If you were to imagine your blood vessels as a complex series of highways meant to transport oxygen and nutrients throughout the body, an arteriovenous malformation (AVM) is what would happen if those highways were to suddenly become tangled and wrapped together. This is a rare condition that creates abnormal connections between the arteries and veins and can lead to a widening of the vessels, ultimately forming aneurysms (balloon-like bulges that can burst and cause internal bleeding into the brain).
Most AVMs are present at birth, though they aren’t usually identified until later in life. They can occur anywhere in the body but are most common in the spinal cord or brain. Over time, arteriovenous malformations become more and more dangerous. The cause of AVMs is unknown, though it is thought that they may be created by a rupture or clotting of a blood vessel during development, while still in the womb.
Not everyone with an AVM will experience symptoms, and some AVMs are discovered only when an MRI is performed for other reasons. For those who do experience symptoms as a result of arteriovenous malformation, those symptoms may include:
- Painful, persistent headache
- Slurred speech
- Loss of consciousness
- Muscle weakness or paralysis
- Loss of coordination
- Visual disturbances
- Language disruptions
- Loss of memory
- Mental confusion
These symptoms typically appear during an AVM event, such as when the AVM has already started to bleed. This can happen at any age, though two thirds of AVM events occur before the age of 40.
While they can remain undetected for quite some time, AVMs do pose a serious risk. Brain hemorrhaging occurs in about four out of every 100 people with arteriovenous malformation annually. Each hemorrhaging event presents a 15 to 20 percent risk of death or stroke. Other risks include:
- Reduced oxygen delivery to the brain or spinal cord
- Microbleeds, which can go undetected but contribute to dementia and cognitive disruption
- Damage to the brain or spinal cord, even when no bleed or significant depletion of oxygen occurs
Many arteriovenous malformations are first detected via MRI. If an AVM is suspected without an MRI, your doctor may listen for a rhythmic, whooshing sound that is distinctive to the rapid blood flow surrounding an AVM. In both cases, a cerebral angiography must be performed in order to confirm diagnosis (use of X-rays and contrast material to produce pictures of blood vessels in your brain).
Given the risks involved with AVM, your doctor will almost always recommend some form of treatment once an AVM is discovered. Those options include:
- Endovascular Embolization: During this procedure, your interventional neuroradiologist uses X-ray guidance to insert a catheter (small tube) into your leg, and guide it up the femoral artery into the area to be treated. Typically this is used as a preliminary treatment before microsurgical resection, and it is meant to make surgery safer.
- Microsurgical Resection: This is a precise and minimally invasive procedure meant to remove the AVM, and it has the highest cure rate of any treatment option. During the procedure, your physician removes a small section of your skull to enter your brain and remove the AVM.
CyberKnife Radiosurgery: This is a noninvasive treatment that involves using targeted radiation over the course of two to three years. CyberKnife radiosurgery has a good cure rate and is used most often for small AVMs located in areas of the brain that are less safe to perform surgery on.