The potential of the individualized treatment with the new cochlear implant electrode array FLEX34

Using fine-slice imaging (CT, MRI), it is now possible to determine the cochlear length (CDL) preoperatively to cochlear implantation. This allows for individualized cochlear implant implantation adapted to the individual anatomy. Electrode arrays can be inserted virtually using the OTOPLAN4 software (CAScination, Bern, Switzerland; distributed by MED-EL, Innsbruck, Austria). The aim was to investigate how often a particularly long cochlea is present and therefore implantation of the currently longest electrode array, FLEX34, would have been possible. We examined all CI patients in our database with CDL measured via OTOPLAN4 based on the full organ of corti (CDL (full OC)) retrospectively. OTOPLAN4 also allows automatic evaluation in contrast to previous versions. To calculate the potential coverage of a FLEX34, it was assumed according to the manufacturer’s instructions that the apical electrode was at a position of 33.62 mm CDL (full OC). The CDL (full OC) and the electrical cochlear coverage were compared. A total of 196 ears from 99 patients were analyzed with OTOPLAN4. The A value was 9.24±0.80 mm from 7.7 to 15 mm, the average H value was 4.12±0.43 mm from 3.0 to 5.4 mm, the B value was 6.83±0.57 mm from 3.9 to 8.4 mm and the CDL (full OC) at 36.13±2.48 mm from 30.4 to 46.4 mm (each arithmetic mean ± SD from min. to max.). Mean electrical cochlear coverage was 93.04±6.65% from 70.89% to 111.14%. In 28 cases (14.29%) the coverage was ≥100%, in 115 cases (58.67%) 90–100%, in 45 cases (22.96%) 80–90%, and in 7 cases (3.57%) 70–80%. To conclude, at our clinic, a significant proportion of patients have a very large cochlea and would potentially benefit from an even longer electrode such as the FLEX34 resulting in a higher cochlear coverage. Which cochlear coverage should be aimed for individually needs to be examined in more detail in further studies, as there is currently data that recommend around 80% coverage as well as data that suggest the most complete coverage possible to achieve the best possible speech understanding postoperatively.