What is Arteriovenous Malformations?
Arteriovenous malformations (AVM) of the brain and spinal cord affect approximately 300,000 Americans. They are tangles of abnormal blood vessels. Arteriovenous malformations can form wherever arteries and veins exist. However, the ones that form in the brain or spinal cord can have especially serious effects.
Blood flows through arteries, bringing oxygen from the heart to the brain. The blood then enters smaller blood vessels that slow the blood flow and allow oxygen to be delivered to the surrounding tissue. Finally, the veins carry the oxygen depleted blood away from the brain to the heart and lungs to pick up more oxygen.
Arteries in arteriovenous malformations don’t follow this pattern. They dump blood directly into veins through a channel called a fistula, an abnormal tube-like opening. The blood flow through this fistula is extremely fast. Complications from this include:
- Uncontrolled flow that doesn’t allow oxygen to be delivered
- Extreme blood flow puts a great deal of pressure on the wall of the blood vessels and may cause them to rupture and bleed (hemorrhage)
Two to four percent of all arteriovenous malformations hemorrhage or bleed. The damage caused by the bleeding depends on where the arteriovenous malformation is located. If the hemorrhage is in the brain, brain tissue can be damaged. It may be temporary or permanent damage.
Arteriovenous malformations can seriously damage the brain and the spinal cord by:
- Reducing the amount of oxygen reaching the brain
- Causing bleeding (hemorrhage) into the tissues that make up the neurological system (the nervous system, including the brain and spinal cord)
- Pressing against or moving parts of the brain or spinal cord
Complications of arteriovenous malformations include strokes (blood supply and oxygen are totally cut off from the brain), hydrocephalus (excessive build-up of fluid within the brain), and spinal cord injury (possibly causing paralysis).
The sooner arteriovenous malformations are treated, the better the outcome. If you suspect you have this condition, contact your doctor immediately.