Cerebral ischemia is a condition in which a blockage in an artery restricts the delivery of oxygen-rich blood to the brain, resulting in damage to brain tissue. Cerebral ischemia is sometimes called brain ischemia or cerebrovascular ischemia.
Cerebral ischemia can lead not only to brain-cell damage but to brain-cell death. A transient ischemic attack (TIA), also known as a mini-stroke, is when the cerebral ischemia causes the temporary loss of brain function. An ischemic stroke, also known as a cerebral infarction or brain attack, results when a blood vessel is occluded and the loss of brain function is permanent because the brain tissue dies (sometimes called necrosis). Ischemic strokes are the most common form of stroke.
What Causes Cerebral Ischemia?
Blood clots are often the source of the blockages that lead to cerebral ischemia. Normal function of the brain requires an adequate supply of oxygen-rich blood, which is delivered through two major sets of blood vessels known as the internal carotid arteries and the vertebrobasilar system (consisting of two vertebral arteries and the basilar artery).
There are many medical conditions associated with blood clots:
Some severe infections, a ruptured blood vessel, or trauma that results in a large loss of blood can lead to low blood pressure (hypotension) and reduce blood flow to the brain.
Types of Ischemia:
Decreased blood flow can be confined to just one particular region of the brain; this type of cerebral ischemia is called focal ischemia. It can be caused by a thrombosis, which is a blood clot in one of the cerebral arteries that restricts blood flow to one area. An embolism, which is a small piece of a clot that breaks off and travels -- eventually becoming stuck or severely limiting blood flow -- can also cause a focal ischemia.
Global ischemia, on the other hand, describes the condition in which wide areas of the brain are being deprived of oxygen-rich blood. It can be caused by cardiac arrest (when the heart stops beating) or a heart attack (when blood flow to the heart is blocked).
Reviewed by: Dr. Philip E. Stieg
Last reviewed/updated: October 2020
Illustration by Thom Graves