The influence of cochlear morphology on deeply insertion in straight and perimodiolar electrode arrays

Objective The aim of this study is to examine the impact of cochlear morphology on deeply inserted electrode arrays and the angular depth of the first basal electrode artifact in perimodiolar and straight electrode arrays.

Methods We retrospectively analyzed 548 patients implanted between 2013 and 2018 with a Cochlear™ Contour Advance®, Cochlear™ slim straight® or Cochlear™ slim modiolar® electrode array and MED EL Flex^Soft, MED EL Flex^EAS, MED EL Flex²⁴ and MED EL Flex²⁸. We measured distance A and B, established by Escudé et al. (2006), angular insertion depth of the first basal and of the apical electrode artifact by rotational tomography.

Results The straight electrode arrays Flex^Soft with a length of 31.5mm and the Flex²⁸ with 28mm reached the highest angular insertion depth measured by the apical electrode artifact. Furthermore, they exhibited a significant increased angular insertion depth of the basal electrode artifact compared to the other included electrode arrays. We could not find a relevant correlation between cochlear morphology measurements and neither the insertion depth of the first basal nor the apical electrode artifact.

Conclusion Straight electrode arrays with the longest length (Flex^Soft and Flex²⁸) reached not only the deepest angular insertion depth for the apical, but also for the basal electrode artifact. Cochlear morphology has no relevant influence on deeply insertion of the basal electrode, but on the apical insertion angle itself. Therefore, electrode array design is decisive of apical and basal angular insertion depth.

Publication History

Article published online:
10 June 2020