What is a brain AVM?
Normally, arteries carry blood containing oxygen from the heart to the brain, and veins carry blood with less oxygen away from the brain and back to the heart. When an arteriovenous malformation (AVM) occurs, a tangle of blood vessels in the brain or on its surface bypasses normal brain tissue and directly diverts blood from the arteries to the veins. Less than 1 percent of the general population have brain AVMs. Males more than females experience this condition.
Brain AVMs are usually congenital, meaning someone is born with it, but they are usually not hereditary.
What are the symptoms of a brain AVM?
Symptoms may vary depending on where the AVM is located:
- An intracranial hemorrhage (buildup of blood within the skull) is a common condition that more than 50 percent of AVM patients have.
- 20 percent to 25 percent of AVM patients have focal or generalized seizures.
- Patients may have localized pain in the head due to increased blood flow around an AVM.
- 15 percent may have difficulty with movement, speech, and vision.
In people without hemorrhage, signs and symptoms of a brain AVM may include:
- Headaches or pain in a certain part of the head;
- Muscle weakness or numbness in one part of the body.
Some people may experience more serious neurological signs and symptoms, depending on the location of the AVM, including:
- Severe headaches;
- Weakness, numbness or paralysis;
- Vision loss;
- Difficulty speaking;
- Confusion or inability to understand others;
- Severe unsteadiness.
What are the causes of a brain AVM?
Researchers believe most brain AVMs emerge during fetal development. Normally, your heart sends oxygen-rich blood to your brain through arteries. Naturally, your heart beats and oxygen-rich blood is delivered to your brain through arteries. The blood flow is slow down as much as the blood travels far from arteries through a series of progressively smaller networks of blood vessels, ending with the smallest ones called capillaries. Through thin, porous walls of these tiny vessels, oxygen is lead to the surrounding brain tissue.
The oxygen-depleted blood then follows the small blood vessels to larger veins that drain the blood from your brain, returning it to your heart and lungs to get more oxygen.
The arteries and veins in an AVM lack this supporting network of smaller blood vessels and capillaries. Instead, the abnormal connection causes blood to flow quickly and directly from your arteries to your veins, bypassing the surrounding tissues.
What are the risk factors of a brain AVM?
Anyone can be born with a brain AVM, but these factors may be risks:
- Being male. AVMs are more common in males.
- Having a family history. Cases of AVMs in families have been reported, but it is unclear if there is a certain genetic factor or if the cases are only coincidental.
Seek medical attention immediately if you notice any sign or symptom of a brain AVM, such as seizures, headaches or other symptoms listed above. A bleeding brain AVM is life-threatening and requires emergency medical attention.
Hello Health Group does not provide medical advice, diagnose or treatment.
Review Date: September 23, 2016 | Last Modified: December 4, 2019
What Is an Arteriovenous Malformation (AVM)? http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/HemorrhagicBleeds/What-Is-an-Arteriovenous-Malformation-AVM_UCM_310099_Article.jsp#.V9Web_l97IU. Accessed September 23, 2016.
Brain AVM (arteriovenous malformation). http://www.mayoclinic.org/diseases-conditions/brain-avm/symptoms-causes/dxc-20129994. Accessed September 23, 2016.