Cochlear implant and tinnitus: a narrative literature review and evidence for clinical use

INTRODUCTION: Tinnitus is one of the major complaints in patients with bilateral hearing loss or single-sided deafness (SSD). Several studies describe that cochlear implantation may play a role in tinnitus suppression. Results in the literature are heterogeneous for the role and level of success that Cochlear Implants (CI) plays in tinnitus suppression. The purpose of this review is to summarize all of the significant evidence and outcomes documented as to CI effects on tinnitus perception in unilateral/bilateral CI users and SSD patients, as well as to report on tinnitus findings and fitting strategies currently used to optimize the results for supporting a clear counselling process. EVIDENCE ACQUISITION: A comprehensive literature search was undertaken using the following databases: PubMed, Embase, Cochrane Library, Scopus, CINAHL and Web of Science. Included articles are published through to November 2022 and referenced by relevant literature. The eligible studies and data results were summarized in this narrative review. EVIDENCE SYNTHESIS: The review was organized to deliver a summary of: CI pathophysiologic mechanisms and prognostic factors in- volved in tinnitus suppression; CI outcomes for both unilateral and bilateral implantation in bilateral symmetrical hearing loss, as well as in asymmetrical hearing loss and in SSD patients; the relevant findings concerning CI fitting in managing tinnitus suppression. Finally, the effects of CI on quality of life and psychological status of patients with tinnitus were addressed. CONCLUSIONS: The present review is a targeted contribution to support clinical procedures regarding the applicability and the outcomes of CI in tinnitus treatment. Further studies and specific guidelines are needed to broaden knowledge and understanding in this specific research field.