This triggers an increase in concentration of calcium within cells. This results in activation of messengers and genes that set in motion a series of events that results in cell death, as well as a spreading of the process to adjacent cells. The ischemic cascade kills brain cells quickly in the stroke's core area and endangers cells more slowly in a larger surrounding area of brain tissue for which blood supply is compromised but not completely cut off. Prompt medical treatment may save brain cells in this surrounding area, called the penumbra. Numerous studies have found that most people don't know crucial information about stroke, such as preventative measures and recognition of symptoms that could save their lives or those of loved ones.
Many strokes are preventable by controlling major risk factors.
High blood pressure, or hypertension, increases the risk of stroke four to six times above normal. Hypertension is common, affecting one in three adults in the United States, but it can usually be controlled by medication. High levels of blood cholesterol increase stroke risk directly and indirectly. Deposits of cholesterol on artery walls increase the risk of thrombotic stroke. High cholesterol levels are also associated with greater risk of heart disease.