What is an ischemia? |

Causes and Symptoms

When a localized area of the brain does not receive enough blood, neurons and supportive tissue such as glia are deprived of the essential oxygen and glucose that keep them alive. If the brain does not receive sufficient blood for even a few minutes, the result is an ischemic stroke.

Although it is possible for ischemia to have no detectable symptoms, when it occurs to the internal carotid, middle cerebral, or vertebral-basilar arteries, symptoms such as confusion, impaired speech, double vision, or numbness on one side of the face can be experienced. In some instances, these symptoms are temporary and do not result in permanent damage (these are called transient ischemic attacks, or TIAs), but if the interruption of blood flow lasts long enough, permanent damage (a stroke) occurs. If blood flow is restricted to the coronary artery of the heart (cardiac ischemia), then the heart muscle may suffer permanent damage (myocardial infarction). Symptoms of cardiac ischemia may include chest pain.

Ischemia is commonly caused by the formation of blood clots or by atherosclerosis, in which the walls of the arteries become narrowed as a result of the buildup of fat deposits.

Treatment and Therapy

The risk of ischemia can be assessed with high-resolution ultrasound equipment or magnetic resonance angiography (MRA) to detect blood flow. It is common to use computed tomography (CT) scanning or magnetic resonance imaging (MRI) to visualize damaged brain tissue and determine if the damage is ischemia caused by a blocked blood vessel or by a burst blood vessel (cerebral hemorrhage). Cardiac ischemia can be diagnosed by electrocardiography, echocardiography, or angiography. Drug therapies such as administering aspirin or stronger blood-thinning agents help when ischemia is caused by clotting. Nitroglycerin can quickly open up coronary arteries and reduce the chest pain experienced when the heart is affected. Drugs that lower blood pressure are also helpful treatments.

Surgery might be needed to correct an obstruction that cannot be dissolved. Angioplasty can be used to expand affected arteries, particularly when the cause is atherosclerosis.

Perspective and Prospects

Rudolf Virchow, a nineteenth century German physician, was the first to use the term ischemia. Since the time that ischemia was originally identified, diagnostics have been improved through the use of echocardiograms that send out sound waves to create an image of the heart’s internal structures and through angiograms that can pinpoint the area of arterial narrowing. Treatment improvements for damage to the brain include the administration of unique drugs that can mitigate damage to surrounding nerve cells indirectly affected by the lack of blood.

Much has been learned about the need for a balanced diet, for regular exercise, for controlling hypertension, and for preventing or treating atherosclerosis as means to reduce the likelihood of suffering from an ischemic attack.

Bibliography

American Heart Association. Heart Attack Treatment, Prevention, Recovery. New York: Times Books, 1998.

Anagnostopoulos, Constantinos D., et al., eds. Noninvasive Imaging of Myocardial Ischemia. London: Springer, 2006.

Blumenfeld, Hal. Neuroanatomy Through Clinical Cases. 2d ed. Sunderland, Mass.: Sinauer, 2011.

Caplan, Louis R. "Patient Information: Ischemic Stroke Treatment (Beyond the Basics)." UpToDate, February 1, 2012.

Kalat, James W. Biological Psychology. 11th ed. Belmont, Calif.: Wadsworth, 2013.

Kolb, Bryan, and Ian Q. Whishaw. Fundamentals of Human Neuropsychology. 6th ed. New York: Worth, 2009.

MedlinePlus. "Transient Ischemic Attack." MedlinePlus, April 29, 2013.

Texas Heart Institute at St. Luke's Episcopal Hospital. "Silent Ischemia." Heart Information Center, October 2012.

Zillmer, Eric A., and Mary V. Spiers. Principles of Neuropsychology. 2d ed. Belmont, Calif.: Thomson/Wadsworth, 2008.