Salar translocation with perimodiolar electrode arrays and their impact on speech perception

Introduction In cochlear implant surgery, atraumatic insertion of the electrode array is essential regarding residual hearing and speech perception (SP). The scala tympani (ST) position is considered the optimum. According to literature, lateral arrays (LW) show an ST position more often than perimodiolar arrays (PM). The aim of this study was to compare two PME with different diameters and insertion techniques (CI512 and CI532, cochlear) and investigate scalar position and SP.

Methods 240 adults with post lingual profound hearing loss and a normal anatomy where implanted between 2015 and 08/2018 with CI512 or CI532. The array position was controlled postoperatively by CT-scan. The position was assessed independently by an experienced surgeon and radiologist. SP was measured in a subgroup with CI experience over 1 year (n = 195) using Freiburg monosyllable test.

Results 83.3 % of all electrodes showed an ST position, 1.3 % a scala vestibuli (SV) position. A scalar dislocation (SD) was found at 15.4 %. The CI532 showed a more frequent ST position (95.9 %) than the CI512 (70.1 %). There was no primary SV position in CI532. SD occurred in 4.1 % of CI532 cases and in 27.3 % of CI512 cases. Postoperative SP was 67.8 % in patients with ST location and 62.2 % when SD occurred. This difference was not significant, not even was SP between CI512 and CI532.

Conclusion A structure preserving implantation in ST position can be achieved with the investigated PM electrode arrays. According to literature the CI532 shows comparable results with LW electrode arrays and a low incidence of SD. The SD with CI512 is comparable with data of the literature. Our data do not show a significant influence of SD on SP, perhaps more precise audiological measurements have to be performed.

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Publication History

Article published online:
10 June 2020