So a considerable amount of work on the cerebral edema has been done by numerous investigators that it is difficult to summarize the research works of cerebral edema on this paper. Cerebral edema is a well recognized clinical entity. It was also quite obvious around many cerebral tumors and injured brains of the post-mortem materials. Further, in 1937, Stewart-Wallace considered that the fluid increase of the cerebral edema was in the intercellular or interstitial spaces. This was accepted by histologist using the light microscope and biochemists for the next two decades: Since 1957 electron; microscope has been used to study, .the concept of cerebral edema has been changed.
So the author selected and introduced´ the following experimental studies and their conclusions from , a number of different clinical and experimental research works df cerebral edema that have been carried out since 1957.
1) Cold induced cerebral edema.
2) Experimental cerebral swelling produced by. supratentorial extradural compression (implanted balloons).
3) Triethyltin-induced cerebral edema.
4) Cerebral edema due to implantation of foregin substances.
5) Cerebral edema associated with experimental intracerebral tumors.
6) Experimental ischemic brain swelling and experimental intracranial hypertension due to vascular blockade.
7) Ouabein-induced cerebral edema.
8) Serotonin-induced cerebral edema.
9) Cerebral edema due to radiofrequency lesion.
10) The effect of laser irradiation.
By these experimental cerebral edema numerous conclusions were reported, But the important results were as follows:
1) In the cortex there is enlargement of astrocytes.
2) Axonal and myeline changes occur.
3) Ultrastructural studies indicate that edema was entirely intracellular.
4) Basically cerebral edema is an extracellular phenomenon of the white matter accompanied by marked swelling of the astrocytes.
5) An increase in water and- sodium and decrease in potassium content of white matter, resulting in a sharp rise of Na:K ratio are evident.
6) Radioactive amino acid incorporation into. protein of edematous brain is increased.
7) The depressed respiratory control, depressed P:O ratio and accelerated state 4 respiration are present.
Moreover, it has become apparent that these are some disadvantages in the experimentally induced cerebral edema. It may not involve the entire brain uniformly: different agents produce different types of edema; patterns are subject to variations of animal species and cerebral topography; the extent of damage is not controllable and reproducible; consistency of damage is uncertain. no all experimental edema are artificial and not completely analogous to those occuring in human pathology.
Nonetheless, cold ´induceld edema and extradural compression method can be considered as a prototype of traumatic brain swelling.
And the experimental intracerebral tumros can be exact countparts in human pathology also. The laser irradiation and radiofrequency lesion can produce standardized lesion and edema, further they will be appreciable to study the efficacy of various agents in reducing intracranial damage and edema.
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