To examine the cerebral blood flow changes by laser exposure, we have measured them at the adjacent site using laser Doppler flow meter. Japanese white rabbits were anesthetized with intravenous pentobarbital and bilateral parieto-occipital craniotomies were made and the underneath dura were opened to expose the cerebral cortex. Coaxial laser of Nd:YAG and CO2lasers were exposed on each side of the cerebral cortex. For the control, bipolar coagulator was applied on the cerebral cortex for 1 second. A probe of laser Doppler flow meter was placed on the brain surface and regional cerebral blood flow, blood velocity and blood volume were recorded.
At the site 2mm distant from the exposure area, some increase of cerebral blood flow and blood velocity was observed. It continued about 2 to 5 minutes and returned to the control value. At the site more than 10mm distant, slight or no detectable changes were observed. Moreover, coagulation by a bipolar coagulator brought about similar effects. From these results, it is concluded that the disturbance in the epicerebral microcirculation after laser exposure was localized, temporary and not specific for laser exposure.
