http://www.ninds.nih.gov/disorders/cavernous_malformation/cavernous_malformation.htm
National Institute of Neurological Disorders and Stroke, National Institutes of Health
This page is a backgrounder on cavernous malformation, a rare disorder of the capillaries and smallest veins in one part of the brain. The disorder occurs when a blood-filled mass resembling a tumor, called a hemangioma, forms. Symptoms include headaches and seizures.