Experimental study on cerebral venous circulatory disturbance

A new experimental model of cerebral venous occlusion was developed and the cerebral hemodynamics and water content using this model were studied. An anatomical study of the cerebral venous system using methacyrl resin showed that the venous system was composed of superficial and deep veins. The superficial veins drained into the superior sagittal sinus (SSS). The SSS was connected to internal and external jugular veins via the transverse sinuses and diploic veins (DV), respectively. The cats were divided into three groups on the basis of the occlusion sites as follows ; Group I : SSS occlusion, Group II : DV occlusion, Group III : occlusion of both the SSS and DV. Intracranial pressure (ICP) and cerebral blood volume (CBV, photoelectric method) were monitored continuously. Local cerebral blood flow (1-CBF) and water content were measured by hydrogen clearance and gravimetric methods, respectively. Somatosensory evoked potential (SEP) was also recorded. Evans blue was injected intravenously to evaluate blood brain barrier permeability. There were no siginificant changes in ICP, 1-CBF or N1 latency of SEP after the occlusioon in Group I or II. However, in Group III, 1-CBF decreased significantly 2 hours after the occlusion as ICP increased gradually. N1 latency of SEP was prolonged and water content increased significantly. CBV increased immediately after the occlusion. There was no extravasated Evans blue. The increase in CBV and water content during sinus occlusion appeared to have led to intracranial hypertension and decrease of 1-CBF, which resulted in neural dysfunction. The brain edema in this model seemed to be hydrostatic edema or cytotoxic edema