[Correlative research on the development of expressive vocabulary among children with cochlear implants within two...

Objective: To track the growth of expressive vocabulary size in children with cochlear implantation (CI) over the first two years after activation, to compare the differences in expressive vocabulary development among different prosthesis configurations, and to establish milestones for expressive vocabulary development during this period. Methods: A total of 63 children (29 males, 34 females) who received CI before 30 months of age at the Department of Auditory Implantation, Shandong Provincial ENT Hospital, between October 2020 and December 2022 were enrolled. The mean age at CI activation was 16.0 months (SD=5.9). The Infant Checklist of the Early Vocabulary Inventory (EVI) for Putonghua was used to assess expressive vocabulary size at activation and 1, 3, 6, 9, and 12 months post-activation. The Toddler Checklist of the EVI was used at 18 and 24 months post-activation. Based on their hearing intervention mode, children were divided into three groups: unilateral CI (one CI, no contralateral intervention), bimodal stimulation (one CI plus a hearing aid in the contralateral ear), and bilateral CI (CI in both ears). SPSS 23.0 was used for descriptive statistics of expressive vocabulary size at different time points, and R software was used to analyze differences in vocabulary growth rates among the three groups. Results: At 24 months post-activation, expressive vocabulary size ranged from 7 to 677 in the unilateral CI group, 252 to 702 in the bimodal group, and 38 to 686 in the bilateral CI group. All children in three groups produced their first expressive word at 6 months post-activation. The bilateral CI group reached the 10-word milestone at 9 months post-activation, whereas the bimodal and unilateral CI groups reached this milestone at 12 months. All three groups reached the 50-word milestone at 18 months. Both the bimodal and bilateral CI groups reached the 100-word milestone at 18 months, whereas the unilateral CI group reached this milestone at 24 months. There were significant differences in the growth rate of expressive vocabulary among the three groups. Both the bilateral CI group and the bimodal group showed significantly faster growth than the unilateral CI group (P<0.01 for both). No significant difference in vocabulary growth rate was found between the bilateral and bimodal groups (P=0.43). Conclusions: Expressive vocabulary size increases rapidly during the first two years after CI activation in Putonghua-speaking children. Both the bimodal and bilateral CI groups demonstrate faster developmental trajectories than the unilateral CI group. The expressive vocabulary milestones established for Putonghua-speaking children with CI during the first two years post-activation can help clinicians and parents set appropriate expectations. When bilateral cochlear implantation is not an option, the use of a hearing aid in the contralateral ear can promote expressive vocabulary development and help prevent language delays.