What is the mechanism?

First of all, ischemic stroke has three different mechanism:

1. Thrombosis

It may occur in large arteries like vertebral trunk or carotid trunk. It is expressed by a formation of atherosclerotic plaques, then the rupture of the plaque releases chemicals that stimulate clot formation (thrombosis). Blood flow stopped and there is death of brain tissue.

It might occur in small arteries in the central portion of the brain (lacunar infarct) and affect the basal ganglia and the pons in the brain stem. One of the main risk factors is the hypertension. This is due to a lipohyalinosis damage in wall of the arteries which is going to compress the blood flow in the vessels.

• Embolism

That define itself by an obstruction arising from elsewhere.

The embolism can come about by three different way:

-Reduced ejection fraction, embolization and stroke: a reduced ejection fraction results in stasis of blood at apex of ventricle. Blood stasis results in thrombus formation at the apex. Thrombus breaks up and is ejected into the aorta. Clot lodge in the right middle cerebral artery of the brain obstructing multiple branches of the medial cerebral arteria and causing a stroke.

-Atrial fibrillation, embolization and stroke: the left ventricle continues to draw blood though the left atrium but the blood movement in the appendage much reduced (stasis). The blood stasis results in formation of clot in atrial appendage. The thrombus breaks up and embolizes to the brain.

-Endocarditis and embolization to the brain (sceptic emboli): occur with bacterial infection in the bloodstream. The vegetation may detach from the valve leaflets causing obstruction to blood flow and stroke travel to the brain, blocking blood flow causing areas of ischemia with low oxygen flow.

• Global loss of blood flow

It may happen by hemorrhagic shock, cardiac arrhythmias, septicemia, narcotics overdose in the watersheld. The watersheld is characterized by the inner and outer flows of the blood brain meet in the “watersheld” area. Narcotic overdose causes prolonged low blood pressure (hypotension) with loss of blood flow to watersheld area and brain tissue death.

Then, hemorrhagic stroke has two different mechanism:

         It can show up by intracerebral (risk factors: hypertension, trauma, bleeding disorder, vascular malformation, amyloid angiopathy, drug abuse) or subarachnoid (risk factors: smoking, alcohol, hypertension, genetic, sympathomemetics, estrogen deficiency, antocoagulation, statin drugs) way.