Radiological evaluation of a new straight electrode array compared to its precursors

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OTOLOGY

Radiological evaluation of a new straight electrode array compared to its precursors Manuel Christoph Ketterer1   · A. Aschendorff1 · S. Arndt1 · I. Speck1 · A. K. Rauch1 · R. Beck1 · F. Hassepass1 Received: 14 September 2020 / Accepted: 10 October 2020 © The Author(s) 2020

Abstract Objective  The aim of this study is to examine electrode array coverage, scalar position and dislocation rate in straight electrode arrays with special focus on a new electrode array with 26 mm in lengths. Study design  Retrospective study. Setting  Tertiary academic center. Patients  201 ears implanted between 2013 and 2019. Main outcome measures  We conducted a comparative analysis of patients implanted with lateral wall electrode arrays of different lengths (F24 = MED-EL ­Flex24, F26 = MED-EL ­Flex26, F28 = MED-EL ­Flex28 and F31.5 = MED-EL ­FlexSoft). Cone beam computed tomography was used to determine electrode array position (scala tympani (ST) versus scala vestibuli (SV), intracochlear dislocation, position of dislocation and insertion angle). Results  Study groups show no significant differences regarding cochlear size which excludes influences by cochlear morphology. As expected, the F24 showed significant shorter insertion angles compared to the longer electrode arrays. The F26 electrode array showed no signs of dislocation or SV insertion. The electrode array with the highest rate of ST dislocations was the F31.5 (26.3%). The electrode array with the highest rates of SV insertions was the F28 (5.75%). Most of the included electrode arrays dislocate between 320° and 360° (mean: 346.4°; range from 166° to 502°). Conclusion  The shorter F24 and the new straight electrode array F26 show less or no signs of scalar dislocation, neither for round window nor for cochleostomy insertion than the longer F28 and the F31.5 array. As expected, the cochlear coverage is increasing with length of the electrode array itself but with growing risk for scalar dislocation and with the highest rates of dislocation for the longest electrode array F31.5. Position of intracochlear dislocation is in the apical cochlear part in the included lateral wall electrode arrays. Keywords  Cochlear implant · Electrode array · Dislocation · Scalar position · Cone beam computed tomography

Introduction All manufacturers diversify their electrode array portfolio more and more regarding shape, size, diameter and flexibility to enable the personalized choice of the implant. The relationship between cochlear morphology, electrode array position and postoperative speech discrimination is of increasing interest. Aschendorff et al. [2] first * Manuel Christoph Ketterer manuel.christoph.ketterer@uniklinik‑freiburg.de 1



Department of Otorhinolaryngology‑Head and Neck Surgery, Faculty of Medicine, Medical Center‑University of Freiburg, University of Freiburg, Killianstrasse 5, 79106 Freiburg, Germany

examined scalar position via rotational tomography for patients inserted with a C ­ ochlear® Contour (n = 21) versus ® a ­Cochlear Contour A ­ dvance® (n = 22) e