Novel Neuronavigation Interface EVADE for Lateral Skull Base Surgery: The Cadaver Safety Study

Objective: A neuronavigation interface (EVADE) with extended function as compared with current systems was developed to aid during temporal bone surgery. EVADE updates anatomical images to visualize the bone drilling process virtually in real time without need for intraoperative imaging. Furthermore, EVADE continuously calculates the distance from the drill tip to segmented temporal bone structures and produces audiovisual warnings if the drill tip enters a safety zone protecting these structures. Our objectives were (1) to demonstrate that EVADE's warnings prevent damage to structures in cadaver heads when neophytes drill. (2) To show that EVADE's virtual drilling is accurate. Study Design: A cadaver safety study was conducted. Patients/material and Methods: Nine medical students drilled mastoidectomies with different safety zones (1/2/3 mm). Iatrogenic damage to critical structures was assessed. Five temporal bone (trans/retrolabyrinthine) approaches were performed. Correspondence between EVADE's virtual drill cavities and real drill cavities was calculated. Results: Students drilling with a 3-mm safety zone did not damage structures. Students employing a lower safety margin damaged structures. EVADE's virtual drill cavity maximum over- and underestimation errors were 3.0 ± 0.4 and −3.2 ± 0.5 mm, respectively. Conclusions: EVADE protects structures from iatrogenic damage during drilling, under conditions where the “surgeon” has limited anatomical knowledge. EVADE's virtual drilling is accurate.