What is this disease in which blood vessels are abnormally tangled? (Arteriovenous Malformation - AVM) Let's talk!

Have you ever heard that the blood vessels inside our bodies can sometimes get tangled up in strange ways, like a ball of thread? This may sound a bit strange, right? But, it can actually happen, and it can be a bit dangerous at times. Today we are going to talk about a condition called Arteriovenous Malformation , or AVM . Simply put, this is a defect in the system of veins that transport blood in our body.

What is an arteriovenous malformation (AVM)? Let's understand it simply.

Imagine that we have a network of blood vessels throughout our bodies. There are two main types of these vessels: Arteries and Veins . Arteries are like highways, carrying clean, oxygenated blood from the heart to all parts of the body, especially the brain. Veins are like smaller arteries that carry used, deoxygenated blood back to the heart.

Normally, these highways (arteries) end in a network of very small, thin veins. We call these capillaries . It's like a big road that branches off into small side roads when it reaches a village. It's through these capillaries that the oxygen and nutrients in the blood reach our cells, and the waste products from the cells get into the blood. Then this blood goes back to the heart through veins called veins.

Now, what happens in a person with an AVM is that the capillary bridge that should be between the artery and the vein is missing. Then, the blood from the arteries, which is coming from high pressure, suddenly connects to the veins, which are used to low pressure. Imagine a large water pipe suddenly connecting to a small, weak-walled pipe. This causes the veins to have an unbearable pressure. This is seen as a tangled ball of blood vessels, like a bird's nest. Because of this abnormal connection, there is a high chance of the blood vessels bursting (Rupture) and bleeding into the brain (Bleeding into the brain) .

Are there different types of AVMs? Where do they form?

Yes, we can mainly talk about two types of AVM:

1. Brain AVMs: These are the most common. They can develop anywhere inside the brain, on the surface of the brain, in the brainstem , or along the spinal cord . These are a bit dangerous because the brain is a very sensitive place.

2. Peripheral AVMs: These can occur anywhere in the body's 100,000 miles of blood vessels. For example, they can develop in the face, arms, legs, as well as in internal organs like the heart, liver, and lungs.

How common is this condition called AVM?

AVM is actually a very rare condition. It is said that only one in a hundred thousand people can have it. Anyone can have it at birth. However, doctors find it most often in people between the ages of 20 and 40. Symptoms are most likely to appear between the ages of 30 and 50.

What are the symptoms of an AVM?

Here's the important thing. Some people may have an AVM and not show any symptoms. About 15% of people with an AVM will not have any symptoms. Most of the time, you only find out you have an AVM after it ruptures, which means it bleeds.

However, if symptoms do occur, they may be like this:

• Seizures, either unconscious or conscious. This can happen suddenly.
• Frequent headaches. Sometimes this can be severe.
• Muscle weakness or complete paralysis.
• Nausea and vomiting.
• Numbness or tingling sensation in some parts of the body.
• Dizziness.
• Difficulty walking, difficulty speaking, memory loss, difficulty thinking, loss of balance, or vision impairment.
• Conditions such as mental confusion, hallucinations, or dementia.
• Back pain. This can come on suddenly and be severe. It can also cause a feeling of numbness from the hips to the legs and toes.
• Shortness of breath during exertion (this can happen if there is an AVM in the lungs)
• Coughing up blood (this is also a symptom of lung AVMs)
• Abdominal pain.
• Lumps appear on the arms, legs, or trunk.
• Pain and swelling.

Important: About 50% of people with a brain AVM will experience a bleeding in the brain as their first symptom. This can lead to stroke and brain damage.

Why do these AVMs form? What is the cause?

In fact, scientists still don't know exactly why AVMs develop. It is widely believed that they are congenital . This means that these blood vessel tangles form during fetal development, in the mother's womb. Very rarely, they can be passed down from generation to generation, which means they can be hereditary .

What effect does an AVM have on our body?

There are three main ways in which an AVM can cause damage:

1. Bleeding: As I mentioned earlier, when the high blood pressure from the arteries passes through the AVM, the walls of the veins may be weak and unable to withstand the pressure. Then the veins burst and start bleeding. When this blood gets into the surrounding tissues, it can cause permanent damage . If there is a large amount of bleeding , it can even cause death.

2. Pressing on body parts: This abnormal connection causes more blood to pool in the veins. The veins then become enlarged and can press on surrounding tissues, such as the brain. This reduces the amount of oxygen that reaches those parts and reduces the ability of the lymphatic system to remove waste products.

3. Depleting tissues of needed oxygen: Because there is no capillary bridge between the arteries and veins, the tissues in the area of ​​the AVM do not receive enough oxygen and nutrients. Then the tissues and nerve cells in that area can begin to die.

What are the possible complications of AVM?

AVMs, especially in the brain, can cause serious complications such as:

• Brain bleed / Stroke : This is the biggest risk of an AVM. If an AVM bursts inside the brain, it can cause paralysis, brain damage, or seizures. The AVM can also push on and damage parts of the brain or spinal cord.
• Seizures: A condition characterized by loss of consciousness and uncontrollable jerking of limbs due to sudden electrical activity in the brain.
• Aneurysm: A weakened wall of a blood vessel that is connected to or around an AVM and bulges out like a balloon. These are caused by weak blood vessel walls. This condition is seen in about 50% of AVMs in the brain and spinal cord. These increase the risk of the AVM rupturing.
• Brain damage: This can affect things like thinking ability, memory, and understanding speech.
• Coma and death: Especially if there is a large bleed inside the brain.

How do you find out if you have an AVM?

If you have symptoms, your doctor will first ask you about them and do a physical exam. Sometimes, when a stethoscope is placed over an AVM, a bruit (sound of blood rushing through the blood vessel) can be heard.

In addition, imaging tests such as:

• MRI (Magnetic Resonance Imaging) Scan: A test that uses a magnetic field and radio waves.
• CT (Computed Tomography) Scan: Uses X-rays to take cross-sectional images of the body.
• Catheter Angiography: In this procedure, a doctor inserts a small tube (catheter) through an artery in your arm or groin and guides it to where the AVM is thought to be. A special dye is then injected and X-rays are taken to obtain detailed images of the blood vessels.

If an AVM is suspected in the brain, specific tests such as:

• Cerebral MRI Angiography (Cerebral MRA): Uses MRI technology to obtain detailed images of the blood vessels in and around the brain.
• CT angiography (CTA): CT technology produces detailed images of blood vessels.
• Transcranial Doppler ultrasound: Uses sound waves to measure the speed of blood flow through the brain.

Because many AVMs have no symptoms, they are sometimes discovered during a scan done for another reason (such as an injury, vision problems, or headaches), or after symptoms develop due to bleeding.

How is an AVM treated?

The treatment of an AVM depends on several factors, including:

• The type of AVM, how big it is, where it is located, and the nature of the arteries and veins involved.
• The risk of the AVM rupturing.
• Your symptoms.
• your age.
• Your overall health.

The main goal of treatment is to reduce the risk of bleeding from the AVM, or to completely cure it. There are several treatment options. These include open surgery , catheter-based artery blocking (Embolization) , and/or focused radiation (Radiosurgery) to the AVM . Each treatment option has its own benefits and risks. These vary depending on your health and the type of AVM.

Generally speaking, treating an AVM as soon as possible is the best way to avoid serious complications.

Everyone's AVM is different. There is no set treatment plan that can tell you exactly what to do. Your medical team will talk to you and your family to decide on the best treatment for your situation.

Sometimes the AVM is in a location where surgery or other treatment is more risky than doing nothing. In this case, your medical team will monitor your AVM closely with periodic scans. If the AVM shows any changes, such as signs of increased bleeding, treatment may be considered at that time.

Medications

Medications can be given to control some symptoms:

• Anti-seizure medications.
• Pain relievers for headaches and backaches.
• Blood pressure medications.

Treatment methods (Procedures)

Doctors may try one or more of these methods:

1. Surgery to remove the AVM: In this, a small incision is made near the AVM, the surrounding arteries and veins are sealed to prevent bleeding, and the AVM is removed. Then, blood flow is diverted to the normal blood vessels. This is the only way to completely cure the AVM. After surgery, a brain scan is done to see if the AVM has been completely removed. You may have to stay in the hospital for a few days and undergo a short rehabilitation period.

2. Embolization: In this procedure, a doctor inserts a catheter into an artery in your groin or arm and guides it to the AVM. Once there, a glue-like substance, coils, or other material is released into the AVM. This reduces or completely stops the bleeding through the AVM. This procedure is most often used if the AVM is large and bleeding heavily. Then, if surgery is performed later, the AVM can be easily removed, reducing the risk of bleeding. Although surgery is not performed immediately, this procedure can reduce the risk of bleeding.

3. Gamma Knife® radiosurgery: In this, highly focused beams of radiation are directed at the AVM. Over a period of several years, the AVM gradually shrinks, scars, dissolves, or becomes small enough to be easily removed by surgery. Periodic scans are required to check whether the AVM is shrinking.

Complications of treatment

AVM treatment may cause complications or side effects such as:

• Bleeding.
• Headache.
• Swelling.
• Damage to surrounding tissues.
• Numbness on one side of the body.
• Effects on speech, hearing, or vision.
• Results may be incomplete, may not last long, or may take months to fully appear.
• Severe complications that can be disabling or fatal.

Can AVM formation be prevented?

No. Since AVMs are believed to be congenital, they cannot be prevented from forming. However, if you experience any of the symptoms mentioned in this article, see a doctor immediately. It is best to respond to symptoms as soon as they appear.

What can you expect if you have an AVM?

Everyone's AVM is different. If you have surgery and the AVM is successfully removed, you will be completely cured of this condition.

The results of other treatments are also very good, but it depends on several factors:

• Where the AVM is located.
• The size of the AVM.
• Type of AVM.
• Your age and general health.

Your medical team can best explain to you about your AVM and the possible outcomes.

Important: If you have an AVM and you don't get treatment, there is a 2-4% risk per year that it will bleed. An AVM that has ruptured previously has a 17% chance per year of re-rupturing.

When should I see my doctor?

Some people may have an AVM more than once (recur). See your doctor if you develop new symptoms. After treatment, you should see your doctor every three months for the first year. After the first year, you should see your doctor once a year.

When should I go to the Emergency Department (ETU) ?

Seek medical help immediately if you experience any of these symptoms:

• A sudden, severe headache ("the worst I've ever had in my life").
• Convulsions.
• Numbness in the arms or legs.
• Problems with vision, balance, memory, or attention.

These are signs of a life-threatening emergency. This could be a brain hemorrhage.

What questions should I ask my doctor?

Some questions you can ask your doctor:

• Where is my AVM located on my body?
• What treatment method is best for me?
• If I don't have surgery right away, how often will I need to be monitored?

Is AVM dangerous?

Yes, it can. The biggest danger is bleeding (hemorrhage). If you suddenly have a severe headache ("the worst you've ever had in your life"), call 119 immediately. It could be a ruptured AVM in the brain. An unruptured AVM has a 2-4% risk of bleeding per year. A previously ruptured AVM has a 17% chance of re-rupturing per year.

Do all AVMs eventually bleed?

No. Some AVMs never bleed, and may not cause any symptoms or health problems throughout life. Some AVMs are discovered during a scan done for another reason or at an autopsy.

AVMs can cause other health problems besides bleeding. Some AVMs that grow large can compress an area of ​​tissue, damaging that tissue, nerve cells, and other cells. If they are large and in a critical location, the lack of capillaries between the arteries and veins prevents the tissue in that area from receiving oxygen, nutrients, and waste products. This can cause tissue death.

Can AVM be fatal?

Yes, it can. How dangerous and severe an AVM is depends on its size and location. If an AVM ruptures and causes a large amount of bleeding inside the brain, it can be fatal. However, some people with AVMs never experience any symptoms or health problems.

Can you tell where the AVM is from where I feel the pain in my head?

Not necessarily. It could be, but most of the time the headache is not specific to the location of the AVM.

Is the risk higher if a pregnant woman has an AVM?

For some people, AVM symptoms may suddenly appear or worsen due to changes during pregnancy . The increased blood volume and blood pressure during pregnancy can increase the risk of bleeding from an AVM.

Do AVMs affect young children?

AVMs can cause minor behavioral changes or learning disabilities in children. These changes may occur before more obvious symptoms appear until the child is a little older (if symptoms develop).

Do brain hemorrhages from AVMs always cause brain damage?

No. Some very small brain bleeds, called microbleeds , cause limited damage and few symptoms. However, if many microbleeds occur over time, they can increase the risk of dementia and interfere with thinking processes.

What is the difference between AVM, Aneurysm, Hemangioma, Cavernous malformation, and Fistula?

• An aneurysm is a weakened, balloon-like bulge in an artery. It most often forms where two arteries divide. An aneurysm can also develop as a complication of an AVM.
• Hemangiomas are vascular malformations that can be seen on the skin. They are not dangerous and do not require treatment.
• Cavernous malformation is also a type of vascular lesion. Unlike AVMs, these are blood vessels that are leaking, often with clots. They can bleed, but they don't bleed as badly as AVMs, and they often don't cause symptoms.
• Fistula is a general term for an abnormal connection between blood vessels. Arteriovenous fistulas can form in the tissues that cover the brain and spinal cord. AVMs form within the brain tissue. Fistulas are more commonly associated with head trauma or infection than AVMs.

Although arteriovenous malformation (AVM) is a serious medical condition, current treatments are very effective. Your medical team will discuss the details of your AVM – its size, location – and other factors with you to determine the best treatment options for you. Don’t be afraid to ask questions if something is unclear. Understanding your options can help you make the right decisions.

The most important things we need to remember (Take-Home Message)

Okay, so let's summarize some things to remember about the AVM we talked about:

• An AVM is an abnormal tangle of blood vessels that connects arteries and veins directly, without capillaries, like a bird's nest.
• These may be congenital , the exact cause is not known.
• Symptoms do not occur in everyone, but symptoms such as headaches, seizures, and loss of consciousness may occur.
• The biggest risk is bleeding, especially if it occurs inside the brain. This can lead to stroke.
• It can be detected through tests such as MRI, CT scan, and angiography .
• Treatment options include surgery, embolization, and radiosurgery . Your doctor will decide what is best for you.
• If you experience a sudden, severe headache, seizure, or loss of consciousness, go to the hospital immediately.
• Although this is a rare condition, it is very important to be aware.

If you or someone you know has any of these symptoms, please seek medical advice. The most important thing is to not panic, get the right information, and take the necessary steps.

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