Anatomy-based CI fitting via preoperative imaging (preopABF)

The use of software for measuring the inner ear anatomy allows for the estimation of the position of the electrode array contacts in the cochlea prior to cochlear implantation, based on the standard preoperative imaging. These estimated contact positions can be used in the cochlear implant (CI) fitting software instead of the standard frequency table (“preopABF”). In initial and follow-up fittings, the preference for preopABF vs. standard fitting was investigated. The electrode positions calculated from preoperatively available CTs and MRIs from clinical routine were recorded using the software OTOPLAN4 (CAScination, Bern, Switzerland; distributed by MED-EL, Innsbruck, Austria). In both initial and follow-up fittings, preopABF and standard fitting were offered in a single-blind manner. If there was a clear subjective preference, only that variant was programmed into the speech processor. In all other cases, both variants were programmed as programs. PreopABF was activated for 47 patients. Of these 47 patients, 6 patients (each bilaterally CI-supplied) declined the experimental comparison of standard frequency allocation and that provided by preopABF (=ipsilateral ear). However, 5 of these 6 patients preferred preopABF on the contralateral ear, regardless of the delay between 1st ear and 2nd ear cochlear implantation. Only one patient rejected preopABF bilaterally and was therefore excluded from further analysis. The remaining 46 patients consented to a comparison between the traditional fitting and the novel preopABF (at least on one ear). In two cases, bilateral preopABF was performed, and in 44 cases, unilateral preopABF was performed. The estimated electrode positions obtained from preoperative CT or MRI using OTOPLAN were successfully used in clinical practice for CI fitting (preopABF) and showed a clear preference over the standard setting in this evaluation. Whether a CI fitting based on postoperative imaging (preopABF) will show a significant patient preference in comparison to standard fitting is still to be investigated.