Its symptoms resemble those of a stroke, but the symptoms go away within minutes or hours. TIAs should be considered warning signals for seeking prompt medical intervention to delay or prevent a disabling stroke. Ischemic strokes can be caused by narrowing or clogging of blood vessels supplying the brain with oxygen and nutrients. Just as cholesterol and calcium debris can build up in arteries in the heart to cause vessel narrowing and a heart attack, atherosclerosis can narrow brain arteries to cause a brain attack and death of brain tissue due to decreased blood flow. This is called an embolism.
Heart arrhythmias can contribute to such clotting, as can heart attacks.
An embolism generally causes a sudden and severe onset of symptoms. Yet other strokes occur in tiny vessels serving minuscule portions of the brain. These are called lacunar strokes. High blood pressure, smoking and diabetes can contribute to thickening of these vessels. Because such strokes damage smaller areas of the brain at a time, their effect may be only isolated weakening of muscles or numbness on one side.