A stroke involves brain damage caused by a loss of blood circulation to an area of the brain. The blockage usually occurs when a clot or (less often) piece of atherosclerotic plaque breaks away from an artery elsewhere in the body and lodges within the vasculature of the brain.
Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.