Predicting most comfortable listening levels of ESRT from ECAP thresholds in paediatric cochlear implant users

Studies have reported a varied correlation strength between the electrically evoked compound action potential (ECAP) and electrically evoked stapedial reflex thresholds (ESRT) in cochlear implant recipients. However, there is a lack of information on the relationship between the two measures in paediatric cochlear implant users. This study was aimed to compare the ESRT and ECAP measures and determine where ECAP thresholds fall within the dynamic range of ESRT-based Maps in paediatric cochlear implant users. The study involved 40 children aged between 3 and 6 years and were implanted with MedEL cochlear implant device unilaterally. ESRT and ECAP thresholds were measured for all twelve electrodes during the same mapping session, three months after cochlear implant activation. The results revealed significant differences between ECAP and ESRT thresholds across all electrodes. A significant moderate correlation between ESRT and ECAP thresholds was observed on all electrodes. The ECAP thresholds could predict the ESRT based Most comfortable levels (MCLs) significantly. Notably, ECAP thresholds fell by 17-34 % from the upper stimulation levels of ESRT-based maps across the electrodes. This study's findings have significant implications for programming cochlear implants in paediatric patients. For children who are unable to cooperate during ESRT measurements, or in cases where ESRT cannot be elicited, ECAP measurements offer a viable alternative. ECAP-based estimates can be used to set MCL levels that closely approximate those derived from ESRT, ensuring appropriate stimulation levels for these young children using cochlear implants.