An arteriovenous malformation (AVM) is a localized tangle of arteries and veins connected directly to each other with no capillaries (branching, delicate blood vessels) in between. In the vascular system, arteries carry oxygen-rich blood away from the heart and circulate it to the other organs. Veins then bring oxygen-depleted blood back to the heart and lungs. Normally, capillaries connect arteries to veins, supporting healthy circulation. AVMs disrupt this process, diverting blood through abnormal blood vessels and causing it to bypass the surrounding normal tissue.
The cause of AVMs is unknown. They are usually congenital (emerging during fetal development) but not hereditary (inherited from parents or passed on to children). AVMs can occur anywhere, including the brain or spinal cord. Still, brain AVMs are rare, affecting less than 1 percent of the population. Some people with brain AVMs will experience symptoms such as localized headaches, seizures or difficulty with movement, speech or vision. For about 50% of all brain AVMs, however, hemorrhage is the first sign.
In an AVM, the weakened blood vessels joining arteries to veins dilate (widen) over time. Eventually they may rupture, causing bleeding in the brain—intracranial hemorrhage. Hemorrhage is the greatest danger AVMs present, as normal brain tissue is damaged each time an AVM bleeds. This damage can result in temporary or permanent loss of normal function, including limb paralysis or difficulty with vision, speech, memory, coordination or comprehension. A bleeding AVM is a life-threatening emergency. Therefore, it is important to treat an AVM before it has hemorrhaged.
While the yearly risk of hemorrhage is low (1 percent to 3 percent), over time this risk adds up. Fortunately, treatment is possible. For AVMs that are small and difficult to reach, one option is Gamma Knife radiosurgery. Don’t let the name fool you—there are no knives involved in Gamma Knife. Noninvasive Gamma Knife treatment uses focused beams of gamma radiation to damage the AVM’s abnormal blood vessels, causing them to scar and clot, eliminating the risk of hemorrhage. At the Boston Gamma Knife Center at Tufts Medical Center, we use this state-of-the-art technology to provide radiation-based treatment that is safe and effective.
Programs + Services
The Neurovascular Surgery Program at Tufts Medical Center in Boston, MA provides world-class minimally invasive surgical, endovascular, and radiosurgical treatment for diseases that occur in the blood vessels that supply the brain and spinal cord with oxygen and nutrients.
The Boston Gamma Knife Center offers radiosurgery to treat brain tumors and vascular malformations without incisions or traditional brain surgery.