Vocabulary acquisition rate after pediatric cochlear implantation and the impact of age at implantation

Objective: studies of early vocabulary development after pediatric cochlear implantation show growth rates that approach normality. Do these growth ra tes continue to rise over time and, therefore, allow a 'catch up' with idea l scores for age, or do they decline after an initial peak. Could age at im plantation be a decisive factor in that process? Design: retrospective stud y (mean follow-up 4 years). Patients: pre-lingually deaf children implanted between 1988 and1999, who serially performed Peabody Picture Vocabulary Te st-Revised (PPVT), (37 patients) and Expressive One-word Picture Vocabulary Test-Revised (EOWPVT), (35 patients). Outcome measures: the mean rates of age equivalent scores were determined for the whole follow-up period and an alyzed further for two post-implant periods (the two halves of follow-up du ration of individual patients). After sub-grouping by age at implantation ( younger or older than 5 years old), the same analysis was executed for each subgroup. Results: the mean EOWPVT rate of the earlier period was higher t han that of the later period (1.33 vs. 0.67, P < 0.01) and the mean PPVT ra te of the earlier period was higher than that of the later period (0.72 vs. 0.5). The latter difference was not statistically significant (P > 0.05). Within subgroups by age at implantation, the PPVT mean rates were stable fo r younger implanted patients (0.56 for both periods) and dropped for the ol der implanted sub-group (0.87-0.43, P > 0.05). The EOWPVT mean rates declin ed significantly for the older patients group (1.72-0.55, P < 0.01) but ins ignificantly for the younger patients (0.99-0.77, P > 0.05). Conclusions: v ocabulary acquisition rates decline in the post-implantation period. This i s more pronounced with older implanted children and the EOWPVT rates. This information on the time course development of vocabulary after implantation would be valuable in counseling and planning habilitation in addition to c andidate selection. (C) 2001 Published by Elsevier Science Ireland Ltd. All rights reserved.