When a knot of malformed or otherwise abnormal blood vessels occurs it’s known as arteriovenous malformation. Such knots—believed to result when an artery connects to a vein without the necessary capillaries—are likely to bleed, and therefore when they occur in the brain they can be very serious and potentially life threatening.

Because they are formed in the pre-natal stage, arteriovenous malformations typically accompany abnormal development of brain tissues. Occurring in less than one percent of the population, the size and location of arteriovenous malformations can vary and the signs and symptoms of the condition can present at any age.

The danger of arteriovenous malformation is that they can rupture or burst from pressure, which likely will cause damage to the surrounding tissues and thereby reduce the flow of blood to the brain. In terms of signs and symptoms of the condition, they are dependent on the size and location of the anomaly (in some cases there may be no signs or symptoms at all). But when markers of the problem are present, sufferers will most likely have seizures (a result of a disturbance of the electrical activity in the brain); headaches from increased blood flow; and signs that mimic a stroke, including paralysis or weakness on one side of the body, sensation, hearing, vision and balance problems and a loss of memory or drastic change in behavior.

Various forms of angiography—in which a dye is injected into the blood in conjunction with imaging technologies that detect the size and location of the arteriovenous malformation—are used in diagnosing the condition, and treatment can take several forms. Often, a liquid/glue substance is injected into the arteriovenous malformation to block it off, and sometime the abnormality is bombarded with x-rays in order to reduce its size. And in surgical situations the arteriovenous malformation is removed completely.