Frequency reallocation based on cochlear place frequencies in cochlear implants: a pilot study

Purpose: The aim of this study is to evaluate speech perception outcomes after a frequency reallocation performed through the creation of an anatomically based map obtained with Otoplan®, a tablet-based software that allows the cochlear duct length to be calculated starting from CT images. Methods: Ten postlingually deafened patients who underwent cochlear implantation with MED-EL company devices from 2015 to 2019 in the Tertiary referral center University Hospital of Verona have been included in a retrospective study. The postoperative CT scans were evaluated with Otoplan®; the position of the intracochlear electrodes was obtained, an anatomical mapping was carried out and then it was submitted to the patients. All patients underwent pure tonal and speech audiometry before and after the reallocation and the audiological results were processed considering the Speech Recognition Threshold (SRT), the Speech Awareness Threshold (SAT) and the Pure Tone Average (PTA). The differences in the PTA, SAT and SRT values before and after the reallocation were determined. The results were statistically processed using the software Stata with a significance value of α < 0.05. Results: The mean values of SRT (61.25 dB versus 51.25 dB) and SAT (49 dB versus 41 dB) were significantly lower (p: 0.02 and p: 0.04, respectively) after the reallocation. No significant difference was found between PTA values (41.5 dB versus 39.25 dB; p: 0.18). Conclusions: Our preliminary results demonstrate better speech discrimination and rapid adaptation in implanted postlingually deaf patients after anatomic mapping and subsequent frequency reallocation.