SUBCORTICAL U-FIBERS LAYER PRESERVATION IN BRAIN EDEMA

The mechanism involved in the relative preservation of the subcorticaI U-fibers in the arcuate zone was studied in a post infarct edema afte r sagittal superior sinus occlusion. Superior sagittal sinus (SSS) of 36 mongrel cats were occluded by polymer injection. Immediatly before the occlusion Evans-blue (EB) was administered intravenously. The cats were killed 1, 2, 3, 6, 12, 24, 72 and 120 hours after sinus occlusio n. In 20 cats in which cortical veins were occluded, in addition to th e SSS, EB was extravasated. In 9 of these cats, which had moderate ede ma, EB-staining was present only in the cortex. In 11 cats with severe edema, massive EB extravasation was observed also in the white matter . The U-fiber layer was free of EB, suggesting that the extension of e dema was blocked by this zone. Our findings demonstrated that the U-fi bers act not only as a resistence against extension of edema from whit e to gray matter, but also in a reverse direction. The characteristics of the spread of brain edema is not yet completely understood; both a natomical and biochemical peculiarities form its basis. Different morp hological patterns in the astrocytic reaction as well as the U-fibres sector vascularization are important. To evaluate the role of each one of these factors in the preservation of subcortical U-fiber layer in brain edema further investigations should be done.