Effect of cochlear implantation on language development and assessment of the quality of studies in this field: A systematic review

Background: Cochlear implantation (CI) is an achievement that facilitates the acquisition of language skills in deaf children throughout the world. The use of this technology has a positive effect on all components of language acquisition (syntax, semantic, pragmatic, etc.). However, this positive impact is influenced by various factors. Understanding the strengths and weaknesses of studies on the development of language abilities can help improve these studies. Consequently, in the future, it will lead to the improvement of language rehabilitation in these children. Limited studies on children with CI in have been done so far. This article summarized the outcomes of scientific articles on the clinical efficacy of CI on Persian speaking children. This study also provided a clear picture of these studies by examining the quality of their methodologies and tools. Methods: Articles indexed in Google Scholar, Web of Science, Medline, Scopus and Iranian databases (Danesh Gostar, Magiran, and SID) were searched using keywords "language," "Cochlear implant", "Persian/ Farsi" in English and Persian languages with "and/or". Original articles investigated on children younger than 13 years old with hearing impairment and CI were included. Results: Five hundred and twenty-three articles were found based on the keywords. Among all of these, 485 were excluded due to the title and the abstract; we selected 38, of which 24 were repeated. Finally, 14 articles remained. We reviewed the articles based on the preferred reporting items for systematic review and meta-analysis (PRISMA) and checklist and Grading of Recommendations, Assessment, Development, and Evaluations (GRADE). Conclusion: Similar to international studies, Persian speaking children with CI have slower language development than their peers with normal hearing, but they are better than their peers who use hearing aids. The results of reviewing on quality of the articles showed that the studies could not meet reasonable quality because of the lack of a standard test in different aspects of Persian language and the absence of patients’ databanks. These results also can be used by other nationalities that recently have started surveys on children with CIs.