may play a role, but most types are not usually inherited.
Rarely, having a family history of AVMs may increase your risk. But most types of AVMs are not inherited.
Certain hereditary conditions may increase your risk of AVM. These include hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu syndrome.
To diagnose an AVM, your doctor will review your symptoms and perform a physical examination.
He or she may listen for a sound called bruit. Bruit is a whooshing sound caused by very rapid blood flow through the arteries and veins of an AVM. It sounds like water rushing through a narrow pipe. Bruit may interfere with hearing or sleep or cause emotional distress.
Tests commonly used to help diagnose AVM include:
Treatment for AVM depends on where the abnormality is found, the symptoms that you have and your overall health. Sometimes, an AVM may be monitored with regular imaging tests to watch for changes or problems. Other AVMs require treatment. Determining whether or not an AVM needs treatment involves factors such as:
Medications can help manage symptoms such as seizures, headaches and back pain.
The main treatment for AVM is surgery. Surgery may be recommended if you're at a high risk of bleeding. The surgery may completely remove the AVM. This treatment is usually used when the AVM is small and located in an area where surgeons can remove the AVM with little risk of causing significant damage to the brain tissues.
Endovascular embolization is a type of surgery in which the surgeon threads a catheter through the arteries to the AVM. Then a substance is injected to create an artificial blood clot in the middle of the AVM to temporarily reduce the blood flow. This may also be done before another type of surgery to help reduce the risk of complications.
Sometimes stereotactic radiosurgery is used. This procedure is usually performed on small AVMs that have not ruptured. This uses intense, highly focused beams of radiation to damage the blood vessels and stop the blood supply to the AVM.
Deciding whether or not to treat an AVM is a decision that you and your doctor will discuss carefully together, weighing the possible benefits against the risks.
After treatment for an AVM, you may need regular follow-ups with your doctor. You may need more imaging tests to make sure that the AVM is completely resolved and that the malformation has not recurred. You may also need regular imaging tests and follow-up visits with your doctor if your AVM is being monitored.