Mismatch between Augmented Reality Navigation Images and Actual Location of a Cauda Equina Tumor : A Case Report

Background : Augmented reality navigation is the one of the navigation technologies that allows computer-generated virtual images to be projected onto a real-world environment. Augmented reality navigation can be used in spinal tumor surgery. However, it is unknown if there are any pitfalls when using this technique. Case presentation : The patient in this report underwent complete resection of a cauda equina tumor at the L2–L3 level using microscope-based augmented reality navigation. Although the registration error of navigation was < 1 mm, we found a discrepancy between the augmented reality navigation images and the actual location of the tumor, which we have called “navigation mismatch”. This mismatch, which was caused by the mobility of the spinal tumor in the dura mater, seems to be one of the pitfalls of augmented reality navigation for spinal tumors. Conclusions : Combined use of intraoperative ultrasound and augmented reality navigation seems advisable in such cases.