Application of CO2 laser in the Neurosurgical Microscopic Operation

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The effect of puls-wave form CO2 laser was compared with that of continuous wave form using the 60z of Nihon-Infrared Industry Company. The tissue change by the puls wave form CO2 laser exposure was three times more than that of continous wave form CO2 laser if the power is the same in both lasers. The breakdown of the BBB was the greatest 24 hours after the exposure, but was still repaired one week thereafter.The lasers in the next study were pulse wave form CO2 and YAG lasers, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. The efficiency of laser exposure for hemostasis was greatest in Nd:YAG laser alone followed by combined CO2 and Nd:YAG laser and least in CO2 laser alone. In the combination of CO2 and Nd:YAG lasers, the more the power of Nd:YAG laser used, the less the hemorhage occurred. The size of the lesion by the combined laser exposure was greater than that of CO2 or Nd:YAG laser alone. Nd:YAG laser contributed to increase the diameter, and the CO2 laser the depth of the lesion.Effect of Nd:YAG and CO2 laser beam on micro-vasculature was examined in experimental animal. Soft x-ray microangiography and histological examination of brain after Nd:YAG laser exposure revealed broad avascular or oligovascular zone din the irradiated and the surrounding edematous tissue, in which the survived vessels showed narrowing and tapering without significant leak of blood. These findings seemed to correspond to high hemostatic capability of Nd:YAG laser. Vascular structure in the surrounding edematous layer after CO2 laser exposure, on the other hand, was not so significantly affected by exposure as in Nd:YAG laser, and congested and sometimes reptured vessels were found close to the central vaporized tissue defect in the coagulation layer which might cause postexposure hemorrhage.