There are different forms of ischemic stroke: lacunar, thrombotic and embolic strokes. Lacunar strokes are associated with insufficient blood supply reaching the brain through small arteries. Thrombotic strokes - which account for half of all stroke incidences - occur when an artery to the brain is occluded (blocked) by a blood clot. Embolic strokes, on the other hand, occur when a blood clot or a piece of artherosclerotic plaque breaks loose and travels (embolism) through open arteries to lodge in an artery of the brain.
Other forms of stroke are also possible, however. These include cerebral hemorrhaging, subarachnoid hemorrhaging, cerebral vasculitis and transient ischemic attack (TIA). Strokes are medical emergencies - if any symptoms of a stroke appear, do not hesitate to seek medical help.