Extending the Indications of Cochlear Implantation in Adults with Single-Sided Deafness. A Comprehensive Review

Introduction: Cochlear implantation is a well-established treatment for adults with bilateral postlingual deafness. In recent years, increasing research attention has focused on its use in patients with single-sided deafness (SSD) with or without tinnitus. Restoration of binaural auditory input through cochlear implantation may partially reestablish binaural processing. Methods: We conducted a narrative review of the literature focusing on studies examining the basic mechanisms associated with hearing impairment in SSD, as well as cochlear implantation outcomes in this population, including hearing performance, tinnitus suppression, and quality of life (QoL). We also reviewed comparative studies between cochlear implants (CIs) and alternative hearing devices, along with current candidacy criteria and the challenges associated with cochlear implantation in this patient group. Results: Current evidence suggests that CIs can provide significant benefits in this population, including tinnitus reduction or suppression, improved speech perception in both quiet and noise, enhanced sound localization, and better disease-specific and overall QoL. Furthermore, numerous studies—despite some variability in outcomes—indicate that CIs may offer superior performance compared with alternative options, such as contralateral routing of signals hearing aids (CROS-HAs) and bone-conduction devices, particularly in terms of speech perception, localization, tinnitus control, and aspects of QoL. Nevertheless, appropriate candidacy criteria and key challenges—most notably device non-use—should be carefully considered when evaluating cochlear implantation in this patient population. Conclusions: Further research is required to address these challenges and to advance a more personalized approach to cochlear implantation in individuals with SSD, with the aim of optimizing outcomes and reducing cochlear implant non-use.