Intelligence development of pre-lingual deaf children with unilateral cochlear implantation

Objective: The present study aims to test whether deaf children with unilateral cochlear implantation (CI) have higher intelligence quotients (IQ). We also try to find out the predictive factors of intelligence development in deaf children with CI.

Methods: Totally, 186 children were enrolled into this study. They were divided into 3 groups: CI group (N = 66), hearing loss group (N = 54) and normal hearing group (N = 66). All children took the Hiskey-Nebraska Test of Learning Aptitude to assess the IQ. After that, we used Deafness gene chip, Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) methods to evaluate the genotype, auditory and speech performance, respectively.

Results: At baseline, the average IQ of hearing loss group (HL), CI group, normal hearing (NH) group were 98.3 ± 9.23, 100.03 ± 12.13 and 109.89 ± 10.56, while NH group scored higher significantly than HL and CI groups (p < 0.05). After 12 months, the average IQ of HL group, CI group, NH group were99.54 ± 9.38,111.85 ± 15.38, and 112.08 ± 8.51, respectively. No significant difference between the IQ of the CI and NH groups was found (p > 0.05). The growth of SIR was positive correlated with the growth of IQ (r = 0.247, p = 0.046), while no significant correlation were found between IQ growth and other possible factors, i.e. gender, age of CI, use of hearing aid, genotype, implant device type, inner ear malformation and CAP growth (p > 0.05).

Conclusions: Our study suggests that CI potentially improves the intelligence development in deaf children. Speech performance growth is significantly correlated with IQ growth of CI children. Deaf children accepted CI before 6 years can achieve a satisfying and undifferentiated short-term (12 months) development of intelligence.