Electrode Placement Factors and Their Impact on Spectral Resolution in Pediatric and Adult Cochlear Implant Users

Objective To examine how electrode placement factors—such as mean modiolar distance, scalar location, and angular insertion depth—correlate with postoperative spectral resolution in experienced pediatric and adult CI users. Study Design Retrospective case review. Setting Cochlear implant (CI) program at a tertiary medical center. Patients 47 pediatric CIs (across 47 pediatric patients) and 84 adult CIs (across 74 adult patients). Main Outcome Measure(s) Correlations were used to identify the strengths of the associations between electrode placement and CI-alone spectral resolution measured using a spectral modulation detection task with two modulation rates (0.5 and 1.0 cyc/oct). Linear mixed-effects models with stepwise removal were then used to identify the best predictors of spectral resolution thresholds. Results For adult CI users, electrode placement was not significantly correlated with spectral resolution. For pediatric CI users, larger mean modiolar distance was significantly correlated with better spectral modulation detection at 0.5 cyc/oct. Conclusions Electrode placement differentially affected spectral resolution for pediatric and adult CI users. Mean modiolar distance was most associated with spectral resolution, but only for children with CIs, for whom research has yielded mixed results regarding the relationship between spectral resolution and speech recognition.