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Brain ischemia has been linked to a variety of diseases or abnormalities. Individuals with sickle cell anemia, compressed blood vessels, ventricular tachycardia, plaque buildup in the arteries, blood clots, extremely low blood pressure as a result of heart attack, and congenital heart defects have a higher predisposition to brain ischemia in comparison to the average population.
Because the brain would quickly suffer damage from any stoppage in blood supply, the cerebral circulatory system has safeguards including autoregulation of the blood vessels. The failure of these safeguards may result in a stroke. The volume of blood in circulation is called the cerebral blood flow.
Atrial fibrillation causes blood clots to form within the heart, which may travel to the arteries within the brain and cause an embolism. The embolism prevents blood flow to the brain, which leads to a stroke. [26] An aneurysm is an abnormal bulging of small sections of arteries, which increases the risk of artery rupture.
Brain ischemia is insufficient blood flow to the brain, and can be acute or chronic. Acute ischemic stroke is a neurological emergency typically caused by a blood clot blocking blood flow in a vessel in the brain. [15] Chronic ischemia of the brain may result in a form of dementia called vascular dementia. [16]
Stroke is a medical condition in which poor blood flow to a part of the brain causes cell death. [5] There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. [5] Both cause parts of the brain to stop functioning properly. [5]
Blood pressure should be lowered a maximum of 10% over the first hour and 25% over the first two hours as rapid lowering of blood pressure can lead to decreased blood flow in the brain and cause the development of an ischemic stroke. Once blood pressure is stabilized, patients can be changed from intravenous medications to oral. [3]
Another factor in secondary injury is loss of cerebral autoregulation, the ability of the brain's blood vessels to regulate cerebral blood flow. [5] Other factors in secondary damage are breakdown of the blood–brain barrier, edema, ischemia and hypoxia. [15] Ischemia is one of the leading causes of secondary brain damage after head trauma. [9]
An inflammatory response is mounted, and phagocytic cells engulf damaged but still viable tissue. Harmful chemicals damage the blood–brain barrier. Cerebral edema (swelling of the brain) occurs due to leakage of large molecules like albumins from blood vessels through the damaged blood brain barrier.