Cerebral blood flow alterations in a rat model of cerebral sinus thrombosis.

Abstract

Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats. Thrombosis was induced by slow injection of kaolin-cephalin suspension after frontal and caudal ligation of the sagittal sinus in rats. Local cerebral blood flow was measured by laser Doppler flowmetry and correlated with parenchymal damage found 24 hours after induction of thrombosis. Local cerebral blood flow 1 hour after sinus occlusion and induction of thrombosis had decreased to 60.92 +/- 29.05% (p < 0.01); however, there was a large variability among individual animals. Only five of 12 rats showed histological damage and intracerebral hemorrhages 24 hours after induction of thrombosis. A subgroup analysis revealed that parenchymal damage occurred in concurrence with reduced blood flow values after sinus ligation and injection of the thrombogenic material. Sinus thrombosis alone, without alteration of blood flow, did not cause tissue necrosis. The data support the contention that sinus vein thrombosis evolves gradually, with major symptoms occurring only if the thrombus expands from the sinus into bridging and cortical veins. Collateral venous outflow pathways are thereby occluded, and local blood flow may become reduced to and below the ischemic threshold.

Compromise of Brain Tissue Caused by Cortical Venous Reflux of Intracranial Dural Arteriovenous Fistulas

“…10 Alternatively, previous experimental studies showed that retrograde venous pressure might counteract capillary perfusion pressure to decrease cerebral blood flow, and thus cause arterial ischemia resulting in cellular or cytotoxic edema. 12,21 Previous experimental and clinical diffusion-weight imaging studies of cerebral venous thrombosis have shown that ADC value was decreased, 12,22,23 normal, 23 increased, 24 or heterogeneous. 25,26 The ADC values decreased by 56% at 30 minutes after experimental cerebral venous thrombosis, and secondary increases in ADC subsequently developed in a rat model.…”

Diffusion-Weighted Magnetic Resonance Imaging in a Case of Cerebral Venous Thrombosis

“…21 However, venous ischemia also has specific characteristics, such as an early bloodbrain barrier disruption and an increase of the net capillary filtration, that may result in early vasogenic edema. 19,24 In our patient, the contrast between slight DWI abnormalities and marked FLAIR abnormalities may reflect prominent and early vasogenic edema associated with mild cytotoxic edema.…”

Laser-Doppler Scanning of Local Cerebral Blood Flow and Reserve Capacity and Testing of Motor and Memory Functions in a Chronic 2-Vessel Occlusion Model in Rats

“…13,22,23 The analysis of flow observation frequency histograms allows discrimination of the different effects of acetazolamide on microcirculation and on larger cortical vessels. A detailed correlation of anatomic structures and lCBF findings (S. Kroppenstedt, MD, unpublished data, 1997) shows that the most pronounced flow increase occurs in regions with a flow Ͻ60 LDU (microcirculation), while the flow in the vicinity of larger vessels remains largely unaffected.…”