Stability of residual low-frequency hearing in children with cochlear implants: Insights from contralateral ear trajectories.

INTRODUCTION

With expanded candidacy, cochlear implantation candidates increasingly present with residual acoustic hearing. The level and stability of residual hearing is particularly relevant when considering electro-acoustic stimulation (EAS). While adult data suggest relative stability, the natural history of residual hearing in children-who often have distinct and potentially progressive etiologies-remains poorly defined.

METHODS

We conducted a retrospective cohort study of pediatric (<18 years) and adult patients who underwent unilateral cochlear implantation. Inclusion required contralateral (non-implanted) low-frequency pure-tone average (LF-PTA; 250-500 Hz) ≤85 dB HL and interaural difference ≤15 dB HL. One-year changes in LF-PTA, mid-frequency PTA (MF-PTA; 750-2000 Hz), and PTA (500-4000 Hz) were compared using Mann-Whitney U tests. The proportion with clinically meaningful decline (≥15 dB HL) was compared using Fisher's exact test. Longitudinal trajectories were assessed descriptively.

RESULTS

Mean one-year LF-PTA, MF-PTA, and PTA changes between children and adults were not statistically different. However, clinically meaningful LF-PTA decline (≥15 dB) occurred more frequently in children (5/24; 20.83%) than adults (2/46; 4.34%) (p = 0.04). Longitudinal trajectories demonstrated substantial inter-individual variability without a consistent pattern of progressive loss. Etiology-specific trends showed relative stability in birth-related hearing loss, whereas ototoxic, genetic, and enlarged vestibular aqueduct etiologies demonstrated greater decline.

CONCLUSIONS

Residual low-frequency hearing in children is generally stable but more variable, with a higher rate of clinically significant decline than in adults one year post-implant. These findings suggest underlying disease progression contributes to hearing changes and should inform counseling and EAS candidacy.