Brainstem navigation with Intraoperative anatomical landmarks registration: Technical note

Abstract

Background. Cranial navigation in brainstem surgery can be especially challenging due to registration method limitation and complex anatomic orientation. Surface anatomical landmarks are not available and fiducial registration usually needs image acquisition at the day of surgery. Intraoperative registration is often used during spinal navigation with safe and reliable accuracy. We present our technique of navigation for brainstem lesions surgeries using intraoperative anatomical landmarks for registration. Methods. From March 2008 to November 2018, 38 patients underwent suboccipital midline approaches for removal of brainstem and/or fourth ventricle lesions with frameless navigation. We performed CT scan and MRI sequence with gadolinium enhancement for each patient a day before the operation. The CT/MRI image fusion and surgical planning was performed in Brainlab® workstation. Navigation registration was performed after skin incision and external skull base anatomical landmarks exposure. Results. The anatomical landmarks used for registration was based on bone structures visible on CT images. The accuracy flaw was insignificant for brainstem navigation, especially for the roof and lateral limits of the fourth ventricle. The image-guided system was very useful for tumor localization and removal in all cases. Conclusions. Intraoperative anatomical landmarks registration is a fast and safe method for brainstem navigation. The brainstem is a fixed encephalic structure and the shifting is insignificant. Anatomical landmarks (inion, foramen magnum, nucal lines, C1 posterior arc) and a careful surgical planning are necessary in order to avoid accuracy lost.