Responsiveness of cochlear nerve in paediatric cochlear implant users with good and poor speech perception outcomes

The temporal responsiveness of auditory nerve fibres was assessed using the electrically evoked compound action potential refractory recovery function (eCAP-RRF). The eCAP-RRF was measured across basal, middle, and apical electrodes in paediatric cochlear implant (CI) users with varying speech perception outcomes.

The eCAP-RRF measurement included absolute refractory period (ARP), relative refractory period (RRP), and maximum eCAP amplitude. The eCAP-RRF measured in one electrode each in basal, middle, and apical regions. Speech perception abilities were estimated using closed-set picture identification test.

Thirty-four paediatric CI recipients, sub-grouped into good and poor speech perception outcomes.

Two-way mixed-effects ANOVA revealed a significant difference in ARP between participant groups with no significant differences in other measures. Children with poor speech perception exhibited significantly longer ARP across the electrodes compared to those with good speech perception outcomes. Electrode location significantly impacted all eCAP-RRF measures. Pearson's correlation analysis indicated that none of the eCAP-RRF measures were significantly correlated with speech perception abilities or age at implantation.

Measurement of ARP could be a useful tool to understand the variable outcomes among CI users. Further research is necessary to explore the practical importance of prolonged ARP in adjusting stimulation parameters to optimise outcomes.