The effect of age at cochlear implant initial stimulation on expressive language growth in infants and toddlers

Abstract

This study examined the growth of expressive language skills in children who received cochlear implants (CIs) in infancy. Repeated language measures were gathered from 29 children who received CIs between 10 and 40 months of age. Both cross-sectional and growth curve analyses were used to assess the relationship between expressive language outcomes and CI experience. A beneficial effect of earlier implantation on expressive language growth was found. Growth curve analysis showed that growth was more rapid in children implanted as infants than those implanted as toddlers. Age at initial stimulation accounted for 14.6% of the variance of the individual differences in expressive language growth rates.

Figure 1

Number and time of expressive language observations gathered from each participant. On the y-axis, each child is represented by a single tick mark; data from the youngest children implanted are located toward the top of the axis while data from the older children implanted are located toward the bottom of the axis. Time is represented on the x-axis and is measured relative to the number of months following initial stimulation of each child's device. The ◆ represents observations during which data from the Minnesota Child Development Inventory were collected from the child; □ represents observations during which data from the Preschool Language Scale—3 were collected from the child.

Figure 2

Pattern of expressive language growth curves across individual participants. On the y-axis, each child is represented by a single tick mark; to the left of each tick mark is that particular child's chronological age at initial stimulation (in months). The plots are arranged in order relative to each child's age at initial stimulation of the cochlear implant device; data from the children implanted at the youngest age are located toward the top of the plot while data from the children implanted at older ages are located toward the bottom of the plot. Time is represented on the x-axis and is measured relative to the number of months following initial stimulation of each child's device.

Figure 3

This figure displays a three-dimensional plot of expressive language growth based on the parameters derived from the combined language raw scores. Time is represented on the x-axis and is measured relative to the number of months following initial stimulation of each child's device. The combined, expressive language raw scores are on the y-axis and age at initial stimulation is on the z-axis, where children implanted earlier in life (around 12 months of age) are toward the front and children implanted later in life are toward the back.