What is Arteriovenous Malformation?
An arteriovenous malformation (AVM) is an abnormal tangle of the blood vessels that connect the veins and arteries in your brain. An AVM can develop anywhere in the body, but it is more common in the brain and spine.
Symptoms of Arteriovenous Malformation
A brain arteriovenous malformation may remain asymptomatic until it ruptures, resulting in a brain haemorrhage, or bleeding in the brain. This may lead to other symptoms such as:
- Brain damage
- Hemorrhagic stroke
- Difficulty speaking
- Vision loss
- Headache or pain in one area of the head
- Confusion and inability to understand others
- Severe unsteadiness
Pregnant women may have more intense symptoms due to changes in blood volume and blood pressure.
The vein of Galen defect is a severe type of brain AVM that occurs soon or immediately after birth. The blood vessels involved are unable to pump blood, which leads to fluid accumulation in the brain and swelling. The symptoms include swollen veins visible on the scalp, seizures, and congestive heart failure.
Causes of Arteriovenous Malformation
Brain AVM is caused during fetal development due to faulty flow of blood in the arteries and veins that supply the brain.
The arteries supply oxygen-rich blood from the heart to your brain while the veins carry de-oxygenated blood back to the lungs and heart. In a brain AVM, this flow of blood is disrupted.
Risk factors for Arteriovenous Malformation
The risk factors for brain AVM include:
- Having a family history of AVMs
- Gender, as AVMs are more common in males
Diagnosis of Arteriovenous Malformation
A brain AVM is diagnosed through review of your symptoms and a physical examination. In addition, you may need to undergo the following tests:
- Brain MRI scan
- CT scan
- Cerebral angiography, also called cerebral arteriography: This test involves injecting a dye into the blood vessels of your brain through a thin tube called a catheter and observing the blood vessels under X-rays. This is known as a brain angiogram and provides an accurate location of the arteries and veins.
Treatment of Arteriovenous Malformation
The choice of AVM treatment depends on your age, health, and the location and size of the abnormal blood vessels.
The primary goal of treatment is to prevent brain haemorrhage and minimize related symptoms such as seizures and other neurological complications. The various treatment options include:
- Medications to control headaches and other related symptoms
- Stereotactic Radiosurgery: This technique uses a focused radiation beam to target the blood vessels supplying the AVM. This causes them to scar and clot, thereby shrinking the AVM.
- Surgery: The different procedures include:
- Endovascular Embolization: In this procedure, a thin catheter is inserted into a leg artery and with the help of live X-ray imaging, passed through the blood vessels up to your brain. The catheter is positioned in one of the arteries supplying the AVM. Then, an embolizing agent such as a glue-like substance or small particle is injected to block the artery supplying the AVM.
- Surgical Removal of the AVM: In this procedure, an incision is made into the scalp and a small section of your skull is temporarily removed. With the help of a high-powered microscope and surgical instruments, the AVM is sealed and removed from the surrounding brain tissues. Then the skull bone is replaced and the incision in your scalp is closed.