Automated insertion of preformed cochlear implant electrodes: evaluation of curling behaviour and insertion forces on an artificial cochlear model.

Purpose: As a substantial part of our concept of a minimally invasive cochlear implant (CI) surgery, we developed an automated insertion tool. Studies on an artificial scala tympani model were performed in order to evaluate force application when using the insertion tool.
Methods: Contour electrodes were automatically inserted into a transparent cochlea model in Advance Off-Stylet technique. Occurring forces were measured by the use of a load cell and correlated with observed intracochlear movement of the electrode carriers.
Results: Mean insertion forces were measured up to 20 mN comparable to previous studies on temporal bones. The most influencing factor is the implant's 2D curling behaviour in comparison to the 3D helical shape of the cochlea.
Conclusion: The study confirms the functionality and reliability of the automated insertion tool for insertion of preformed CI. Improved insertion strategies considering patient-specific anatomy become possible.