Evolution of venous cerebral infarction and brain edema--an experimental study of sagittal sinus obstruction

Superior sagittal sinus with/without neighboring venous system of 36 mongrel cats were occluded by cyanoacrylate polymer after i.v. administration of Evans-blue (EB). Thereafter, the cats were sacrificed 1, 3, 6, 12, 24, 72 or 120 hours after sinus-vein occlusion. According to the degree of occluded region, the cats were divided into two groups; group A (GA) and B (GB). GA showed only superior sagittal sinus occlusion, while many cortical veins were also occluded in GB. No EB nor histological changes were found in 13 cats of GA and 4 sham operated cats, while EB distribution was observed in all 20 cats of GB. The other 3 cats of GA showed a little EB in gyrus lateralis. EB distribution of GB were divided into two types. Type 1 showed EB mainly in the cortical gray matter, while type 2 showed massive EB extravasation in the white matter as well. Edematous changes with gliosis in its resolution phase, were observed in type 1. In addition, EB free zone was formed along with U-fiber zone (cortico-medullary junction) in the cats of later phase (72 hours after occlusion). The findings of EB extension in the type 1 means the existence of blockage against edema evolution from cortex toward subcortical white matter. The cats of type 2 showed fulminant hemorrhagic changes which appeared depend on time interval. Although occurrence of pathological changes were rather earlier than that of cases of clinical cerebral sinus thrombosis, this pathological findings demonstrated the typical character of venous hemorrhagic infarction. In this paper, the similarity and difference between this model and clinical case of sinus-vein thrombosis were discussed. And the possible function of the U-fiber zone in the corticomedullary junction against edema evolution was suggested.