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| Ischemic Stroke |
Blood flow to the brain in ischemic stroke stops because atherosclerosis (cholesterol buildup in blood vessel walls) or a blood clot that has clogged the arteries to the brain. Blockage can occur along the arteries leading to the brain. For example, an atheroma (Fatty deposits) can form in the carotid artery, causing reduced blood flow. The situation is extremely serious because each carotid arteries normally supply blood to most of the brain.
Occurrence of resistance in blood flow to the brain will result in nerve cells and other cells in the impaired supply of oxygen and glucose. When the supply disruption lasted until beyond the tolerance of cells, cell death will occur. Meanwhile, when the blood flow can be repaired quickly, damage can be minimized.
Pathophysiology of Ischemic Stroke
The mechanism of ischemic stroke can be divided into two, namely thrombosis or embolism . An estimated two-thirds of ischemic stroke caused by thrombosis, and one-third due to embolim. However, to distinguish clinically, the pathogenesis of which occurred in the case of ischemic stroke is not easy, and often can not be distinguished at all.
Thrombosis can cause ischemic stroke, because thrombosis in the blood vessels will result in occlusion (closing or closed state of motion) cerebral artery, particularly the internal carotid artery, middle cerebral artery, or basilar artery. But the truth can also occur in smaller arteries, the arteries such as penetrating lacunar area and can also occur in the venous and sinus venosus cerebralis.
Stroke due to thrombosis is usually preceded by an attack TIA (transient ischemic attack). Symptoms that occur are usually similar to the preceding TIA, because the area of impaired blood flow is the same brain area. TIA is a neurological deficits that occur in a very short period of time ranging from 5-20 minutes or can be up to several hours, and then underwent a complete refurbishment. Although it does not cause any complaints after the attack, the TIA is clearly a matter that needs to be taken seriously, because about one-third of patients with TIA will have a stroke within 5 years. In other circumstances, neurologic deficits that have occurred over the past 24 hours or more may also experience a complete recovery or nearly complete in a few days. This situation is often called a minor stroke or reversible ischemic neurological deficit (Rind).
Embolism causing stroke, when an artery in the brain occluded by a thrombus originating from the heart, aortic arch, or other large arteries breaks off and get into the bloodstream in the veins of the brain. Embolism in the posterior circulation is generally about the middle cerebral artery or branches because 85% hemispheric blood flow derived from it. Emboli in the posterior circulation usually occurs at the apex of the basilar artery or the posterior cerebral artery.
Stroke due to embolism in which the characteristic neurological deficits directly reach the maximum level since the beginning (onset) symptoms appear. If attacks occur due to TIA before stroke embolism, symptoms usually varies obtained. This happens because the TIA precedes ischemic stroke due to embolism, hemorrhage typically affects different areas, from time to time.
Fatty deposits can also be detached from the walls of the arteries and blood flow in the arteries which then clog smaller. Carotid and vertebral arteries and their branches could also be clogged by a blood clot from elsewhere, such as of the heart or a valve. This kind of stroke called cerebral embolism, which most often occurs in patients who had undergone cardiac surgery and patients with heart valve abnormalities or arrhythmias (especially atrial fibrillation). Embolism of lipid formed when lipid from a ruptured spinal released into the bloodstream and eventually joined in an artery.
RELATED ARTICLES
• Post-Acute Phase Therapy of Stroke
MEDICAL BOOKS ABOUT STROKE
Source
1. Picture: http://www.mayoclinic.com/health/medical/IM00074
1. Picture: http://www.mayoclinic.com/health/medical/IM00074
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