These are defects of the circulatory system that are generally believed to arise during embryonic or fetal development or soon after birth. AVMs damage the brain or spinal cord through three basic mechanisms: by reducing the amount of oxygen reaching neurological tissues; by causing bleeding (hemorrhage) into surrounding tissues; and by compressing or displacing parts of the brain or spinal cord. The greatest potential danger posed by AVMs is hemorrhage. Researchers believe that each year 2%–4% of all AVMs hemorrhage. However, even in the absence of bleeding or significant oxygen depletion, large AVMs can damage the brain or spinal cord simply by their presence.
Neurosurgeons now use a variety of traditional and new imaging technologies to uncover the presence of AVMs. These include angiography, computed axial tomography (CT) and magnetic resonance imaging (MRI) scans. Today, three surgical options exist for the treatment of AVMs: conventional surgery, endovascular embolization, and radiosurgery. The choice of treatment depends largely on the size and location of the anomaly. Surgery is most appropriate when an AVM is located in a superficial portion of the brain or spinal cord and is relatively small in size. Endovascular embolization and radiosurgery are less invasive than conventional surgery and offer safer treatment options for some AVMs located deep inside the brain.