The embolism is produced a time that one has broken or one pieces trombo bigger if trombo separates of one mural, being able to happen in places as the heart or a proximal artery and if it lodges distalmente in a point where the diameter of the vase has the diminished size, of this I form trombo circulating more will not obtain to cross arterial light (GOLDMAN; AUSIELLO, 2005). A time that has interruption of the sanguineous flow in a portion of the brain or the reduction of the same, the survival of this fabric at risk will depend on some factors modificadores as the collateral availability of circulation, the time of the isquemia and the rapidity of the reduction of the flow. Factors these that go to determine the localization of the injury, its size and consequently, clinical deficiency (KUMAR; ABBAS; FAUSTO, 2005). One knows that two main types of decurrent acute ischemic injury of the reduction of the sanguineous flow in the fabric exist cerebral: Global cerebral Isquemia (hipxica ischemic encefalopatia/) that it occurs when has a generalized reduction of the cerebral perfuso, as in the cardiac arrest, has shocked and severe hipotenso. Focal cerebral Isquemia that if follows to the reduction or the interruption of the sanguineous flow for a located area of the brain because of the illness of the great vase (as well as the trombtica or emblica arterial occlusion, frequent in the scene of aterosclerose) or to the illness of the small vases (as well as the vasculite or the secondary occlusion to the arteriosclerticas injuries sights in the hipertenso) (KUMAR; ABBAS; FAUSTO, 2005, P. 1426). The cause enters most common and patognese of the ischemic BIRD is aterosclerose, embolism of cardiac origin that can be trombos walls, cardiopathy to valvar, arrhythmias and paradoxical embolism. Goldman and Cuisiello (2005) they agree that, it can be standed out that the riot most common to lead to a BIRD is the formation of ateromas what consequentemente of the beginning to one aterosclerose.