Cortical vein occlusion by photochemical thrombosis

Two adjacent superficial cortical veins connecting into the superior sagittal sinus were occluded using Rose Bengal dye (Sigma Chemical Co., St. Louis, MO, USA) in combination with fiberoptic illumination (100-W mercury lamp [6,500–7,500 lx, 540 nm]) connected to a 200-μm fiber. Only animals which presented similar anatomy (i.e., two prominent adjacent cortical veins connecting into the superior sagittal sinus) were used in this study. The diameter of occluded veins was approximately 80–100 μm. Rose Bengal at the dose of 50 mg/kg was slowly injected intra¬venously; target veins were then selectively illuminated using a micromanipulator-assisted fiber-optic light guide with care taken to avoid illumination of nearby tissue and other blood vessels. Target veins were illuminated for 10 minutes. Prior to the illumination of the second target vein, half of the initial Rose Bengal dosage was additionally administered intravenously before the illumination was undertaken. Occlusion of veins was confirmed with the laser Doppler system detecting acutely decreased blood flow at the site of the veins and its surrounding tissues.