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Mastoidectomy involves drilling the temporal bone while avoiding the facial nerve, semicircular canals, sigmoid sinus, and tegmen. Optical topographic imaging (OTI) is a novel registration technique that allows rapid registration with minimal navigational error. To date, no studies have examined the use of OTI in skull-base procedures.In this cadaveric study, 8 mastoidectomies were performed in 2 groups-4 free-hand (FH) and 4 OTI-assisted mastoidectomies. Registration accuracy for OTI navigation was quantified with root mean square (RMS) and target registration error (TRE). Procedural time, percent of mastoid resected, and the proximity of the mastoidectomy cavity to critical structures were determined.The average RMS and TRE associated with OTI-based registration were 1.44 mm (±0.83 mm) and 2.17 mm (±0.89 mm), respectively. The volume removed, expressed as a percentage of the total mastoid volume, was 37.5% (±10.2%) versus 31.2% (±2.3%), P = 0.31, for FH and OTI-assisted mastoidectomy. There were no statistically significant differences between FH and OTI-assisted mastoidectomies with respect to proximity to critical structures or procedural time.This work is the first examining the application of OTI neuronavigation in lateral skull-base procedures. This pilot study revealed the RMS and TRE for OTI-based navigation in the lateral skull base are 1.44 mm (±0.83 mm) and 2.17 mm (±0.89 mm), respectively. This pilot study demonstrates that an OTI-based system is sufficiently accurate and may address barriers to widespread adoption of navigation for lateral skull-base procedures.

Background: Robotics is currently being adopted across the spectrum of neurosurgery from deep brain stimulation to spine surgery instrumentation. Mastoidectomy is a cognitively demanding procedure that involves careful removal of bone around the critical structures of the temporal bone. Herein, we report a pilot study that serves as a proof of concept for real-time, multiparameter recording during mastoidectomy. Methods: This pilot study involved the iterative development of a platform for the real time recording of video, 3D position, velocity, acceleration, and force data during the performance of mastoidectomy using cadaveric specimens. Results: Across all 8 replicates, the average distance traveled by the drill tip in the x, y, and z axes was 39.88 mm (±11.98 mm), 38.52 mm (±8.24 mm), 31.40 mm (±7.89 mm), respectively. The overall average ranges for velocity and acceleration of the drill tip in the x axis were 412.81 mm/s (±91.12 mm/s) and 6383.05 mm/s2 (±941.05 mm/s2). The range of forces recorded was 8.52 N (±2.90 N), 40.94 N (±9.81 N), and 35.42 N (±11.06 N) in the x-, y-, and z-axis, respectively. Conclusions: This study represents a proof-of-concept that the mechanical parameters associated with surgeon-performed mastoidectomy can be recorded in real-time. This represents a crucial step in understanding the human drilling process which incorporates visual and haptic sensory input with experiential and explicit knowledge using fuzzy logic feedback. Ultimately, data collected using this methodology may provide the groundwork for the development of an algorithm for robotic mastoidectomy.