When Blood Vessels Grow Awry

Understanding Vascular Malformations

Blood vessels wind all throughout your body. They ensure that blood, and the oxygen it carries, reaches all your body’s cells and tissues. Arteries carry oxygen-rich blood from your heart to organs and tissues. Veins carry blood back to your heart to pick up more oxygen. And tiny vessels called capillaries connect the arteries to the veins.

But sometimes, the blood vessels don’t grow quite right. When blood vessels in the brain form in an abnormal way, it’s called a vascular malformation.

Several types of vascular malformations exist. Some pose little risk. But two types can be at increased risk of leaking or breaking open. This can cause bleeding in the brain, which can lead to brain damage or death. These are arteriovenous malformations, or AVMs, and cerebral cavernous malformations, or CCMs (also called cavernous angiomas).

In AVMs, arteries bypass capillaries and connect directly to veins. They’re like short circuits in your circulation. Blood then rushes into veins much faster than usual. This leads to high blood pressure in the vessels.

In CCMs, capillaries in the brain can balloon over 20 times their usual width. Blood pools in these enlarged capillaries. The walls can get stretched to the breaking point.

Both AVMs and CCMs strain blood vessel walls, increasing the chance of the vessels breaking. They can also put pressure on parts of the brain.

AVMs and CCMs are rare. Each affects less than 1% of people. Many people who have them may not know it. Most people with AVMs or CCMs have only mild symptoms, such as headaches or dizziness. They may have no symptoms at all. But once a malformation starts to leak out blood, it can cause seizures or strokes. It also becomes more likely to bleed again. See the Wise Choices box for more symptoms.

Vascular malformations can sometimes be removed or repaired with surgery. Doctors may also be able to use a focused beam of radiation to destroy them. Some AVMs can be plugged with a type of glue delivered through a tube inserted in an artery. But these procedures can be risky, especially if the malformation is deep inside the brain.

If a malformation has not already bled, the safest course may be to just keep an eye on it. Medications can help with some symptoms, like headaches and seizures.

“It all depends on where the malformation is in the brain, and what is the risk of treatment versus watching,” explains Dr. Issam Awad, a neurosurgeon at the University of Chicago.

Awad researches the underlying causes of vascular malformation development and bleeding. Sometimes gene abnormalities are involved. His team is looking at whether gut bacteria may play a role. They’ve shown that people with CCMs have different kinds of gut bacteria than those without CCMs. They’ve also found certain molecules in the blood that are linked with these bacteria. His team hopes that these molecules might someday be used to test whether someone will develop CCMs, or whether a CCM is likely to bleed.

But for now, talk with your health care provider if you’re concerned about a family history or symptoms of a vascular malformation.