Experimental study of single and combined coaxial exposure by high-peaked pulse wave CO2 and Nd:YAG laser on the brain: effect on the brain microvasculature in the subacute stage

The effect of single or combined coaxial exposure by Nd: YAG and CO2 (pulse wave) laser on the brain at the subacute stage was examined in experimental animals. Soft X-ray microangiography and histological examination of the brain were performed 48 hours after laser exposure. The lasers in this study were pulse wave form CO2 of 2, 4 and 8 watts and YAG lasers of 10, 20 and 40 watts, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. Japanese white rabbits were anesthetized with pentobarbital. Bilateral fronto-parietal craniectomy were made, and the dura was removed. After intravenous injection of Evans blue, the lasers were employed to the cerebral cortex using a micromanipulator attached to the operation microscope. The spot size was 0.7 mm in diameter for CO2 laser and 1.2 mm for Nd: YAG laser. Forty-eight hours after exposure, microangiography was performed and brains were prepared for the histological examination. Histological examination and microangiogram of the brain after CO2 laser exposure revealed semilunar avascular area in the edematous layer surrounded with dilated vessels. Histological examination and microangiogram of the brain after Nd: YAG laser exposure revealed broad avascular or oligovascular zones in the surrounding edematous tissue, in which the surviving vessels were narrowed. Edematous zones were also shown in the subcortical portion. The histological examination and microangiogram after combined coaxial exposure of CO2 and Nd: YAG lasers revealed triangular avascular or oligovascular zones in the edematous tissue, in which the surviving vessels were narrowed.(ABSTRACT TRUNCATED AT 250 WORDS)