Long term outcomes of early cochlear implantation in Korea

Abstract

Objectives: The objective of this study was to compare the long-term auditory performance and language skill depending on the age of cochlear implantation in the Korean population. We especially tried to separate the effect of maturation/development from that of the age at implantation.

Methods: Eighty-six pre-lingual children with profound hearing loss who underwent a cochlear implantation before the age of six and had been followed for more than 3 yr were included in this study prospectively. Categories of Auditory Performance (CAP) and Korean Picture Vocabulary Test (K-PVT) were serially followed up. In order to separate the age at implantation effect, K-PVT results were readjusted to the child's chronological age in the normal hearing population.

Results: When the CAP and K-PVT scores were directly compared without chronological readjustment, we failed to show a significant difference for improvements according to the age at implantation. Early cochlear implantation was associated with better language development, only when the K-PVT scores were readjusted to percentile scores of their chronological age.

Conclusion: Early cochlear implantation was associated with better language development even within the critical period. This advantage may be recognized only when the effect of the age at implantation is separated from the effect of maturation/development.

Keywords: Categories of auditory performance; Cochlear implantation; Long term outcome; Maturation; Picture vocabulary test.

Fig. 1

Improvement of the Categories of Auditory Performance (CAP) scores in the different groups over time (3 yr). Each data point represents improvement of the CAP score (the mean CAP score difference between each follow-up time and the preoperative time) for each group over time. Group 1: younger than 2 yr, Group 2: 2-3 yr, Group 3: 3-4 yr, Group 4: 4-6 yr. CAP: Categories of Auditory Performance.

Fig. 2

The K-PVT absolute score in the different groups over time (3 yr). Each data point represents the improvement of the K-PVT score (the mean K-PVT score difference between each follow-up time and the preoperative time) for each group over time. Group 1: younger than 2 yr, Group 2: 2-3 yr, Group 3: 3-4 yr, Group 4: 4-6 yr. K-PVT: Korean Picture Vocabulary Test.

Fig. 3

The K-PVT percentile score among groups over time (3 yr). Each data point represents the improvement of the K-PVT percentile score (the mean K-PVT percentile score difference between each followup time and the preoperative time) for each group over time. Group 1: younger than 2 yr, Group 2: 2-3 yr, Group 3: 3-4 yr, Group 4: 4-6 yr. K-PVT: Korean Picture Vocabulary Test.