Cerebral infarction, also known as ischemic stroke, occurs when the blood vessels that supply the brain are disturbed so that blood flow is interrupted. There are two common types of ischemic stroke: atherothrombotic, and embolic, as well as other less common causes. The cause of an ischemic stroke cannot be determined in approximately 40% of cases.
Infarction is a medical term which describes the necrosis that occurs when blood supply to tissues is interrupted. Blood supply can be interrupted in a number of ways, such as blockage of a supplying artery, mechanical compression of an artery by a tumor or hernia, or rupture of an artery due to trauma. Brain infarction is often associated with atherosclerosis or high blood pressure.
Cerebral infarction occurs when the blood supply to the brain is interrupted. Within minutes, a series of reactions known as the ischemic cascade begins, and can continue for several hours, and may even last for days. The brain is still vulnerable even when the blood supply is restored, due to the possibility of reperfusion injury.
During the ischemic cascade oxygen deprivation leads to the absence of ATP in the brain’s tissues. ATP proton pumps fail, allowing a massive influx of calcium ions into cells. This results in the generation of reactive oxygen species, free radicals, and other harmful chemicals. Eventually cells begin to die, some via necrosis, which triggers an inflammatory response which can itself cause further damage to brain tissue. The ischemic cascade can occur in any type of tissue, but the brain is considered most vulnerable due to its complete dependence on aerobic metabolism.
Cerebral infarction can occur for several different reasons. The formation of a thrombosis, or blood clot, in an artery or blood vessel that feeds the brain can result in an interrupted blood supply. Embolism, in which a portion of thrombosis breaks off and causes a blockage, is another common cause infarction. Cerebral venous sinus thrombosis, in which blood vessels that drain the brain become blocked, may result in cerebral infarction as blood fails to recirculate in the body.
Symptoms are fairly distinctive. Interruption of the blood supply to the brain can cause muscle weakness in the face and other parts of the body, tingling or numbness, inability to speak or understand speech, confusion, and memory disturbances. Diagnosis is usually made on the basis of symptom evaluation and neurological exams, as well as medical imaging tests such as CT or MRI.
Treatment of ischemic stroke may involve breaking down or removing a thrombosis or embolus, and administering medication to prevent further clots. A large portion of brain infarction treatment is supportive in nature, as many people suffer brain tissue damage that requires rehabilitative therapy. Some people find they must relearn how to walk, talk, and carry out other everyday activities, while others may have to adjust to the permanent loss of such abilities.