Electrode contact estimation based on preoperative versus postoperative imaging as a basis for anatomy-based fitting

Abstract Anatomy-based fitting (ABF) has the potential to lead to better outcomes than conventional clinically-based fitting (CBF). It has already been shown that anatomy-based fitting based on postoperative imaging (postopABF) can improve speech understanding. Moreover, it was demonstrated that patients preferred anatomy-based fitting maps based on preoperative imaging (preop ABF) over CBF. The goal of this study was to examine if a difference between preopABF and postopABF could be observed. Via the software OTOPLAN4 (CAScination, MED-EL) the electrode position was calculated based on preoperatively, as part of the clinical routine, obtained imaging (CT or MRI). If necessary, after the cochlear implantation surgery the selected electrode array was adapted if a different array was chosen intraoperatively. This data was exported into the fitting software MAESTRO to enable a preopABF. The same process was done based on postoperative imaging (CT) so that 1) the frequency bands were compared between preopABF and postopABF data and 2) the difference was displayed in semitones. 27 Patients could be included who got a postoperative CT scan. In addition, subjective tinnitus and dizziness or imbalance issues did not significantly change from the pre-operative appointment over the first fitting to the control fitting one month later. In this study, we could show that there is no significant difference between apical to medial and a significant difference for medial to basal electrode contacts between the preopABF and postopABF regarding the frequency bands. Thus, preopABF is an easy, clinically practicable way to implement ABF, which is promising to lead to better outcomes without extra costs and the radiation burden that comes with postopABF. If patients subjectively prefer either preopABF or postopABF is still to be examined.