Comparison of cognitive function in deaf children between before and after cochlear implant.

OBJECTIVES

This study was conducted to examine improvements of cognitive abilities after cochlear implantation in deaf children. We also examined the psychosocial factors that predict good outcomes of cochlear implantation.

DESIGN

A neuropsychological test battery was administered to 17 deaf children (mean age, 7 yr 2 mo) before receiving the cochlear implant, and they were reassessed with the same test at 6-mo follow-up. Their parents completed questionnaires concerning their medical and educational history, parenting style, and parental emotional problems.

RESULTS

Deaf children showed marked improvement in speedy and delicate motor coordination and visual organization abilities. Their cognitive functions of comprehension, concentration, and sequential processing, as measured by nonverbal tests, were found to have improved from the levels of borderline to mild mental retardation to that of near-normal range. However, their performances on Information, Comprehension and Similarity, and Mathematics subtests requiring verbal abilities did not show significant changes. Deaf children's working memory improved significantly after cochlear implantation. However, they showed more omission errors in the visual attention test at follow-up than before cochlear implantation. Such inattentiveness for visual stimuli in children post-implantation could be attributed to distractibility of these children toward external noise. Mothers' depression was negatively correlated with scores of acquired knowledge of deaf children.

CONCLUSION

At the 6-mo follow-up after cochlear implant, deaf children showed marked improvement in nonverbal cognitive functions and working memory. Conversely, their verbal abilities did not significantly change. Maternal factors were found to be important for predicting the prognosis of cochlear implantation. The absence of a control group precludes the possibility of drawing any firm conclusions because the effect of the implant cannot be teased apart from the effects of maturation and training. Future studies should address this question with the use of appropriate control groups.