Spoken language development in children following cochlear implantation

Abstract

Context: Cochlear implantation is a surgical alternative to traditional amplification (hearing aids) that can facilitate spoken language development in young children with severe to profound sensorineural hearing loss (SNHL).

Objective: To prospectively assess spoken language acquisition following cochlear implantation in young children.

Design, setting, and participants: Prospective, longitudinal, and multidimensional assessment of spoken language development over a 3-year period in children who underwent cochlear implantation before 5 years of age (n = 188) from 6 US centers and hearing children of similar ages (n = 97) from 2 preschools recruited between November 2002 and December 2004. Follow-up completed between November 2005 and May 2008.

Main outcome measures: Performance on measures of spoken language comprehension and expression (Reynell Developmental Language Scales).

Results: Children undergoing cochlear implantation showed greater improvement in spoken language performance (10.4; 95% confidence interval [CI], 9.6-11.2 points per year in comprehension; 8.4; 95% CI, 7.8-9.0 in expression) than would be predicted by their preimplantation baseline scores (5.4; 95% CI, 4.1-6.7, comprehension; 5.8; 95% CI, 4.6-7.0, expression), although mean scores were not restored to age-appropriate levels after 3 years. Younger age at cochlear implantation was associated with significantly steeper rate increases in comprehension (1.1; 95% CI, 0.5-1.7 points per year younger) and expression (1.0; 95% CI, 0.6-1.5 points per year younger). Similarly, each 1-year shorter history of hearing deficit was associated with steeper rate increases in comprehension (0.8; 95% CI, 0.2-1.2 points per year shorter) and expression (0.6; 95% CI, 0.2-1.0 points per year shorter). In multivariable analyses, greater residual hearing prior to cochlear implantation, higher ratings of parent-child interactions, and higher socioeconomic status were associated with greater rates of improvement in comprehension and expression.

Conclusion: The use of cochlear implants in young children was associated with better spoken language learning than would be predicted from their preimplantation scores.

Figure 1

Developmental Trajectories of RDLS Raw Scores of Comprehension and Expression Grouped by Age At Baseline Hearing children in gray (A) <18 months, (B) 18–36 months, and (C) >36 months; mean trajectories of sub-groups by age of enrollment in black. Children undergoing CI: (A) Implant age <18 months in orange, (B) 18–36 months in blue, (C) >36 months in green. Mean trajectories for respective age group in red dash. Mean score after 3 years designated by horizontal line, the width of which spans the age range at time of testing. Mean scores established by baseline (pre-CI) scores of children undergoing CI are shown in each plot in navy blue dash.

Figure 2

Nonparametric Fit of RDLS Raw Scores of Comprehension and Expression Stratified by Age at Baseline and Test Age Children with normal hearing in gray lines (categorized by age at baseline: solid gray line < 18 months; short dashed gray line 18–36 months; and long dashed gray line between >36 months). Children undergoing CI: <18 months at implant age in orange, 18–36 months in cyan dash, and >36 months in green dash. Mean trajectories established by baseline scores of all normal hearing children in black. For comparative assessment, the horizontal, gray line projects the chronological age at which the mean scores of normal hearing children at baseline (30.1 for comprehension and 27.6 for expression) were obtained by sub-group of children undergoing CI at different age. The vertical drop-lines indicate ages at which this score was obtained for each group of children. On the comprehension scale, the ages were 2.3 years for hearing children; 3.4 years for CI <18 months at implant age, 4.7 years for CI 18–36 months at implant age, 5.3 years for CI >36 months at implant age. On the expression scale, the ages were 2.3 years for hearing children; 3.4 years for CI <18 months at implant age, 4.5 years for CI 18–36 months at implant age, and 5.2 years for CI >36 months at implant age.