Arteriovenous malformation is an congenital disorder of blood vessels in the brain, brainstem, or spinal cord that is characterized by a complex, tangled web of abnormal arteries and veins connected by one or more fistulas. Arteriovenous malformations are blood vessel defects that occur before birth when the fetus is growing in the uterus. The blood vessels appear as a tangled mass of arteries and veins. They do not possess the capillary bed which normally exists in the common area where the arteries and veins lie in close proximity. An arteriovenous malformation may hemorrhage, or bleed, leading to serious complications that can be life-threatening.
In a normal functioning human body, arteries carry blood away from the heart to the lungs or the rest of the body, where the blood passes through capillaries, and veins return the blood to heart. An AVM interferes with this process by forming a direct connection of the arteries and veins. AVMs can cause intense pain and lead to serious medical problems. Although AVMs are often associated with the brain and spinal cord, they can develop in any part of the body.
Treatment for brain AVMs can be symptomatic, and patients should be followed by a neurologist for any seizures, headaches or focal deficits. AVM-specific treatment may also involve endovascular embolization, neurosurgery or radiosurgery. Embolization, that is, cutting off the blood supply to the AVM with coils or particles or glue introduced by a radiographically guided catheter, may be used in addition to neurosurgery or radiosurgery, but is rarely successful in isolation except in smaller AVMs. Gamma knife may also be used. The estimated detection rate of AVM in the US general population is 1.4/100,000 per year.