10222- STMO-16 THE FENCE-POST METHOD WITH BONY SURFACE MATCHING REGISTRATION.

Neuronavigation has become an indispensable system for brain tumor surgery, and the fence-post method is useful for removal of intramedullary tumors. However, accurate registration is difficult in the lateral or prone position, and the fence-post method is hesitated. Skull registration is considered to be highly accurate, and we have found a method to perform skull registration with a limited amount of exposed skull. We have found a method to perform skull registration with a limited number of exposed skulls, and we report the results of the fence-post method using this method. from May 2023 to August 2024, patients who underwent the fence-post method in the lateral or supine position were included in the study. The navigation system was a StealthStation S8 (Medtronic), and skull registration was performed from CT. If impossible, a skull section was made in the navigation system according to the surgical site, and registration was performed using the skull localized in the surgical field. We encluded 11 cases, five with glioma and six with metastatic brain tumors. Two cases required a craniotomy larger than 10 cm for temporal lobectomy, and in these cases, skull registration was possible without any special modification. In the other 9 cases, the craniotomy was less than 10 cm, and normal skull registration was not possible, but the skull was limited to the operative field, and the fence-post technique was performed. Three cases of glioma were subtotal, and the others were total resections without complications. If the skull is localized to the operative field and sectioned within the navigation system, skull-based registration will be possible, improving the accuracy of the fence-post method and contributing to the safety of the surgery.