Influence of DFNB1 status on expressive language in deaf children with cochlear implants

Abstract

Objective: The objective of this study was to compare the language growth of children with connexin-related deafness (DFNB1) who received cochlear implants versus the language growth of implanted children with non-DFNB1 deafness.

Study design: A prospective longitudinal observational study and analysis.

Setting: Two tertiary referral centers.

Patients: There were 37 children with severe-to-profound hearing loss who received cochlear implants before the age of 5 years.

Interventions: A standardized language measure, the section for expressive language of the Reynell Developmental Language Scale was used to assess expressive language skills at 2 times postimplantation (14 and 57 mo postimplantation). Molecular screening for DFNB1 gene variants.

Main outcome measures: Language quotient (LQ) scores (i.e., age-equivalent score obtained on the Reynell Developmental Language Scale divided by the child's chronological age), results of genotyping.

Results: The mean language age at the second time interval (mean ± standard deviation, 51.8 ± 13 mo) was greater than at the first testing session (mean ± standard deviation, 19 ± 8 mo, p < 0.001, Wilcoxon signed rank test). When divided by genotype, DFNB1 children exhibited a higher LQ and less variability in scores than non-DFNB1 children at the second testing interval (Wilcoxon sign rank test, p = 0.0034). A regression analysis (linear-fit by least squares) conducted on 26 children with preimplantation audiometric data showed that DFNB1 status was the independent variable with greater predictive effect on LQ at the second testing interval, followed by age at implantation (R2 = 0.35, p = 0.0479).

Conclusion: Deaf children who received cochlear implants before the age of 5 years and use oral communication show substantial improvement in language abilities. In this study, DFNB1 children who use cochlear implants show greater gains in expressive language than non-DFNB1 children, independent of residual hearing, age at implantation, and duration of implant use.

Figure 1

Language age (calculated from the raw scores of the expressive section of the Reynell Developmental Language Scales [RDLS]) by age at testing in months. The line indicates the linear fit by least-squares regression analysis (Language Age prediction expression = −5.85 + 0.65 × Age Test. R Square = 0.60, p<0.001).

Figure 2

Comparison of language quotient LQ (LQ = language age/chronological age) by DFNB1 status at the two testing intervals. LQ Exp1 and LQ Exp2: LQ calculated with the expressive section of the Reynell Developmental Language Scales at the first (Figure 2A, median duration of implant use is 14 months) and second (Figure 2B, median duration of implant use is 57 months) testing interval, respectively. The large horizontal lines across the boxes represent the population means 95% confidence intervals. The ends of the boxes are the 25th and 75th quartiles. The line across the middle of the boxes identifies the median sample values. The whiskers at the ends of the boxes extend to the outermost data points.

Figure 2

Comparison of language quotient LQ (LQ = language age/chronological age) by DFNB1 status at the two testing intervals. LQ Exp1 and LQ Exp2: LQ calculated with the expressive section of the Reynell Developmental Language Scales at the first (Figure 2A, median duration of implant use is 14 months) and second (Figure 2B, median duration of implant use is 57 months) testing interval, respectively. The large horizontal lines across the boxes represent the population means 95% confidence intervals. The ends of the boxes are the 25th and 75th quartiles. The line across the middle of the boxes identifies the median sample values. The whiskers at the ends of the boxes extend to the outermost data points.