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[Stereotactic brachytherapy for clival chordoma].

There has recently been interest in the use of high-dose radiation with methods such as radiosurgery and brachytherapy for skull base tumors. Brachytherapy is believed to be effective for clival chordomas, but technical difficulties exist in stereotactic insertion of catheters into the clivus. We assessed the usefulness following improvement of implantation techniques in three patients with clival chordomas. All tumors were larger than 50 mm in diameter. Removable iridium-192 sources were held in catheters which were implanted through a transnasal approach under general anesthesia using a CT-guided stereotactic system in one patient and a CRW stereotactic system adapted to a magnetic resonance imaging (MRI) scanner in 2 patients. The implantation array was designed based on results of stereotactic 3-D MRI scanning, and coordinates were calculated for stereotactic implantation through twist drill holes. These catheters were introduced through the nares and directed into the clival chordoma under endoscopic visualization and X-ray fluoroscopy. No complications such as CSF liquorrhea, hemorrhage or infection were observed. Brachytherapy with a total dose of 43.2-58.0 Gy at the tumor periphery was administered for 7 to 10 days, and serial follow-up imaging studies demonstrated reduction in tumor size in two patients and no tumor growth in the other. Our results suggested that stereotactic brachytherapy is potentially useful for the control of clival chordomas and that computer-guided transnasal stereotactic insertion enables implantation of catheters less invasively and more accurately than does X-ray fluoroscopic guidance alone.