Brain Arteriovenous Malformation (Spotlight Series #1)

By Vincent Huang

We all know that our circulatory systems play a vital role in our brain’s health—a few seconds without circulation, and our brain tissue starts to die! But what if our circulatory worked against our brain, rather than for it?

A Brain Arteriovenous Malformation (AVM) is a tangle of abnormal blood vessels connecting arteries and veins in the brain. The arteries are responsible for taking oxygen and nutrient-rich blood from the heart to the brain, and veins carry the oxygen and nutrient-depleted blood back to the heart and lungs for. Between arteries and veins are capillary beds, which diffuse these vital nutrients into our body tissues, providing them with the materials they need to maintain proper function. A brain AVM disrupts this vital process by forgoing the capillary bed, creating a circulatory short-circuit.

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[1] A Brain AVM.

The AVM brings blood to the AVM and doesn’t deliver any nutrients or oxygen due to its lack of a capillary bed, leading to a shortage of oxygen and nutrients in a particular part of the brain. The AVM also has a risk of bursting that compounds over the years due to the quick rush of blood, which is usually slowed by Capillary beds between the artery and the vein. This weakens the walls of the AVM, increasing its risk of bursting and causing a brain hemorrhage. This gives AVMs a higher mortality rate than a stroke, with an 86.8% chance of bursting by the age of 50. It is the leading cause of nontraumatic intracerebral hemorrhage in people less than 35 years old and grows as the victim grows. As a consequence of the AVM’s elusive nature, a vast majority of those affected by it don’t know that they have it until it ruptures, killing 25% and leaving another 25% with permanent disabilities as a result of the destruction of brain tissue.

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[2] Risking of Bleeding from an AVM (source link: University of Toronto).

The cause of AVMs is not clear. Most AVMs are congenital, but they can occasionally form later in life. Some victims of brain AVMs experience symptoms, such as seizures or headaches, but most people don’t experience any signs until rupture. AVMs are often found after a scan for other health issues or after the AVM ruptures and bleeds within the brain (hemorrhage).

Once detected, a brain AVM can often be treated or removed to prevent future problems, such as brain hemorrhage or stroke. The most common treatment is resection, which is the complete removal of the AVM from the brain through a craniotomy. This procedure guarantees the complete elimination of the AVM, but often comes with a high mortality rate and leaves survivors with debilitating disabilities, as AVMs are often embedded within the victim’s brain tissue and must be removed at the cost of some of the victim’s brain tissue.

Another more modern, less invasive technique for the treatment of smaller, less serious AVMs is Stereotactic radiosurgery (SRS). This treatment uses precisely concentrated electromagnetic radiation of specific frequencies to destroy the AVM. SRS requires no incision or surgery to perform. Instead, SRS directs many precisely adjusted radiation beams at the AVM to damage the blood vessels and cause scarring. The scarred AVM blood vessels then slowly clot off in the years following treatment.

This treatment isn’t appropriate for those with large AVMs, however, as it can take many years to destroy those with SRS, and larger AVMs have a great risk of rupturing over several years, and thus call for more urgent action.

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While AVMs affect less than 1% of the population, their effects can be devastating for victims and their families. Even though it only takes a 15-minute Brain MRI to detect an AVM, close to 0% of AVMs are proactively detected and treated before rupture. This is largely due to a lack of awareness of this uncommon, yet dangerous, condition. It is thus important to spread awareness of this destructive, elusive condition, as thousands around the world can be saved through awareness of its warning signs, symptoms, and dangers.

Vivian Lu