Individual differences in effectiveness of cochlear implants

Abstract

The efficacy of cochlear implants has been firmly established. However, the effectiveness of cochlear implants varies widely and is influenced by demographic and experiential factors. First, there are enormous individual differences in both adults and children. Some patients show large changes in speech perception whereas others show only modest gains. Second, age of implantation and length of deafness affect outcome measures. Younger children do better than older children and children who have been deaf for shorter periods of time do better than children who have been deaf for longer periods of time. Third, communication mode affects outcome measures. Children from ‘‘oral-only’’ environments do much better than children who use ‘‘total communication.’’ Fourth, there are no preimplant predictors of outcome performance. The underlying abilities and skills ‘‘emerge’’ after implantation. Finally, there are no differences among devices or processing strategies. The pattern of results suggests that processes such as perception, attention, learning, and memory may play an important role in explaining the enormous individual differences. Investigations of the content and flow of information in the central nervous system and interactions between sensory input and stored knowledge may provide new insights into individual differences. [Work supported by NIH-NIDCD Grants DC00012 and DC00111.]