The effect of cochlear implantation in development of intelligence quotient of 6-9 deaf children in comparison with normal hearing children (Iran, 2009-2011)

Multidisciplinary Cognitive Function Assessment of Good versus Poor Performance in Children with Cochlear Implants: An Observational Cross-Sectional Study

Introduction  Despite the developing technology of cochlear implants (CIs), implanted prelingual hearing-impaired children exhibit variable speech processing outcomes. When these children match in personal and implant-related criteria, the CI outcome variability could be related to higher-order cognitive impairment. Objectives  To evaluate different domains of cognitive function in good versus poor CI performers using a multidisciplinary approach and to find the relationship between these functions and different levels of speech processing. Methods  This observational, cross-sectional study used the word recognition score (WRS) test to categorize 40 children with CIs into 20 good (WRS/65%) and 20 poor performers (WRS < 65%). All participants were examined for speech processing at different levels (auditory processing and spoken language) and cognitive functioning using (1) verbal tests (verbal component of Stanford-Binet intelligence [SBIS], auditory memory, auditory vigilance, and P300); and (2) performance tasks (performance components of SBIS, and trail making test). Results  The outcomes of speech processing at different functional levels and both domains of cognitive function were analyzed and correlated. Speech processing was impaired significantly in poor CI performers. This group also showed a significant cognitive function deficit, in which the verbal abilities were more affected (in 93.5%) than in the good performers (in 69.5%). Moreover, cognitive function revealed a significant correlation and predictive effect on the CI speech outcomes. Conclusion  Cognitive function impairment represented an important factor that underlies the variable speech proficiency in cochlear-implanted children. A multidisciplinary evaluation of cognitive function would provide a comprehensive overview to improve training strategies.

Longitudinal Development of Verbal and Nonverbal Intelligence After Cochlear Implantation According to Wechsler Tests in German-speaking Children: A Preliminary Study

OBJECTIVES

Intelligence as a construct of cognitive abilities is the basis of knowledge and skill acquisition and the main predictor of academic achievement. As a broad construct, it is usually divided into subdomains, such as nonverbal and verbal intelligence. Verbal intelligence is one domain of intelligence but is not synonymous with specific linguistic abilities like grammar proficiency. We aim to address the general expectation that early cochlear implantation enables children who are hard of hearing to develop comprehensively, including with respect to verbal intelligence. The primary purpose of this study is to trace the longitudinal development of verbal and nonverbal intelligence in children with cochlear implants (CIs).

DESIGN

Sixteen children with congenital hearing loss who received unilateral or bilateral implants and completed at least two intelligence assessments around the age of school entrance were included in the study. The first assessment was performed around 3 years after CI fitting (chronological age range: 3.93 to 7.03 years). The second assessment was performed approximately 2 years after the first assessment. To analyze verbal and nonverbal IQ in conjunction and across children at different ages, we used corresponding standardized and normalized tests from the same test family (Wechsler Preschool and Primary Scale of Intelligence and/or Wechsler Intelligence Scale for Children).

RESULTS

Regarding longitudinal development, both verbal and nonverbal IQ increased, but verbal IQ increased more substantially over time. At the time of the second measurement, verbal and nonverbal IQ were on a comparable level. Nevertheless, we also observed strong inter-individual differences. The duration between both assessments was significantly associated with verbal IQ at the second measurement time point and thus with verbal IQ gain over time. Education mode (regular vs. special kindergarten/school) was significantly correlated with nonverbal IQ at the second assessment time point.

CONCLUSIONS

The results, despite the small sample size, clearly suggest that children with CIs can achieve intellectual abilities comparable to those of their normal-hearing peers by around the third year after initial CI fitting, and they continue to improve over the following 2 years. We recommend further research focusing on verbal IQ assessed around the age of school entrance to be used as a predictor for further development and for the establishment of an individual educational program.

Links of Prosodic Stress Perception and Musical Activities to Language Skills of Children With Cochlear Implants and Normal Hearing

OBJECTIVES

A major issue in the rehabilitation of children with cochlear implants (CIs) is unexplained variance in their language skills, where many of them lag behind children with normal hearing (NH). Here, we assess links between generative language skills and the perception of prosodic stress, and with musical and parental activities in children with CIs and NH. Understanding these links is expected to guide future research and toward supporting language development in children with a CI.

DESIGN

Twenty-one unilaterally and early-implanted children and 31 children with NH, aged 5 to 13, were classified as musically active or nonactive by a questionnaire recording regularity of musical activities, in particular singing, and reading and other activities shared with parents. Perception of word and sentence stress, performance in word finding, verbal intelligence (Wechsler Intelligence Scale for Children (WISC) vocabulary), and phonological awareness (production of rhymes) were measured in all children. Comparisons between children with a CI and NH were made against a subset of 21 of the children with NH who were matched to children with CIs by age, gender, socioeconomic background, and musical activity. Regression analyses, run separately for children with CIs and NH, assessed how much variance in each language task was shared with each of prosodic perception, the child's own music activity, and activities with parents, including singing and reading. All statistical analyses were conducted both with and without control for age and maternal education.

RESULTS

Musically active children with CIs performed similarly to NH controls in all language tasks, while those who were not musically active performed more poorly. Only musically nonactive children with CIs made more phonological and semantic errors in word finding than NH controls, and word finding correlated with other language skills. Regression analysis results for word finding and VIQ were similar for children with CIs and NH. These language skills shared considerable variance with the perception of prosodic stress and musical activities. When age and maternal education were controlled for, strong links remained between perception of prosodic stress and VIQ (shared variance: CI, 32%/NH, 16%) and between musical activities and word finding (shared variance: CI, 53%/NH, 20%). Links were always stronger for children with CIs, for whom better phonological awareness was also linked to improved stress perception and more musical activity, and parental activities altogether shared significantly variance with word finding and VIQ.

CONCLUSIONS

For children with CIs and NH, better perception of prosodic stress and musical activities with singing are associated with improved generative language skills. In addition, for children with CIs, parental singing has a stronger positive association to word finding and VIQ than parental reading. These results cannot address causality, but they suggest that good perception of prosodic stress, musical activities involving singing, and parental singing and reading may all be beneficial for word finding and other generative language skills in implanted children.

Cross-modal plasticity and central deficiencies: the case of deafness and the use of cochlear implants

The primary objective of this chapter is to describe the consequences of central deficiencies on the neurodevelopment of children. We approach this topic from the standpoint of congenital deafness. Thus we first present the current state of knowledge on cortical reorganization following congenital deafness. The allocation of auditory cortices to other sensory systems can enhance sensory processing and therefore the cognitive functions related to them. Second, we explore the linguistic development of deaf children. Given that the English written system is speech-based, its acquisition is complex and atypical for deaf children, usually leading to poorer achievements. Next, we explore the impact of a neural prosthesis named the cochlear implant on the neurocognitive and linguistic development of deaf children. In some cases, it allows the individuals to, at least partially, regain access to the lost sense. We also comment on the specific needs of the deaf population when it comes to neuropsychological assessment. Finally, we touch on the specific context of deaf children born of deaf parents, and therefore naturally exposed to sign language as the only means of communication.

Estimation of Mean Intelligence Quotient with Wechsler Scale in Iran: Systematic Review and Meta-Analysis

The low intelligence quotient (IQ) level is one of the most common and important medical, social, and familial problems in all countries. The current study aimed to estimate mean IQ with the Wechsler scale in Iran by performing a systematic review and meta-analysis. In the current meta-analysis, all articles related to IQ conducted in Iran using the Wechsler scale were deeply searched by reviewing citation databases including Science Direct, PubMed, Scopus, Web of Science, Springer, SID, Magiran, Iranmedex, Medlib, and Google Scholar motor search and using valid keywords without time limits. Due to heterogeneity between studies, a random effects model was used to combine the results of studies. To investigate the heterogeneity of the studies, the I2 index was used. All statistical analyses were performed using STATA software version 11.1. The number of participants in the 51 studies was 5352. The mean total IQ score in Iran was estimated 97.12 (95% confidence interval [CI]: 88.71-105.52), the practical intelligence was 92.84 (95% CI: 79.14-106.55), and the verbal intelligence was 94.50 (95% CI: 83.90-105.10). The total IQ score in the northern, southern, central, eastern, and western regions of Iran was 97.08, 108.90, 92.31, 101.76, and 96.45, respectively. The mean IQ score in Iran in subjects under 20 years of age is 97.73 and in subjects over 20 years of age is 105.61. There is also no significant relationship between the mean total IQ in Iran and two parameters of the year of research and number of research samples. For prevention of decrease IQ and given that proper nutrition and breastfeeding directly contribute to increase IQ, nutrition should be provided free of charge in poorer areas during pregnancy until baby born. Moreover, the media should provide adequate education for breastfeeding and nutrition, because IQ affects people's academic, occupational, personal, and social performance, and also prevents elite immigration with suitable planning and provides conditions for elites to return to the country.

Benefits of simultaneous bilateral cochlear implantation on verbal reasoning skills in prelingually deaf children

BACKGROUND

Impaired auditory speech perception abilities in deaf children with hearing aids compromised their verbal intelligence enormously. The availability of unilateral cochlear implantation (CI) auditory speech perception and spoken vocabulary enabled them to reach near ageappropriate levels. This holds especially for children in spoken language environments. However, speech perception in complex listening situations and the acquisition of complex verbal skills remains difficult. Bilateral CI was expected to enhance the acquisition of verbal intelligence by improved understanding of speech in noise.

METHODS

This study examined the effect of bilateral CI on verbal intelligence of 49 deaf children (3;5-8;0 years). Relations between speech perception in noise, auditory short-term memory and verbal intelligence were analysed with multiple linear regressions. In addition, the interaction of educational setting, mainstream or special, on these relations was analysed.

RESULTS

Children with bilateral CI obtained higher scores on verbal intelligence. Significant associations were present between speech perception in noise, auditory short-term memory and verbal intelligence.

CONCLUSION

Children with simultaneous bilateral CIs showed better speech perception in noise than children with unilateral CIs, which mediated by the auditory short-term memory capacity, enhanced the ability to acquire more complex verbal skills for BICI children in mainstream education.

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.

Comparison of Auditory Perception in Cochlear Implanted Children with and without Additional Disabilities

BACKGROUND

The number of children with cochlear implants who have other difficulties such as attention deficiency and cerebral palsy has increased dramatically. Despite the need for information on the results of cochlear implantation in this group, the available literature is extremely limited. We, therefore, sought to compare the levels of auditory perception in children with cochlear implants with and without additional disabilities.

METHODS

A spondee test comprising 20 two-syllable words was performed. The data analysis was done using SPSS, version 19.

RESULTS

Thirty-one children who had received cochlear implants 2 years previously and were at an average age of 7.5 years were compared via the spondee test. From the 31 children, 15 had one or more additional disabilities. The data analysis indicated that the mean score of auditory perception in this group was approximately 30 scores below that of the children with cochlear implants who had no additional disabilities.

CONCLUSION

Although there was an improvement in the auditory perception of all the children with cochlear implants, there was a noticeable difference in the level of auditory perception between those with and without additional disabilities. Deafness and additional disabilities depended the children on lip reading alongside the auditory ways of communication. In addition, the level of auditory perception in the children with cochlear implants who had more than one additional disability was significantly less than that of the other children with cochlear implants who had one additional disability.