Arteriovenous malformations (AVMs) occur when the connections between veins and arteries don't form correctly and become entangled. Usually, veins and arteries develop these abnormalities as a fetus grows in the womb or just after a baby is born.
AVMs can occur anywhere in the body. But when they happen in the spinal cord and brain, called neurological AVMs, they are more likely to have effects on the body. This is because the brain and spinal cord make up the central nervous system. About 300,000 Americans are affected by neurological AVMs.
Facts about spinal arteriovenous malformations
AVMs are equally common among different races and ethnicities, and in both sexes. Most people don't even know that they have a spinal AVM—it may be found during treatment or diagnosis for another condition. Their size can vary from much less than an inch to 2.5 inches. Fewer than 15 percent of people with neurological AVMs will have symptoms or complications.
Spinal AVMs can cause problems with circulation because they interfere with the body's blood flow. Normally, arteries transport oxygen-rich blood away from the heart and to cells throughout the body. The veins bring that blood, with its oxygen stores used up, back to the lungs and heart. But the malformations of the arteries and veins in spinal AVMs don't allow this natural cycle to occur because of missing capillaries, which regulate blood flow.
Spinal AVMs can also lead to a serious situation if they rupture, causing bleeding into surrounding areas. They can also cause symptoms by compressing parts of the spinal cord.
When symptoms occur
Spinal AVMs don't often cause any symptoms. When they do, they're often minor and difficult to notice. In a small number of people, however, the symptoms can be severe enough to affect their ability to function.
These are the most common symptoms of a spinal AVM:
Muscles that feel weak or become paralyzed
Ataxia, a condition in which you have problems with balance and coordination
Pain or unusual sensations throughout your body, such as tingling or numbness
If you experience symptoms, your doctor may use these tests to diagnose a spinal AVM:
Angiography (X-rays used in combination with a dye injected into an artery)
Magnetic resonance angiography
Treatment may involve a combination of surgery by a neurosurgeon, or endovascular embolization, which is less invasive and involves plugging the vessels with a catheter by a radiologist. Radiation therapy is also an option. The type of surgery you have depends on the location and size of the AVM.
Your doctor may also give you medications to treat symptoms, such as back pain, caused by AVMs.
Calling the doctor
Any signs or symptoms that indicate a problem with your nervous system, such as headaches that won't go away, seizures, and difficulty controlling your muscles, should generally be evaluated by your doctor.
If spinal AVMs aren't treated, they may cause damage to the spinal cord because it can't get the oxygen it needs from your blood. A spinal AVM may also hemorrhage and leak blood.
Key points to remember
Even though a spinal AVM may not always cause symptoms, it can still be dangerous, particularly if it starts to cause symptoms. You should have any suspicious symptoms checked out by your doctor.