Assessment of vocabulary development in children after cochlear implantation

Objectives: To assess vocabulary development in children following cochlear implantation and to evaluate the effect of age at implantation on performa nce. Design: Retrospective study (mean follow-up, 3 1/2 years) Setting: Tertiary center. Patients: Children with prelingual deafness provided with a cochlear implan t between 1988 and 1999, who serially performed the Peabody Picture Vocabul ary Test-Revised (60 patients) and the Expressive One-Word Picture Vocabula ry Test-Revised (52 patients). The children were subgrouped into those rece iving implants at younger than 5 years and at 5 years or older. Outcome Measures: Age-equivalent vocabulary test score and gap index (chron ological age minus the age-equivalent score, divided by the chronological a ge at the time of testing) were calculated. For each test, the following we re performed: calculation of rate of change for age-equivalent score; compa rison of earliest and latest gap indices means (the cohort and intergroup a nd intragroup comparison); and multiple regression analysis demonstrating t he effect of age at implantation, sex, communication mode, etiology of deaf ness, and residual hearing on the rate of vocabulary development. Results: Expressive and receptive vocabulary development rates were 0.93 an d 0.71 (age-equivalent scores per year), respectively. Subgrouped by age at implantation, the children's rates (for both vocabularies) were not statis tically different (Peabody Picture Vocabulary Test-Revised, P=.90; Expressi ve One-Word Picture Vocabulary Test-Revised, P=.23). The global latest gap indices were significantly less than the earliest (Peabody Picture Vocabula ry Test-Revised, P=.048; Expressive One-Word Picture Vocabulary Test-Revise d, P<.001), indicating an improvement in age-appropriate vocabulary develop ment over time. The age subgroups demonstrated similar results, except for the younger group's receptive gap index. On multiple regression analysis, t he significant predictive variables were residual hearing (Expressive One-W ord Picture Vocabulary Test-Revised) and male sex and oral communication mo de (Peabody Picture Vocabulary Test-Revised). Conclusions: Children with cochlear implants developed their vocabularies a t rates that were sufficient to prevent an increase in their gap indices as related to ideal scores at testing. A late age at implantation does not si ngularly preclude beneficial development of vocabulary.