Brain Arteriovenous Malformation

What is Brain AVM?

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What are Arteriovenous Malformations (AVMs)?

Typically arteries carry blood with oxygen from the heart to the brain and veins carry blood with less oxygen away from the brain and back to the heart.

An arteriovenous malformation, also known as AVM, involves a tangled nest of blood vessels that bypasses normal brain tissue and directly diverts high pressure blood from the arteries to the veins. 

Figure 1
Arterial phase cerebral angiogram demonstrating a large left parietal AVM. Nidus or the center of the AVM is indicated along with feeding arteries and draining vein.

What is the risk if you have a brain AVM?

Since the tangled nest of AVM vessels are often thin-walled and fragile, the AVM can spontaneously bleed into the brain, which is a life threatening emergency. This risk of AVM bleeding is 2-4% per year. This risk is cumulative over a patient’s lifetime. Therefore the lifetime risk of AVM bleeding is higher in younger patients with a brain AVM. 

What are the Symptoms of a brain AVMs?

Symptoms will vary depending on the severity and location of the AVM. A brain AVM that has bled will have severe, sudden onset symptoms such as headache, vomiting, weakness or even coma. Most brain AVMs that have not bled will cause very few, if any symptoms, or may share symptoms with other medical conditions. In fact, many patients will have no symptoms at all.

Symptoms of unruptured brain AVMs are infrequent, but may include:

  • Headaches
  • Seizures
  • Muscle weakness or paralysis
  • Problems with balance
  • Unusual tingling or numbness
  • Dizziness
  • Difficulty controlling eye movement
  • Mental confusion or dementia

How Common are Brain AVMs and Why Do They Occur?

Brain AVMs are rare and affect less than 1% of the population, or about 10 per 100,000 people.

An estimated 300,000 Americans are affected by arteriovenous malformations of the brain and spinal cord (neurological AVMs), but only about 12% of this population will ever have symptoms

AVMs are equally common among both men and women or all races and ethnicities. They are believed to be congenital, or existing at or sometime after birth, but they can enlarge over time and cause symptoms at any age.

Are There Different Types of AVMs?

There are 5 types of diagnosed AVMs.
They are: 

  • True arteriovenous malformation: This is the most common type of brain vascular malformation. It consists of a tangling of abnormal vessels that connect arteries and veins with no normal intervening brain tissue. 
  • Cavernous malformations/ cavernoma: This is a low flow vascular malformation in the brain that does not actively divert large amounts of blood. This condition may cause bleeding and produce seizures. 
  • Venous malformation: This condition only involves an abnormality of the veins that is typically congenital and has a very low risk of bleeding. 
  • Dural arteriovenous fistula: This consists of an abnormal connection between blood vessels that involve only the surface covering of the brain. 

How Are AVMs Diagnosed?

Most AVMs are detected through either a CT scan or an MRI scan. An angiogram is usually performed to better identify the type of AVM, its size and a detailed analysis of the AVM structure.

What happens if there is bleeding from a brain AVM?

An AVM rupture is a serious event and is often heralded by severe, sudden onset headache, nausea, vomiting, paralysis, loss of consciousness and other neurological symptoms. These patients are often brought to their nearest emergency room. Diagnosis of intra-cerebral hemorrhage is established with head CT scan and often the pattern of bleeding suggests the presence of an AVM.

Further studies including CT angiography, MR and MR angiography support the diagnosis and provide localizing anatomical information. A definitive understanding of the anatomy of AVM is obtained from cerebral angiography.

What are the Treatment Options for AVMs?

There are different medical treatments for an AVM. The following treatment options include:

  • Medical therapy: Conservative treatments such as controlling blood pressure, seizures and observing for any new symptoms over time.
  • Surgical removal of the AVM: Surgery may be recommended if an AVM has bled or if it is in an area that can be easily accessed. 
  • Stereotactic radiosurgery: If an AVM is not too large, but is in an area that is difficult to reach via regular surgery, it may be treated with stereotactic radiosurgery. This treatment does not involve any incisions. The procedure involves performing a cerebral angiogram to localize the AVM. Then, focused-beam high energy sources are concentrated on the AVM. The AVM may be gone in 2-3 years after radiosurgery.
  • AVM embolization: A minimally invasive procedure in which small catheters are used to fill portions of the AVM with “glue”, or liquid embolic agent. The AVM is shrunken gradually by embolizing and blocking the feeding arteries. Embolization can be done as part of a multistage treatment plan that later involves surgery or radiation treatment.

If you have been diagnosed with a brain Arteriovenous Malformation, it is important to speak with a surgeon who has experience treating patients with these conditions. The skilled and compassionate team at New Jersey Brain and Spine have been caring for patients for more than 25 years.

Contact us today to learn more about our personalized treatment options, or to schedule an appointment or second opinion.

Figure 2
Lateral late arterial phase cerebral angiogram showing a small posterior parietal AVM with indicated arterial supply, nidus and draining vein.

Figure 3
Same patient as above with before and after images superimposed showing embolic material filling the nidus and draining vein.

Figure 4
Lateral cerebral angiogram showing small AVM encircled by white line. Right: One year post gamma knife angiogram showing absence of filling (white line indicates estimated location of target) proving obliteration of AVM.

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