Hearing and Structure Preservation Via ECochG

Cochlear implantation is a highly effective method of rehabilitating hearing in individuals with severe to profound hearing loss. One current hurdle to optimising hearing outcomes following cochlear implantation is the unavoidable trauma caused to the inner ear during implant surgery. This damage can mean residual hearing that would remain valuable following implantation is lost. Various approaches have been trialed to preserve hearing during implantation surgery, modifying implantation technique and administering steroids. Electrocochleography (ECochG) is a monitoring technique that can be used during electrode insertion to record inner ear structural integrity and function. The PRESERVE trial is an international, multi-centre, randomised controlled trial. The trial will randomly allocate adult cochlear implant recipients to undergo implantation surgery either with ECochG-guidance, or via the standard approach without guidance. Participants will be blinded, meaning they will not know which group they will be allocated to. Where ECochG is used, evidence of damage during insertion detected with the monitoring will trigger the surgeon to follow a corrective pathway. All other aspects of surgery and post operative care will follow standard clinical pathways for both groups. Participants will have their natural hearing measured preoperatively, and 3- and 6-months following implant activation. The change in natural hearing thresholds at different frequencies, and the degree of hearing preservation will then be calculated and compared between the standard surgery and ECochG-guided group. Using their cochlear implant, understanding of speech will also be measured and compared between groups. In addition, participants will undergo a second CT scan following implantation surgery, and this will be compared to the routine pre-operative imaging to assess both the location of the implant electrode, and structural preservation of the cochlear. Throughout the study participants will remain under the care of their routine medical team.