About one-third of the people with TIA will later have a stroke. The age of onset varies, but incidence rises dramatically after age 50. TIA is more common among men and African-Americans. The microemboli are caused by atherosclerotic plaque in the arteries that supply the brain. Atherosclerotic plaque is formed when damage occurs to the lining of an artery.
Platelets clump around the area of injury as a normal part of the clotting and healing process.
Cholesterol and other fats also collect at this site, forming a mass within the lining of the artery. Pieces of plaque or clots may break off and travel through the bloodstream from distant locations, forming an embolus that can occlude the small arteries, causing TIAs. Occlusions that last for more than a few minutes more commonly cause stroke. Symptoms may occur again at a later time. Symptoms usually occur on the same side of the body if more than one body part is involved.