Bilateral CI Shows Positive Effect on Language

Results of a study on the effect of cochlear implantation (CI) on language development found that bilateral implantation was more advantageous than unilateral implantation in pediatric patients, according to findings reported in the Archives of Pediatrics & Adolescent Medicine [2012;166(1):28-34]. Current data show that >50% of the profoundly deaf children in the United States are treated with CI. The study aimed to examine spoken language outcomes in children undergoing bilateral CI, compared with matched peers undergoing unilateral implantation. In the case-control, frequency-matched, retrospective, cross-sectional, multicenter study at 2 Belgian and 3 Dutch CI centers, 25 children with 1 CI were matched with 25 children with 2 CIs and selected from a retrospective sample of 288 children who underwent CI before the age of 5. Both groups were matched on factors that might influence language development. The factors were divided into auditory, child, and environmental. The primary end point was performance on measures of spoken language comprehension and expression from 2 standardized language tests. The Dutch version of the Reynell Developmental Language Scales (RDLS) was used to measure the receptive language outcome. This standardized language assessment tool is designed for children 1.02 to 6.03 years of age. The expressive counterpart of the Dutch RDLS is the Schlichting Expressive Language Test (SELT), which is given to children 1.09 to 6.03 years of age. The researchers administered the Word Development and Sentence Development SELT subsets orally 3 years after the first CI, between March 20, 2003, and December 8, 2009. Children in the bilateral implantation group had at least 3 months of experience with their second implant. The study found that children undergoing bilateral implantation performed significantly better on both tests compared with those undergoing unilateral implantation. For the RDLS scores, the bilateral group scored significantly better than the unilateral group (mean score, 85.6 vs 76.2, respectively; mean difference 95% confidence interval, 9.4 [0.3-18.6]). With regard to SELT scores, the bilateral group performed significantly better on the Word Development Subscale compared with the unilateral group (mean score, 86.1 vs 70.4, respectively; mean difference 95% confidence interval, 15.7 [5.9-25.4]). The results of the Sentence Development Subscale of the SELT also had the bilateral group outperforming the unilateral group (mean score, 86.8 vs 77.0, respectively; mean difference 95% confidence interval, 9.7 [1.5-17.9]). The researchers also found that a shorter interval between both implantations was related to higher standard scores. Children undergoing 2 simultaneous CIs performed better on the expressive Word Development Test than did children undergoing 2 sequential implantations. The shorter the time interval between the first and second implantations in the bilateral group, the better the results were on the RDLS (β=−0.36 [SE=0.17]; Pearson R=0.40; P=.04), the SELT Word Development Subtest (β=−0.58 [SE=0.21]; Pearson R=0.50; P=.01), and Sentence Development Subtest (β=−0.54 [SE=0.18]; Pearson R=0.53; P=.006). Limitations noted by the authors included that some factors about the study population remained unknown, such as the exact socioeconomic status of the family at the time of testing. The study also focused on short-term results. The researchers noted that the effect of bilateral implantation and the interval between first and second implantations may evolve over time. Whereas studies have shown the benefit of bilateral implantation in children on auditory development, the researchers believe their study is one of the first to demonstrate a positive effect on language scores. “Results from this study carry implications for the clinical treatment of deaf children receiving cochlear implants,” concluded the investigators.