When veins and arteries don't form correctly and become entangled during development, the result is a condition known as an arteriovenous malformation (AVMs). 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. Spinal arteriovenous malformations affect the spinal cord. AVMs that occur in the brain can cause problems throughout the body because they affect the nervous system.
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. Only about 300 people a year need hospital care because of a spinal AVM.
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.
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 usually involves a combination of surgery (by a neurosurgeon) and endovascular embolization, or plugging the vessels with a catheter (by a radiologist). Radiation therapy is also an option.
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.
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.