Surgical Planning of Temporal Bone Skull Base Defects Using 3D Patient-Specific Models

The middle cranial fossa (MCF) approach provides exceptional exposure to the internal auditory canal, tegmen tympani, tegmen mastoideum, petrous apex, and labyrinthine and tympanic segment of the facial nerve including the geniculate ganglion. The MCF approach is used for the resection of skull base tumors, repair of tegmen dehiscences with associated cerebrospinal fluid (CSF) leak, and superior semicircular canal dehiscences. The MCF approach is a valuable yet technically challenging technique: the MCF floor can be a featureless, flat, and smooth surface lacking clear and distinct landmarks. While the arcuate eminence has classically guided skull base surgeons to the location of the superior semicircular canal, it has been often described as being anterior, posterior, or altogether absent. Thus, the lack of reliable and distinct anatomic landmarks that are inconsistent from patient to patient can present significant difficulties.

Augmented reality (AR) offers a new approach to overcome these anatomical or lack of anatomical landmarks at the MCF. To address these limitations, we consider the effectiveness of two different modalities of AR techniques in improving the surgeon’s identification of key temporal bone anatomy and pathology.

AR techniques consisting of 3D images presented on a computer monitor and hybrid-reality holographic superimposed images projected into real space are compared with the traditional controls, standard CT and MRI. In part 1 of the study, for each of the three modalities, participants were asked to identify key structures in the inner ear and were timed during the task. Afterward, the temporal, physical, and mental demand of the tasks were assessed through the NASA Task Load (TL) Index. In part 2 of the study, for each of the three modalities, participants were asked to identify the pathology and the intimately associated inner ear structures and were timed during the task. Similarly, the NASA TL Index was used to assess temporal, physical, and mental demand. The mean time and NASA TL Index scores were computed for each modality and compared.

By allowing the surgeon to visualize and interact with the area of interest in new dimensions, these innovative forms of visualization offer key insights into the anatomical landscape that are unclear or absent from traditional images. Ultimately, these visualizations have the potential to improve surgical outcomes in skull base disorders that employ the MCF approach.