"Infarction" is a medical term for tissue damage due to occlusion of an artery supplying that tissue. It can apply to any tissue, a renal infarction being damage to some part of a kidney in this way. One only hears the term commonly, though, for the heart and the brain. A myocardial infarction is damage to heart muscle, the myocardium. This is what's commonly called a heart attack. An infarction of the brain is damage to brain tissue from lack of blood supply from a single artery, called "ischemia", the most common form of what is commonly called a stroke.
Infarction of the brain is divided into damage to the cerbral cortex, called "cerebral infarction" and damage to the lower parts of the brain, called "brainstem infarction". The former is generally supplied by the carotid arteries while the latter is supplied by the vertebral arteries.
Infarction can occur due to thrombosis, in which an artery closes off due to atherosclerosis, or embolism where a blood clot or other material travels to an artery feeding the brain, usually from the heart. The artery causing the infarction may remain occluded or may clear, but still having been occluded long enough to cause infarction.
Symptoms of brain infarction depend on the location of the tissue damaged. They may include weakness, inability to speak, reduced vision, double vision, dizzyness, imbalance, altered sensation or confusion. The best treatment of brain infarction depends on patients presenting to the emergency room within 3 hours of such symptoms, the sooner the better.
Recovery from brain infarction depends on how reversible the damage to the brain tissue is. Many small infarctions improve over weeks to months. Old, small infarctions may be discovered on CT or MRI scans, apparently having occurred in the past without symptoms. Large infarctions may cause patients considerable symptoms, which may still be improving at least two years after the stroke.