Advance in laser neurosurgery by introduction of the Nd-YAG laser

Abstract

Experimental and clinical investigations were made to determine the suitability of the Nd-YAG laser in neurosurgical operations. The vaporization effect of the Nd-YAG laser coagulator (Molectron 8000, Medilas YAG) was experimentally examined using various materials. When boiled fish paste and a human skull were irradiated at a distance of 2 mm, vaporization occurred at the energy level of 70 watts, 1 sec. and 80 watts, 1 sec., respectively. At an energy level of 50 watts, 5 sec., rabbit livers was vaporized to the depth of 1 mm and kidney to a depth of 2.3 mm. From these experiments, the vaporization effect of the Nd-YAG laser proved adequate for clinical use. Using a Nd-YAG laser coagulator, 38 brain tumors were removed; they consisted of 19 pituitary adenomas, 10 meningiomas, 3 gliomas, 1 multiple myeloma, 1 fibrous dysplasia, 1 arteriovenous malformation, and 2 other brain tumors. The Nd-YAG laser had a greater hemostatic effect than the CO2 laser and it appeared suitable for highly vascular tumors. Since the laser beam of the Nd-YAG laser was transmitted by a flexible quartz fiber, it could be freely moved under the operative microscope. Thus, coagulation and hemostasis of a specific target site could be performed with ease making the laser highly suitable for the removal of deep seated tumors. In the transsphenoidal approach, the Nd-YAG laser permitted easy opening of the sella and sphenoid, even in the conchal type and presellar type sphenoid. Thus, with its strong hemostatic effect and flexible quartz fiber, the Nd-YAG laser has wide application in microneurosurgery especially with regard to easy removal of brain tumors.