Comparative Long-Term Outcomes of Lateral Wall and Slim Modiolar Cochlear Implant Electrodes in Children With Normal Cochlear Anatomy

BACKGROUND: Electrode design may influence neural stimulation efficiency, speech outcomes, and long-term stability. While both lateral wall and slim modiolar electrodes are widely used in pediatric cochlear implantation, comparative long-term outcome data in children with normal cochlear anatomy remain limited. METHODS: This retrospective comparative study included children with bilateral prelingual severe-to-profound sensorineural hearing loss who underwent cochlear implantation with either a lateral wall electrode (CI522/622) or a slim modiolar electrode (CI532/632) at a tertiary academic center between 2017 and 2021. All children had normal cochlear anatomy and a minimum follow-up of 4 years. Demographic data, surgical details, intraoperative electrophysiologic measures, postoperative audiologic and speech outcomes, data logging, and radiologic assessments were analyzed. RESULTS: A total of 161 ears were included (83 lateral wall, 78 slim modiolar). Mean age at implantation did not differ between groups. The slim modiolar group demonstrated significantly lower intraoperative NRT thresholds and impedance values, higher 4-year speech discrimination scores (75.5% vs. 68.8%; P=0.001), and greater mean daily device use (11.2 vs. 9.7 h; P=0.02). Electrode migration occurred exclusively in the lateral wall group (8.4%), while none was observed in the slim modiolar group. Suspected scalar translocation was uncommon overall but more frequent with lateral wall electrodes (4.8% vs. 1.2%; P=0.02). CONCLUSION: In children with normal cochlear anatomy, slim modiolar electrodes were associated with superior long-term speech outcomes, lower stimulation requirements, greater device use, and improved intracochlear stability compared with lateral wall electrodes.