[The use of twist drill craniostomy in stereotactic surgery for brain tumors].

A twist drill craniostomy is a rapid and relatively simple technique for perforating the skull in order to gain access to the epidural and subdural spaces and the brain. Fifty-eight patients underwent 173 twist drill craniostomies in the stereotactic procedures for the diagnosis and the treatment of brain tumors (brain tumor biopsy, implanting radioactive sources and placement of the catheters for navigation surgery) from September, 1992, through to May, 1995, at our institute. The technique was compared with standard burr hole craniostomy used in 42 patients with brain tumor. In the twist drill craniostomy, the scalp was penetrated directly by hand twist drill (2.7 mm in diameter) and scalp bleeding was able to be be controlled by injecting local anesthetic with epinephrine subcutaneously. The safety stop on the drill was set in advance based on the expected thickness of the skull at its penetration point to provide control of penetration depth as it passed through the skull hole and dura. A hole in the skull was made as the drill was advanced until a change in resistance indicated that the inner table of the skull had been penetrated and the dura lacerated. The cannula with stylet was then inserted through the guide tube to assure the penetration of the skull and dura. As the cannula penetrated the dura, a loss of resistance was noted as it proceeded through the dura toward the pial surface, The time needed in this procedure was less than 3 minutes. Associated with this procedure, there were no complications such as bleeding, or infection in 173 twist drill craniostomies in the 58 patients. Our experience with this procedure proved it to be simple, efficient, safe and superior to conventional burr hole craniostomy.