Abstract

FONTANA, Horacio et al. La circulación cerebral en condiciones normales y patológicas: Parte I: hipertensión endocraneana e isquemia secundaria. Rev. argent. neurocir. [online]. 2007, vol.21, n.1. ISSN 1850-1532.

The ischemic lesions in dead patients from severe head injury are distributed predominantly in central territories, and could be secondary to distortion and occlussion of perforant vessels during encephalic desplacement and herniation. Some central lesions could also be primary. The ischemic lesions secondary to diminution of CPP during intracranial hipertension are less frequent than those due to vascular distortion. Thus, it seems physiopathologically more important desplacement and herniation than CPP. A cerebral infarct occurs when CBF is inadequate to support the basic metabolic needs or is lower than 20 ml/ 100 gm/ min., corresponding with a CPP between 35 - 40 mm Hg. The while during which the cell rests viable is not well known. Within traumatic foci, CPP could be lower than mesured by general methods, but ischemia sould not obligatorily follow it. The metabolic needs of those areas could be lowered because of primary cellular necrosis. The oxidative metabolism of glucose could be impaired during ischemia, producing accumulation of deleterious acid metabolites to the neuron. It is possible that "plateau waves" be pathogenic not by itself, but by concomitant structural causes. Nonrhytmic oscilations of volume are normal probably in all organs. Oscillations in volume of the same lesion could be another cause of plateau waves. Decompressive craniectomy could be forced by an exaggerated CPP therapy. CPP over 50 mmHg could produce edema and hemorhage in contused brain in vaso paralysis. Early decompressive craniectomy is indicated in cases with reperfusion edema. The cerebral veins does'nt collapse during intracranial hypertension. The composition of blood in one sigmoid sinus can be different from that of the other side in pathological cases, and is similar in normal subjects. Study of the flow or chemical composition of blood in the sinus rectus could be helpful for the prognosis and therapeutics in patients with acute cerebral disease. Changes in flow velocity at the jugular bulbs coud give an approximation about global CBF changes.

Keywords : Cerebral circulation; Perfusion pressure; Intracranial hypertension.

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