2026 Proffered Presentations
S176: IMPROVING INACCURACIES IN AUGMENTED REALITY NEURONAVIGATION DURING ANTERIOR PETROSECTOMY BY RECALIBRATING USING FIXED BONY LANDMARKS
Hayes H Patrick, MD; Arhum Naeem; Walter Jean, MD; George Washington University
Background: The anterior petrosal approach from Kawase (1985) is an expansion on the middle fossa approach in order to provide an extradural opening to the posterior fossa.1 The visualization of anatomical landmarks is essential for identifying the Kawase quadrilateral, which lies between the greater superior petrosal nerve, lateral border of the V3 cranial nerve, superior petrosal sinus, and anteromedial border of the arcuate eminence.2 Despite not being fully adopted into routine practice, Augmented Reality Neuronavigation (ARN) has been on the rise in recent years.3,5 It’s utility in the operating room spans from operative target location, trajectory guidance, and education for trainees. However, a contributing factor to its restricted use is intraoperative inaccuracies, with current literature reporting a target registration error of 2.5 mm. In an anterior petrosectomy case where drilling is occurring between the internal acoustic canal and the internal carotid artery, that registration error is unacceptably high. This suggests the need for improvement in critical intracranial areas.4 A promising method for addressing ARN inaccuracies is the use of bony landmarks for recalibration. Bopp (2022) utilized this method by leveraging surface level landmarks such as the craniotomy boundaries or burrholes for correcting errors.6 We demonstrate the use of the arcuate eminence as an intracranial bony landmark with close proximity to the operative target, to rectify inaccuracies in ARN during anterior petrosectomy procedures.
Methods: Three patients underwent anterior petrosectomies using a combination of virtual and augmented reality. The illustrative case (Figure 1) shows a small left sided intracanilicular vestribular schwannoma causing asymmetric hearing loss. Preoperative 3D rendering of the CT Angiogram, high-resolution CT temporal bone and MRI was used to illustrate the anatomic relationships between the arcuate eminence, semicircular canals, cochlea, and the pathology. Using the known barriers of the Kawase quadrilateral, a preoperative rendering of the safe drilling area in the petrous apex is shown (Figure 2). Intra-operatively, ARN inaccuracies are seen prior to incision, during the craniotomy, and after the extradural exposure of the middle fossa floor. Using the arcuate eminence as a fixed intracranial landmark with close proximity to the operative target, the ARN is recalibrated (Figure 3). This moves the rendered safe drilling area into an accurate anatomic location, which can be used to safely and efficiently perform the anterior petrosectomy.
Results: The pre-rendered safe drilling area was projected through the microscope in order to illustrate its anatomic relationship with the surrounding structures and confirm its accuracy (Figure 4). In this series of three patients, the technique of recalibrating the ARN using the arcuate eminence was successfully achieved while performing the petrosectomy.
Conclusions: Inaccuracies in Augmented Reality Neuronavigation can be corrected by using fixed bony landmarks if they are rendered during preoperative planning. Using the arcuate eminence as the landmark during an anterior petrosectomy, ARN can be used to safely and efficiently perform this complex skull base approach. ARN can only be reliable when it is calibrated using known anatomy, and caution should be used when using potentially inaccurate technology in the operative room.
