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.