Language-acquisition After Early Bilateral Cochlear Implantation in the First Six Years of Life

Objective: To investigate the development of language acquisition and speech perception in cochlear-implant (CI) recipients in relation to standardized norms using a language-acquisition test and speech-perception tests. Study design: Retrospective analysis. Setting: Tertiary hospital. Patients: One hundred forty-two participants who received bilateral CIs before the age of 24 months (age at implantation M = 9.61, SD: 3.95), with German as their first language, and without additional disabilities. Age at testing ranged from 2 to 6 years. Intervention: Bilateral cochlear implantation within the first 2 years of life. Main outcome measure: German language-acquisition test for children aged 2.0 to 2.11 and 3.0 to 5.11; Freiburger Monosyllabic word test, Hochmair, Schulz, and Desoyer Sentence Test in quiet and noise were used. Results were statistically evaluated using the t test for pairwise comparisons and ANOVA for comparisons of multiple dependent groups. P- values were Bonferroni-corrected. Results: The mean of all patients’ data indicates that language production, receptive language, and auditory memory were within the range of age-appropriate, normal-hearing listeners, except for sentence production, which was reduced in the 2-year-old group. Over time, patients showed significant increases in language production, as indicated in the comparison of all final test results from 2 to 6 years. In addition, implantation before 12 months of age resulted in significantly better results in speech and language development than implantation between 12 and 24 months. A significant correlation was found between understanding sentences in noise and speech production/speech comprehension, but not understanding in quiet. Conclusions: Bilateral cochlear implantation is recommended before the age of 12 months, as there is less variability in the data on their hearing and in speech-acquisition performance than with a later implantation age of up to 24 months. In addition, if language acquisition is not age-appropriate, there is a greater likelihood that further diagnostic and therapeutic intervention will be needed before children enter school. Comprehensive audiological tests and speech development tests should therefore be carried out continuously during the first 6 years of life.