http://www.mayoclinic.com/invoke.cfm?id=DS00220
Mayo Foundation for Medical Education and Research
About one in three people who have a Transient Ischemic Attack (TIA), which is sometimes called a ministroke, eventually have a stroke, with about half occurring during the year after the TIA. A TIA can serve as both a warning and an opportunity — a warning of an impending stroke and an opportunity to take steps to prevent it.