Use of bone anchoring device in electromagnetic computer-assisted navigation in lateral skull base surgery

The use of the bone anchoring device associated with a fiducial marker, both fixed close to the operating field, improves the reproducibility and effectiveness of the computer-assisted navigation in lateral skull base surgery.Computer-assisted navigation in lateral skull base surgery using the electromagnetic system Digipointeur(®) needs an external fiducial marker (titanium screw) close to the operating field to increase position accuracy (PA) to about 1 mm. Displacement of the emitter placed in the mouth (Buccostat(®)) induces a drift of the system, leading to at least 20% of unsuccessful procedures. The aim of this study was to evaluate the PA, stability, and reproducibility of computer-assisted navigation in lateral skull base surgery using a bone anchoring device to provide a fixed registration system near the operating field.Forty patients undergoing a lateral skull base procedure with the Digipointeur(®) system performed with both the titanium screw and bone anchoring device were included in this prospective study. They were divided in two groups. In the first one (n = 9), the PA was measured before and after screw registration for five intratemporal landmarks, during a translabyrinthine approach. In the second group (n = 31), all lateral skull base procedures were included and the PA was evaluated visually by the surgeon on different landmarks of the approaches as well as the stability of the system.In the first group, the PA was 7.08 ± 0.59 mm and 0.77 ± 0.17 mm (mean ± SEM, p0.0001) before and after screw registration, respectively. In the second group, the PA was considered as accurate by the surgeon in all cases and no drift of the system was observed. Computer-assisted surgery was never abandoned due to increased stability of the bone-anchored emitter.