Contemporary biological factors in cochlear implantation and hearing preservation

Residual hearing preservation is necessary for deaf patients to experience the full benefits of electro-acoustic stimulation cochlear implants. Hearing preservation is often considered a benchmark of successful atraumatic surgery and cochlear health preservation, making it an important goal of the procedure. The role of inflammatory status in hearing preservation has been empirically supported through the development of surgical protocols featuring corticosteroids. Its role is also inferred though investigations of inner-ear inflammatory responses, or studies of the inflammatory component in auditory pathologies. However, work directly investigating the effect of systemic inflammatory state on their audiological outcomes has never been attempted. A multi-method research strategy consisting of: a murine immunohisto chemical pilot study, a meta-analysis of cochlear implant adverse events, a meta-analysis of factors related to hearing preservation, and a preliminary longitudinal observational clinical outcomes study was implemented. The results from the studies were incorporated into a conceptual framework of the relationship between multiple factors and their effect on outcomes in cochlear implantation. This body of work suggests that cochlear inflammatory state is a significant effector of hearing preservation. It introduces the concept of an individual's systemic inflammatory state having bearings on their clinical outcomes. The consequences of this body of work include: i) suggested modifications to surgical protocols so as to maximise hearing preservation , ii) recommended routine monitoring of a patient's inflammatory state throughout their care pathway, iii) the importance of considering inflammatory state and the timing of a patient's surgery in order to allow for more stratified medicine, iv) a highlighted need for multi-centre collaborations in order to create a more exhaustive model of outcomes in hearing preservation surgery, and v) a need for deeper investigation of the pathophysiology of hearing loss for more guided research on deafness intervention.