Arteriovenous Malformations (동정맥 기형)

Arteriovenous malformations (AVMs) are short circuits in the circulatory system believed to arise during fetal development or shortly after birth. Most of the suspected 300,000 people with AVMs exhibit minor - if any - symptoms, but about 12 percent of cases can result in headaches, seizure, stroke, or even death. The malformations can form anywhere in the body, but are especially dangerous when they occur in the brain.

 

AVMs are areas that lack the tiny capillaries, where blood flows straight from the artery (heading away from the heart) into the vein (heading back toward the heart). The location of this connection between artery and vein is called a fistula, or shunt. The nearby area of tissue, which misses out on blood and nutrients, is called the nidus of the AVM.

 

Though headaches and seizures are the most common signs of AVMs, these malformations can cause a wide range of other symptoms - including muscle weakness, loss of coordination, memory deficits, hallucinations, and mental impairment - depending on their locations in the body.

 

Each year, about 4 percent of people with AVMs experience hemmoraging, or internal bleeding, when increased blood pressure and flow cause fistula vessels to rupture. Most episodes are not severe enough to produce significant damage, but some may cause a stroke or altered bloodflow, sparking progressive neurological problems.

 

Some of the symptoms of AVM can be eased by medications, but surgery is the only true way to treat them. However, surgery of the central nervous system carries its own risks. Whenever an AVM is detected, the patient should be monitored carefully for signs that may indicate an increased risk of hemorrhage.

 

Three surgical options exist for the treatment of AVMs ;  Conventional surgery is best for relatively small AVMs in superficial portions of the brain or spinal cord. For anything larger or in a riskier area, embolization (introducing a glue, coil, or tiny ballon into the bloodstream through a tiny catheter to form a clot and divert bloodflow) or radiosurgery (aiming high-dose beams of radiation at the AVM to alter the blood vessel walls) is usually performed in lieu of or in addition to conventional surgery.

 

An AVM can be detected by a CT scan or an MRI. But because so few people experience symptoms, most AVMs are discovered accidentally during examination for another condition or during autopsy after death.

 

There are some genetic conditions known to cause AVMs, such as Osler-Weber-Rendu disease and polycystic kidney disease.