Tablet Based High Accuracy Navigation on the Lateral Skull Base

Hypotheses: We aimed to develop a surgical navigation system which fulfils the accuracy requirements for surgical procedures on the lateral skull base, is integrable with existing surgical workflows and operating room set ups. Methods: The hardware of the navigation system consists of a light and portable high accuracy tracking system, a wireless Bluetooth communication protocol and a tablet. The software runs on the tablet, guides the user through a fiducial based registration process and allows navigating a surgical pointer in 2D and 3D. Technical accuracy assessment using a custom made phantom was performed. To assess accuracy and usability in a clinical setting we performed three different transcanal endoscopic approaches to the lateral skull base (infracochlear, suprageniculate and transpromontorial) and measured the accuracy on clinically and radiologically identifiable landmarks. Results: We conducted dissection and evaluation of the system on whole head cadaver specimens (n=8). During the experiments, the navigation system was demonstrated to be useful and fully integrable into the surgical workflow. A mean target registration error of 0.15mm was achieved during the technical setup, the measured values during endoscopic dissection was assessed 0.3mm. Conclusion: The developed navigation fulfils the accuracy requirements for ear and latera skull base surgery. The obtained additional information enables the surgeon to safely access the most hidden parts of the petrous apex, using a minimal invasive approach. This system may help to enlarge indications of the transcanal endoscopic approach towards more extended lesions of the lateral skull base.