Arteriovenous Malformation (AVM) - Causes, Symptoms, Complications, Diagnosis, and Treatment

What Is an Arteriovenous Malformation in the Brain?

Arteriovenous malformations or AVM, is a tangled cluster of arteries and veins (the two types of blood vessels). In almost all cases, it forms during the development of a child inside the uterus. An arteriovenous malformation may develop in any part of the body, including the brain. And there is a risk of rupture producing severe bleeding (hemorrhage). Now, this blood may raise the pressure inside the brain or obstruct normal blood flow, causing stroke or brain damage. With timely medical help, one can get rid of an arteriovenous malformation and avoid the above risks.

What Are the Causes of an Arteriovenous Malformation?

It basically involves two different kinds of blood vessels that should not be directly connected but get connected due to some developmental error. In the body, there are arteries which are the vessels that carry the blood from the heart to the rest of the body. Arteries are thick-walled and are designed to carry high-flow and high-pressure blood. Once the blood reaches wherever it is going in the body, the arteries split again and again until, ultimately, they form capillaries. These are tiny microscopic vessels that supply oxygen to all tissues of the body. After the oxygenation has taken place, it’s the veins that take the blood back to the heart from the brain. Veins are very thin-walled and are designed to carry low-pressure slow-flow blood. Hence, the arteries and veins are quite different in the way they are built, and ideally, they should not have direct communication between them.

In an arteriovenous malformation, the arteries and veins are directly connected by a tiny network of very small vessels during the development. This makes the high-pressure blood go straight from the arteries into the vein. There is built-up stress inside the vessels to the point where the weakest part of it ruptures and causes bleeding eventually. Individuals with a family history of arteriovenous malformation and those of the male gender are at a higher risk for this. If the arteriovenous malformation occurs at a very young age and it is of a very high flow, it can cause other troubles such as heart failure.

What Are the Symptoms of an Arteriovenous Malformation in the Brain?

In the majority of individuals, arteriovenous malformations stay symptom-free until they rupture to cause a bleed. A few of them show the following symptoms:

• Pain in the area of the head where an arteriovenous malformation is present.

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• Severe headaches.

• Seizures.

• Numbness, muscle weakness, or paralysis in one part of the body.

• Loss of body balance.

• Issues with speech or eyesight.

• Mental confusion and inability to comprehend things.

• In severe arteriovenous malformations involving major blood vessels of the brain, the fluid build-up makes the brain swell up and turn fatal.

What Are the Possible Complications Of an Arteriovenous Malformation Rupture?

Potentially life-threatening bleeding inside the brain is the most dangerous complication. The risk of hemorrhage varies depending on the area of the brain and the size of the arteries involved. A ruptured arteriovenous malformation can be one of the reasons leading to aneurysms (weakening and ballooning up of a blood vessel) and stroke. The large volume of leaked blood and the inflammatory fluid produced in response to bleeding fill up the spaces inside the brain and causes hydrocephalus (enlarged brain with fluid collection). It tends to compress the structures inside the brain against the walls of the skull and cause damage. Apart from that, it may deprive the other parts of the brain of getting adequate oxygen leading to tissue death.

How Is an Arteriovenous Malformation Diagnosed?

Bleeding from a ruptured arteriovenous malformation is a medical emergency. The affected individual requires urgent medical attention and a quick diagnosis. The doctor reviews the symptoms and medical history along with a physical examination. The following tests are conducted to confirm the diagnosis:

• Imaging studies like computed tomography (CT) or magnetic resonance imaging (MRI) to identify the exact location of the bleeding and possible damage to the brain.

• Cerebral angiography, where a long thin tube is inserted into an artery in the groin and guided up into the brain. A dye is injected into the artery, and with the help of an x-ray, one can visualize the site of arteriovenous malformation.

What Are the Ways of Treating an Arteriovenous Malformation?

The goal of treatment is to try to reduce the risk of bleeding and make it go away altogether. One may attempt the following strategies:

1. Surgical Removal - The doctor might suggest surgery if one has a high risk of bleeding. One can just remove the arteriovenous malformation surgically so that the risk of bleeding is eliminated. It involves the complete removal of the lesion. However, surgery will be feasible only if the arteriovenous malformation lies in an area that poses minimal risk of damaging the brain tissue.

2. Stereotactic Radiosurgery - Where radiation is used on the blood vessels till they begin to thicken up and begin to close off so that the arteriovenous malformation shrivels up. Eventually, it disappears over some time.

3. Endovascular Embolization - Where a very tiny wire is threaded up to the blood vessels inside the body, and one squirts different substances that can plug up the vessels from the inside. This may help to slow down or stop the flow of blood inside an arteriovenous malformation.

4. Review and Monitoring - Even after completing the treatment, one needs regular follow-ups with the doctor to check for recurrence. This includes periodic imaging studies and more.

Conclusion:

Sometimes, the safest thing to do in a very big arteriovenous malformation or one that is located in a very sensitive part of the brain is to just monitor it. Because the risk of treating the arteriovenous malformation might have more side effects and be more dangerous than leaving it alone, the doctor may recommend regular check-ups and imaging studies to assess the progress. With modern advancements improving surgical precision, removing arteriovenous malformations are more successful than before. Early medical intervention gives the best results in such a condition.