The causes of ischemic stroke is most often either thrombosis or embolism it - blocked. Thrombosis usually develops in the vessel lumen which is already narrowed by atherosclerosis. The most frequent source of embolism - the heart. Such emboli may occur during atrial fibrillation, heart failure or myocardial infarction, since these states are formed in the cavity of the heart clots that through the blood can get into the carotid artery. Less commonly, the source of emboli may be ulcerated plaques in the aortic arch. Other causes of ischemic stroke are rare.
For ischemic stroke there is a deficiency of blood supply of certain parts of the brain. The area of damage depends on the caliber and type of the affected vessel. As a result of cessation of blood supply to the developing cerebral infarction. Necrosis, ie, necrosis of brain cells. Depending on what part of the brain hit, there are certain symptoms of stroke. Ischemic stroke usually develops within a few seconds or minutes (sometimes for hours or days) and appears to motor, speech, and (or) other focal neurologic disturbances. Movement disorders are in the occurrence of paralysis and paresis ("incomplete paralysis"), limb, or half of the face, tongue. Marked impairment - strabismus, double vision, decreased visual fields.
Infarcts of the cerebellum. At an early stage of cerebellar infarction usually manifests dizziness, nausea, vomiting, nystagmus (special movement of the eyeballs) and ataxia (movement disorder, manifested disorder of coordination), detectable with the finger-nose and heel-knee tests. After 1-3 days, can develop symptoms of brainstem compression due to swelling of the cerebellum - paralysis of the eye, damage to the trigeminal and facial nerves. Perhaps the rapid development of coma and death. In cerebellar infarcts within the first few days should be carefully monitored, since compression of the trunk can be prevented by surgical decompression of the posterior cranial fossa.
Another type of ischemic stroke - lacunar infarct. Thus there is a special type of thickening of the small arteries of the brain. Most often it is observed in hypertension and diabetes. Blockage of these vessels leads to the development of small deep infarcts located (lacunar infarcts), on the site which usually form cysts. This kind of heart attacks is often asymptomatic, but may occur such clinical syndromes as "pure motor stroke," "pure sensory stroke" syndrome, "dysarthria / clumsy hand", ipsilateral ataxia with paresis of legs, "pure motor hemiparesis" to gaze palsy and etc.