Background and aim
Most cochlear implant (CI) recipients are fitted with a default frequency allocation map that recreates the cochlear tonotopic organization, but does not take individual variability in size and shape of the cochlea into account. Therefore, there is likely to be a mismatch between the tonotopic frequency and the fitted center frequency of the electrode contact at the same tonotopic location (i.e. frequency-to-place mismatch). The surgical planning software OTOPLAN (CAScination AG, Bern/Switzerland) is able to determine the position and center frequency of each individual electrode contact, using post-operative CT images. This allows the audiologist to set a frequency-band distribution for CI fitting that is more closely aligned to the natural tonotopic frequency distribution of the organ of Corti and the spiral ganglion of a normal hearing cochlea (i. e. anatomy-based fitting (ABF)). The aim of this study is to evaluate audiological outcomes in patients with an individualized anatomy-based frequency distribution and to compare outcomes with patients with a conventional frequency distribution.
Methods
In this prospective longitudinal study, eleven newly implanted patients with a bilateral severe-to-profound sensorineural hearing loss (SNHL) are included. Patients are randomized in one of the two study arms: patients randomized in the control group are fitted with a conventional logarithmic frequency distribution, whereas patients in the intervention group are fitted with an anatomy-based frequency distribution. Minimal Outcome Measurements (MOM), consisting of pure-tone audiometry, speech understanding in quiet, speech understanding in noise and a self-perceived auditory benefit questionnaire (HISQUI19), are performed pre-operatively, at 3 months and at 6 months post-activation of the audioprocessor.
Preliminary results
There is no statistically significant difference in pure-tone audiometry, speech perception in quiet, speech perception in noise and self-perceived auditory benefit between patients with a conventional and an anatomy-based frequency distribution of the fitting map at 3 months and 6 months post-activation of the audioprocessor. Furthermore, there is a positive significant correlation between the electrode insertion angle and the speech perception in quiet outcomes for ABF fitted patients at 3 months post-activation.
Conclusion
Our preliminary results demonstrate a similar performance in newly implanted patients with an anatomy-based fitting map in comparison to patients with a conventional fitting map. We recommend to select the most suitable electrode array for complete cochlear coverage to obtain optimal performance with ABF. Further investigation in a larger population is ongoing and necessary to assess the benefits of anatomy-based fitting.

**Background and aim**
Most cochlear implant (CI) recipients are fitted with a default frequency allocation map that recreates the cochlear tonotopic organization, but does not take individual variability in size and shape of the cochlea into account. Therefore, there is likely to be a mismatch between the tonotopic frequency and the fitted center frequency of the electrode contact at the same tonotopic location (i.e. frequency-to-place mismatch). The surgical planning software OTOPLAN (CAScination AG, Bern/Switzerland) is able to determine the position and center frequency of each individual electrode contact, using post-operative CT images. This allows the audiologist to set a frequency-band distribution for CI fitting that is more closely aligned to the natural tonotopic frequency distribution of the organ of Corti and the spiral ganglion of a normal hearing cochlea (i. e. anatomy-based fitting (ABF)). The aim of this study is to evaluate audiological outcomes in patients with an individualized anatomy-based frequency distribution and to compare outcomes with patients with a conventional frequency distribution.
**Methods**
In this prospective longitudinal study, eleven newly implanted patients with a bilateral severe-to-profound sensorineural hearing loss (SNHL) are included. Patients are randomized in one of the two study arms: patients randomized in the control group are fitted with a conventional logarithmic frequency distribution, whereas patients in the intervention group are fitted with an anatomy-based frequency distribution. Minimal Outcome Measurements (MOM), consisting of pure-tone audiometry, speech understanding in quiet, speech understanding in noise and a self-perceived auditory benefit questionnaire (HISQUI19), are performed pre-operatively, at 3 months and at 6 months post-activation of the audioprocessor.
**Preliminary results**
There is no statistically significant difference in pure-tone audiometry, speech perception in quiet, speech perception in noise and self-perceived auditory benefit between patients with a conventional and an anatomy-based frequency distribution of the fitting map at 3 months and 6 months post-activation of the audioprocessor. Furthermore, there is a positive significant correlation between the electrode insertion angle and the speech perception in quiet outcomes for ABF fitted patients at 3 months post-activation.
**Conclusion**
Our preliminary results demonstrate a similar performance in newly implanted patients with an anatomy-based fitting map in comparison to patients with a conventional fitting map. We recommend to select the most suitable electrode array for complete cochlear coverage to obtain optimal performance with ABF. Further investigation in a larger population is ongoing and necessary to assess the benefits of anatomy-based fitting.

Anatomy-based fitting in unexperienced cochlear implant users

It is with great pleasure and enthusiasm, that on behalf of the Cochlear Implant centers of the Radboud UMC in Nijmegen and Erasmus MC Sophia Children’s Hospital in Rotterdam to invite you to attend the 16th European Symposium on Pediatric Cochlear Implantation to Rotterdam, the Netherlands in 2023.

Yours sincerely, on behalf of the CI Centers at Radboud UMC and Erasmus MC,