Arterivenous Malformation (AVM) of Brain

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What is an AVM Brain?

An AVM or arteriovenous malformation of the brain is the entangling of the abnormal blood vessels that connect the veins and arteries of the brain. The chief role of arteries is to carry oxygenated blood from the heart to the brain. Contrary to this, the role of veins is to carry deoxygenated blood back to the heart as well as the lungs. An AVM of the brain disrupts the functioning of this process.

What causes Brain AVM?

The primary cause of AVM is still unclear. Some people have brain AVM by birth while some others develop the same later. A notable point is the passing down of this malformation amongst families, genetically.

Occurrence rate of AVMs

Brain AVMs occur very rarely and their occurrence rate is around 1% of the population. However, you might observe male predilection for AVM of the brain.

Where AVMs occur

Although an AVM may develop anywhere within the body, the most common sites are the brain and spine. However, brain AVM is rare and affects only a small chunk of the human population.

Symptoms of Brain AVMs

You may not notice any symptoms of brain AVM till it ruptures. Rupturing of AVM of the brain may result in bleeding within the brain which is termed hemorrhage. A majority of the patients with brain AVM experience hemorrhage as the first sign. Other symptoms of brain AVM include:

  • Constant pain in any specific area of the head
  • Problems with speech
  • Progressive loss of neurological function
  • Numbness or paralysis
  • Dizziness
  • A problem in understanding language
  • Nausea and vomiting
  • A problem in performing certain tasks that require planning
  • Back pain
  • Loss of coordination
  • Seizures
  • Muscle weakness in a specific part of the body
  • Loss of consciousness
  • Weak lower limbs
  • Confusion
  • Vision loss
  • Serious unsteadiness
  • Hallucinations
  • Inability to understand what others are saying
  • Loss of control on eye movements
  • Tingling sensations

Causes of bleeding AVM

The abnormal blood vessels in brain AVM are weak. Hence, they direct blood in a direction against the tissues of the brain. As there is dilation of the abnormal blood vessels with time, they tend to burst. A brain AVM ruptures and bleeds because of the blood flow in a high pressure coming from the arteries.

Chances of AVM bleeding

A brain AVM generally develops between the age of 10 years to 40 years. On average, the chances of bleeding of brain AVM is between 1% to 3% per year. If it bleeds for the first time, the patients are at risk of recurrent bleeding within a short period. Teenagers and the young age group people are at a high risk of experiencing recurrent bleeding. 

When to visit the doctor?

If you notice any signs or symptoms of brain AVM, you must visit the doctor immediately. These cases require emergency medical attention otherwise they may bleed profusely & prove to be fatal.

Stages of brain AVM

  1. Stage 1 of Quiescence: AVM brain malformation is quiet in this stage. The skin surface above the AVM is red and feels a little warm.
  2. Stage 2 of Expansion: The malformation increases in size to become larger and it is easy to feel the pulse within the malformation.
  3. Stage 3 of Destruction: The brain AVM begins to bleed and pain.
  4. Stage 4 of Decompensation: This stage may turn out to be fatal as heart failure occurs in most cases.

Can AVM bleeding prove fatal?

Around 10% to 15% of deaths occur after each AVM brain bleeding. Some patients experience permanent brain damage that accounts for around 30% of the total cases. Every bleed contributes to the damage of normal tissues within the brain that may alter the normal brain functions temporarily or permanently. 

Types of Brain AVM

There are 5 different types of brain AVM. These types are listed as under:

  1. True AVM: This is the most common type of malformation in which the abnormal blood vessels tangle. However, there is no interfering normal tissue of the brain.
  2. Venous malformation: This malformation involves only the abnormal veins.
  3. Dural fistula: Dura mater, the covering of the brain, often gets involved in an abnormal connection with the blood vessels. This results in the formation of a dural fistula. There are three types of dural fistulas namely transverse- sigmoid sinus dural fistula, dural carotid-cavernous sinus fistula, and sagittal sinus-scalp dural fistula.
  4. Cryptic or occult AVM or cavernous malformations: This type of vascular brain malformation doesn’t draw away large quantities of blood. Such malformations may cause seizures and bleed.
  5. Hemangioma: Abnormal blood vessels at the brain or skin surface are termed hemangioma.

Risk factors of Brain AVM

Males are at a higher risk of developing brain AVM. Apart from this, families with a history of brain AVM have generic passing down of the same.

Complications of Brain AVM

The complications of brain AVM include stroke, speech or movement problems, low quality of life, developmental delays (in children), and numbness in specific parts of the body. Other complications associated may be:

  • Weaker blood vessels: An AVM brain exerts pressure on the weaker blood vessels. This may result in an aneurysm or a bulge in the walls of the blood vessels that may rupture later.
  • Hemorrhage: AVM causes the walls of the affected veins and arteries to weaken which results in bleeding within the brain or hemorrhage. While hemorrhage goes undetected in some people, some others experience episodes that may be life-threatening.
  • Brain damage: In many cases, AVM increases in size to constrict some portions of the brain. Because of this, protective fluids are unable to circulate freely and instead collect at a place. This may cause brain tissue to get pushed against the skull resulting in brain damage.
  • Reduced oxygen supply: When brain AVM develops, blood circulates directly to the veins & the arteries. Because of this, surrounding tissues are unable to absorb oxygen from the blood, and these tissues weaken or die.

How Brain AVMs are diagnosed

Your doctor will review all your symptoms and perform a thorough examination. For forming a diagnosis, he or she might ask you to undergo certain tests. These tests are usually performed by neuroradiologists. They are professionally trained to conduct imaging tests for finding the cause and the diagnosis of the condition.

Tests

  • CT scan: A Computerized Tomography scan creates a cross-sectional radiographic image of the brain through an x-ray series. Sometimes, doctors perform angiograms which involves injecting a dye. This dye is injected into the veins through a tube so that minute details can be seen.
  • Cerebral arteriography: Also called cerebral angiography, it helps to accurately diagnose AVM. It reveals not only the characteristics of arteries that supply AVM and the draining veins but also the exact location. These details are essential for the diagnosis and treatment of the condition. Your doctor will insert a tube called a catheter in the artery of the groin region. He or she will use x-ray imaging to thread it to the brain. Injecting the dye will make the blood vessels clear enough to be seen in the x-ray imaging.
  • MRI: Magnetic Resonance Imaging uses radio waves and magnets to obtain precise brain images. This test will provide you with the exact location of AVM within the brain along with any other bleeding spot. Alternatively, your doctor might perform Magnetic Resonance Angiogram using the dye.

Treatment of Aterivenous Malformations (AVMs) of Brain

There are ample treatment options for this malformation. The primary goal is to avoid hemorrhage but it is vital to consider the neurological complications. Your health, gender, age, location, and size of the blood vessels are some critical factors that help in determining the right treatment option.

Stereotactic radiosurgery

This type of treatment involves radiation for the destruction of the brain AVM. To simply put, this isn’t surgery but involves targeting of AVM by the radiation beams. This damages the abnormal blood vessels leaving a scar. The scarred blood vessels clot off within a few years of the treatment. If you have a small AVM that can’t be removed with conventional surgery then your doctor might suggest SRS. People having hemorrhages that may turn fatal also undergo SRS treatment

Endovascular Embolization

It is also called interventional neuroradiology. Your doctor will insert a catheter tube into the artery of your leg and thread it with the brain blood vessels. The catheter is placed in one of the arteries that feed AVM followed by injecting of the embolizing agent. This will block the blood flow to the feeding artery. This is a minimally invasive procedure and is usually done before any surgery. It reduces the chances of AVM bleeding and reduces its size. Endovascular embolization also decreases the chances of stroke-type symptoms.

Surgical removal or resection

If the AVM is bleeding or is located in an easily accessible area of the brain, resection via conventional brain surgery is a preferable treatment option. Your doctor will temporarily remove a portion of your skull to perform resection. AVM can be easily removed with the help of special clips followed by reattachment of the skull bone. Suturing of the incision follows this process to close the scalp region.

Medical therapy

If you aren’t experiencing any symptoms of AVM or the AVM is located in an inaccessible area, you will undergo conservative management. Your doctor will ask you to avoid excess workouts and exercise. Also, you will have to discontinue the intake of blood thinners or anticoagulants like warfarin.

Specialists for brain AVM treatment

A brain AVM treatment is performed by specialists who hold a specialization degree in such cases. They may be:

  • A neurosurgeon or radiation therapist who performs stereotactic radiosurgery treatment.
  • A stroke neurologist who is proficient in the medical management of such malformations. They can also diagnose easily and perform imaging of the head, neck, and brain region.
  • The vascular neurosurgeon can perform surgical removal of AVM of the brain.
  • An endovascular neurosurgeon or interventional neuroradiologist who excels in endovascular therapy.

Prevention and prognosis

Most commonly, an AVM occurs by birth or sometime later after the birth of the child. Prevention is difficult as the causes are unknown for a majority of the cases. However, the best thing would be to seek medical attention as soon as you notice the first symptom for a better prognosis. Timely medical treatment always helps in easy management and provides a better quality of life. People who get to know about AVM through bleeding usually die. Some others experience seizures and problems with the nervous system. Many people with undetected AVM till their 50s or 60s experience no symptoms and are stable.

Follow up

You need to visit your doctor regularly for follow-ups after getting surgically operated on for brain AVM. Your doctor might advise you imaging tests again to ensure there is no recurrence and the malformation has resolved completely.

FAQs on Brain AVM

Brain AVM is curable within 2-3 years of treatment. Radiosurgery is often a treatment choice for AVMs that are small in size but in exceptional cases, one may opt for it even for the removal of large AVMs.

One in 2000 people develop brain AVM. A majority of the people live normally with it but they have a risk of bleeding AVM at some time. Sometimes, they may also suffer a stroke due to AVM.

In most cases, AVMs do not rupture. However, there may be recurrent bleeding after it ruptures once.

Most of the asymptomatic AVM cases have a history of bleeding. Due to increased stress, you may have high BP. This may cause the AVM to bleed as the blood will flow at a fast rate and the vessel walls will be weak.

The most important thing to keep in mind is that you must avoid anything that elevates the blood pressure. If you perform a high workout or a strenuous activity, your blood pressure may rise. This will result in strain on your malformation and there are high chances of AVM rupture or bleeding.

 

AVM is a collection of abnormal blood vessels that restrict blood circulation to the brain. It may sometimes be accompanied by vascular tumors that are surgically removed.

Although there are no cases of passing down of AVM in families, a mere 5% of cases are due to autosomal dominance. However, the causes of AVM are still unknown in a majority of the cases as it is present by birth.

A Grade 4 or Grade 5 AVM is considered a large AVM as it is big and deep within the brain. In most cases, a large AVM is considered to be a risky malformation to be operated upon.

 

No, AVM hasn’t been identified as a condition of disability but severe complications of its rupture may result in the disability of the person.

 

No, a brain AVM does not cause any kind of personality changes. However, a patient may experience emotional changes due to the stress of the same.

The warning signs of a brain aneurysm are seizures, headache, nausea, vomiting, loss of consciousness, stiff neck, drooping eyelids, and blur vision.

 

The symptoms of a brain aneurysm headache are pulsing sensation and throbbing pain. This may last for a couple of hours to a few days and it may be debilitating. The patient might also experience sensitivity to extreme sound and sunlight.

Medical therapy can help you get relief from the symptoms of AVM like headache and pain. You can perform routine activities only after several weeks following the surgery. Most patients require around 4 to 6 months to completely recover from the condition.

There will be a headache suddenly that is severe enough to disturb the patient. The patient will experience headaches in only a specific region of the head with a ringing sound in the ear.

 

A Cavernoma or a cavernous angioma or a cavernous malformation is one of the types of AVM of the brain. It also contains a collection of weakened blood vessels that block the blood flow.

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