Comparative Performance of Lateral Wall and Perimodiolar Cochlear Implant Arrays

Objective:The physical shape of cochlear implant (CI) arrays may impact hearing outcomes. The goal of this study was to compare post-operative speech and melody perception between patients with lateral wall (LW) and perimodiolar (PM) electrode arrays across a range of lengths and manufacturers.Study Design:Retrospective chart review.Setting:Tertiary Care Hospital.Patients:119 adult patients with post-lingual hearing loss who underwent cochlear implantation.Main Outcome Measures:A total of seven different electrodes were evaluated including 5 different LW electrodes (CI422 [Cochlear American], 1J [Advanced Bionics], Medium [Med El], Standard [Med El], Flex28 [Med El]) and 2 PM electrodes (Contour [Cochlear American], MidScala [Advanced Bionics]). Speech perception outcomes (n=119 patients) were measured by Consonant-Nucleus-Consonant (CNC) scores collected 3, 6, 12 and 24 months after implantation. Melody perception outcomes (n=35 CI patients and n=6 normal hearing patients) were measured by Melodic Contour Identification (MCI).Results:CNC scores increased over time after implantation across all array designs. PM designs exhibited higher CNC scores compared to LW electrodes, particularly 6-months after implantation. Pre-operative pure tone averages did not correlate with post-operative CNC scores. PM arrays outperformed LW electrodes in terms of MCI scores.Conclusions:The physical shape of cochlear implant electrode arrays may impact hearing performance. Compared to LW designs, PM arrays appear to offer superior speech perception during the first 6 months after implantation, with performance equalizing between groups by 24 months. Compared to LW designs, PM arrays also appear to afford superior melody perception.