A transient ischemic attack (TIA), commonly known as a mini-stroke, is a brief episode of neurological dysfunction caused by loss of blood flow (ischemia) in the brain, spinal cord, or retina, without tissue death (infarction). TIAs have the same underlying mechanism as ischemic strokes. Both are caused by a disruption in blood flow to the brain, or cerebral blood flow (CBF). The definition of TIA was classically based on duration of neurological symptoms. The current widely accepted definition is called "tissue-based" because it is based on imaging, not time. The American Heart Association and the American Stroke Association (AHA/ASA) now define TIA as a brief episode of neurological dysfunction with a vascular cause, with clinical symptoms typically lasting less than one hour, and without evidence of infarction on imaging.