Vocabulary Development and Its Influencing Factors Among Cochlear Implanted Children With Cochlear Nerve Aplasia Diagnosed by MRI

Objectives: To evaluate the expressive vocabulary ability of children with cochlear implants diagnosed with cochlear nerve aplasia (CN-A) and analyze potential factors influencing vocabulary development. Study design: Cross-sectional study. Setting: Tertiary referral center. Participants: Thirty-one children diagnosed with CN-A by magnetic resonance imaging (MRI) who received a cochlear implantation (CI) before 3 years old. Interventions: Therapeutic—CI. Main outcome measures: Expressive vocabulary was quantitatively assessed using the Early Vocabulary Inventory for Mandarin Chinese (EVI) after at least 3 years of CI usage. The cochleovestibular nerve diameter to facial nerve diameter ratio (CVN/FN ratio) was evaluated using preimplantation MRI. Preimplantation-aided pure tone average (PTA) was retrospectively reviewed. The relationship between the age of implantation, duration with CI, CVN/FN ratio, preimplantation-aided PTA, prosthetic configuration, and the expressive vocabulary size was analyzed. Results: The mean expressive vocabulary size was 283.60 (SD: 220.12; range: 0 to 628) for children with CN-A. Expressive vocabulary size was significantly correlated with the CVN/FN ratio, preimplantation PTA, and prosthetic configuration ( P s <0.05), whereas age at implantation and duration of CI were not significantly correlated ( P s >0.05). Hierarchical regression models showed that the CVN/FN ratio, preimplantation PTA, and prosthetic configuration independently contributed to predicting expressive vocabulary size ( P s <0.05). Conclusion: Expressive vocabulary abilities are significantly impaired in children with CN-A. Preimplantation CVN size relative to the FN on MRI, residual hearing, and prosthetic configuration are important predictors of vocabulary development in this population.