Ischemic brain (a.k.a. cerebral ischemia , cerebrovascular ischemia ) is a condition in which there is not enough blood flow to the brain to meet metabolic demand. This results in poor oxygen supply or cerebral hypoxia and thus brain tissue death or cerebral infarction/ischemic stroke. This is a sub-type of stroke along with subarachnoid hemorrhage and intracerebral hemorrhage.
Ischemia causes changes in brain metabolism, decreased metabolic rate, and energy crises.
There are two types of ischaemia: focal ischemia, limited to a specific area of ​​the brain; and global ischemia, which covers a large area of ​​brain tissue.
The main symptoms involve impairment in vision, body movement, and speech. The causes of brain ischemia vary from sickle cell anemia to congenital heart defects. Symptoms of brain ischemia may include unconsciousness, blindness, coordination problems, and weakness in the body. Other effects that may arise due to ischemic brain are stroke, cardiorespiratory arrest, and irreversible brain damage.
Impaired blood flow to the brain for more than 10 seconds causes unconsciousness, and flow disturbances for more than a few minutes generally results in irreparable brain damage. In 1974, Hossmann and Zimmermann showed that ischaemia induced in the mammalian brain up to an hour may be at least partially recovered. Thus, the present invention increases the likelihood of intervention after brain ischemia before the damage becomes irreversible.
Video Brain ischemia
Classification
The broad term, "stroke" can be divided into three categories: brain ischemia, subarakhnoid hemorrhage and intracerebral hemorrhage. The brain of ischemia can be subdivided, by cause, into thrombotic, embolism, and hypoperfusion. Thrombotics and embolism are generally focal or multifocal, while hypoperfusion affects the brain globally.
Focal brain ischemia
Focal brain ischemia occurs when blood clots clog the cerebral vessels. Focal brain ischemia reduces blood flow to certain brain regions, increasing the risk of cell death to certain areas. Can be caused by thrombosis or embolism.
Global brain ischemia
Global brain ischemia occurs when blood flow to the brain is stopped or drastically reduced. This is generally caused by a heart attack. If the circulation is sufficiently restored in a short time, the symptoms may be temporary. However, if a significant amount of time passes before recovery, brain damage may be permanent. While reperfusion may be important to protect brain tissue as much as possible, it can also cause reperfusion injury. Reperfusion injuries are classified as damage that occurs after the restoration of blood supply to the ischemic tissues.
Maps Brain ischemia
Symptoms
Symptoms of brain ischemia reflect the anatomical region of the blood and lack of oxygen. Ischemia in arteries branched from the internal carotid artery can cause symptoms such as blindness in one eye, weakness of one arm or leg, or weakness on one side of the body. Ischemia in arteries that branch off from the vertebral arteries behind the brain can cause symptoms such as dizziness, vertigo, double vision, or weakness on both sides of the body. Other symptoms include speech impairment, slurred speech, and loss of coordination. The symptoms of brain ischemia range from mild to severe. Furthermore, symptoms may last from a few seconds to several minutes or extended periods of time. If the brain becomes damaged irreversibly and infarction occurs, symptoms may be permanent.
Similar to cerebral hypoxia, severe or prolonged brain ischemia will result in unconsciousness, brain damage or death, mediated by ischemic cascade.
Some cerebral ischemic events may cause subcortical ischemic depression, also known as vascular depression. This condition is most often seen in elderly depression patients. Slow-onset depression is increasingly seen as a distinct sub-type of depression, and can be detected with MRI.
Cause
Ischemic brain has been associated with various diseases or disorders. Individuals with sickle cell anemia, compressed blood vessels, ventricular tachycardia, plaque buildup in arteries, blood clots, very low blood pressure as a result of heart attacks, and congenital heart defects have a higher predisposition to brain ischemia compared to their healthy counterparts.
Sickle cell anemia can cause brain ischemia associated with irregularly shaped blood cells. Sickle-shaped blood cells clot more easily than normal blood cells, blocking blood flow to the brain.
Veins compression can also cause brain ischemia, by blocking the arteries that carry oxygen to the brain. Tumors are one of the causes of vascular compression.
Ventricular tachycardia is a series of irregular heartbeats that can cause the heart to completely die so that the cessation of oxygen flow. Furthermore, irregular heartbeat can result in the formation of blood clots, thus causing oxygen deprivation to all organs.
Blockage of the arteries due to plaque buildup can also cause ischemia. Even a small amount of plaque that builds up can lead to channel narrowing, causing the area to become more susceptible to blood clots. A large blood clot can also cause ischemia by blocking blood flow.
Heart attacks can also cause brain ischemia because of the correlation that exists between heart attack and low blood pressure. Very low blood pressure usually indicates inadequate tissue oxygenation. Untreated heart attacks can slow the flow of blood so that the blood begins to clot and prevent blood flow to the brain or other major organs. Very low blood pressure can also occur due to drug overdose and reaction to drugs. Therefore, brain ischemia can occur due to events other than a heart attack.
Congenital heart abnormalities can also cause brain ischemia due to lack of proper arterial and connection formation. People with congenital heart defects are also susceptible to blood clots.
Other pathological events that can cause ischemic brain include cardiorespiratory arrest, stroke, and irreversible severe brain damage.
More recently, Moyamoya's disease has also been identified as a potential cause for brain ischemia. Moyamoya's disease is a very rare cerebrovascular condition that limits blood circulation to the brain, consequently causing oxygen deprivation.
Pathophysiology
During ischemic brain, the brain can not perform aerobic metabolism due to loss of oxygen and substrate. The brain can not switch to anaerobic metabolism and, having no long-term energy stored, adenosine triphosphate (ATP) levels drop rapidly, close to zero in 4 minutes. In the absence of biochemical energy, cells begin to lose the ability to retain electrochemical gradients. Consequently, there is a large influx of calcium into the cytosol, the massive release of glutamate from synaptic vesicles, lipolysis, calpain activation, and the capture of protein synthesis. In addition, the removal of metabolic waste is slowed. Blood flow to the brain for ten seconds causes sudden loss of consciousness. Blood flow disturbances for twenty seconds result in the cessation of electrical activity. An area called penumbra can occur, in which neurons do not receive enough blood to communicate, but receive enough oxygenation to avoid cell death for a short time.
Treatment
Alteplase (tpa) is an effective drug for acute ischemic stroke. When administered within 3 hours, treatment with tpa significantly increased the likelihood of a favorable outcome compared to treatment with placebo.
The results of brain ischemia are influenced by the quality of subsequent supportive care. Systemic blood pressure (or slightly above) should be maintained so that cerebral blood flow is restored. Also, hypoxemia and hypercapnia should be avoided. Seizures can cause more damage; therefore, anticonvulsants should be prescribed and seizures should occur, aggressive care should be taken. Hyperglycemia should also be avoided during brain ischemia.
Management
When a person presents with ischemic events, the underlying cause treatment is essential for the prevention of subsequent episodes.
Anticoagulation with warfarin or heparin may be used if the patient has atrial fibrillation.
Operating procedures such as carotid endarterectomy and carotid installation may be performed if the patient has a significant amount of plaque in the carotid artery associated with local ischemic events.
Research
Therapeutic hypothermia has been attempted to improve post-brain ischemia results. This procedure is recommended to be useful based on post-heart attack effects. Evidence supporting the use of therapeutic hypothermia after brain ischemia, however, is limited.
The disease that is closely related to brain ischemia is brain hypoxia. Brain hypoxia is a condition in which there is a decrease in the supply of oxygen to the brain even in the presence of adequate blood flow. If hypoxia persists for long periods of time, coma, seizures, and even brain death may occur. Symptoms of brain hypoxia are similar to ischaemia and include inattention, poor judgment, memory loss, and decreased motor coordination. Potential causes of brain hypoxia are suffocation, carbon monoxide poisoning, severe anemia, and the use of drugs such as cocaine and other amphetamines. Other causes associated with brain hypoxia include drowning, choking, choking, cardiac arrest, head trauma, and complications during general anesthesia. Treatment strategies for brain hypoxia vary depending on the initial cause of injury, primary and/or secondary.
See also
- Mechanism of anoxic depolarization in the brain
- The watershed
References
Bibliography
- Veronika I. Skvortsova; Eugene I. Gusev; Skvortsova, Veronica I. (2003). Ischemic Brain . New York: Kluwer Academic/Plenum Publisher. ISBN: 0-306-47694-0. Ã ,
Further reading
- Chang, Steven; Doty, James; Skirboll, Stephen; Steinberg, Gary. Cerebral ischaemia. cgi.stanford.edu . Last URL accessed February 26, 2006.
- Ramirez, Robert; Gulli, Laith. Encyclopedia of Neurological Disorders: Hypoxia. health.enotes.com . Last URL accessed February 26, 2006. (PDF format)
External links
Source of the article : Wikipedia
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