A Systematic Review to Determine The Effectiveness of Using Amplification in Conjunction With Cochlear Implantation

Abstract

Background: The question regarding the use of amplification with implantation is timely and relevant in today's clinical settings where an increased number of adults with measurable hearing are receiving cochlear implants due to the expanding implant criteria, especially among individuals seeking bilateral implantation. Purpose: To review the evidence available to answer the clinical question: “Does amplification in the ear opposite of a cochlear implant provide improved communication function for adult users?” Research Design: A systematic review of the evidence that met the search criteria related to the use of amplification in adult implant users. All types of experiments were included with the exception of expert opinion. This systematic review ranked the levels of evidence related to these studies and distinguished the levels of evidence from judgments about the grade and strength of recommendations for the stated clinical question. Study Sample: Fifty-two articles were initially reviewed with a final 11 articles meeting the search criteria and identified for in-depth analysis. Data Collection and Analysis: Several electronic databases and textbooks were searched to locate the evidence related to bimodal stimulation. Each article was reviewed using a check sheet and assigned a ranking for level of evidence (Levels 1–6) based on the type of research design that was used and a grade of evidence (A–D) based on the quality, relevance, and extensiveness of the study. Finally the level and grade were collapsed into only three categories to indicating the strength of the recommendations coming from each study and were classified as either strong (I), moderate (II), or weak (III). Results: Several trends about bimodal stimulation were observed, which include (1) significantly better speech understanding in the bimodal condition for many participants; (2) in noise, the largest bimodal benefits in speech recognition; (3) variable findings on localization tasks; and (4) overall significant improvement in functional ability based on self-assessments. The preponderance of evidence received grades of B or C. Conclusions: The evidence available indicates “moderate” (II) strength in support of bimodal stimulation for adult implant users. Clinicians should encourage their clients to consider bimodal fittings. Additional research is needed about optimal time frame for introducing bimodal fittings as well as establishing a clinical profile of patients who may benefit most from this intervention compared to bilateral implantation.