Chronological changes of stimulation levels in prelingually deafened children with cochlear implant

This study investigated changes in long-term cochlear implant MAPs (values of the program to stimulate electrodes) in children, and examined whether there were significant differences between children and adults. Ten prelingually deafened children (aged from 2.7 to 7.8 years) who received the Nucleus 22 cochlear implant at Kyoto University between 1996 and 1998 participated in this study. Behavioral thresholds (T levels) and maximal comfortable levels (C levels) were evaluated at 3 months post-implant, and then every 6 months up to 4 years. Ten adult cochlear implant users were also evaluated as a control group. All subjects had used their implant for at least 4 years after device connection. All prelingually deafened children demonstrated slower but continuous improvements in speech perception and production abilities during the test period. T levels became stable at 30 months post-implant in children and at 24 months post-implant in adults. C levels became stable at 6 months post-implant in children and within 3 months post-implant in adults. In conclusion, T levels of prelingually deafened children became stabilized 30 months post-implant, while C levels stabilized 6 months post-implant. MAPs of prelingually deafened children were stabilized 30 months post-implant, which was longer than that in adult cochlear implant users.