Methods of Hearing Preservation during Cochlear Implantation

Abstract

Introduction Recent advances in surgical techniques and electrode design have made residual hearing preservation during cochlear implantation (CI) possible, achievable, and desirable. Objectives The objective of this study was to review the literature regarding methods used for hearing preservation during CI surgery. Data Synthesis We performed a search in the LILACS, MEDLINE, SciELO, PubMed databases, and Cochrane Library, using the keywords CI, hearing preservation, CI electrode design, and CI soft surgery. We fully read about 15 studies that met the criteria described in “study selection”. The studies showed that several factors could contribute to possible cochlear damage during or after CI surgery and must be kept in mind; mechanical damage during electrode insertion, shock waves in the perilymph fluid due to implantation, acoustic trauma due to drilling, loss of perilymph and disruption of inner ear fluid homeostasis, potential bacterial infection, and secondary intracochlear fibrous tissue formation. The desire to preserve residual hearing has led to the development of the soft-surgery protocols with its various components; avoiding entry of blood into the cochlea and the use of hyaluronate seem to be reasonably supported, whereas the use of topical steroids is questionable. The site of entry into the cochlea, electrode design, and the depth of insertion are also important contributing factors. Conclusion Hearing preservation would be useful for CI patients to benefit from the residual low frequency, as well as for the children who could be candidate for future regenerative hair cell therapy.

Advances in Surgical and Anesthetic Techniques for Cochlear Implantation

“…3. Scala tympani electrode insertion and avoidance of injury of the osseous spiral lamina and basilar membrane [65].…”

“…Corticosteroid can be administrated during CI surgery aiming at hearing preservation [65]. Perioperative corticosteroids can be used either systemic, intratympanic, or intracochlear.…”

Electric and Acoustic Stimulation in Cochlear Implant Recipients with Hearing Preservation

“…16 There is some suggestion of cytotoxicity from its use with high concentrations and intracochlear administration, 71 but at lower concentrations no adverse effects have been seen when incorporated into soft insertion techniques. 72 The ultimate goal of the advances described earlier is the ability to preserve all residual hearing in all patients undergoing cochlear implantation. Postoperative hearing preservation has been reported in a high number of EAS recipients, but many experience some change in residual hearing thresholds.…”

A maradványhallás megőrzésének lehetőségei cochlearis implantáció során Nucleus CI532 Slim Modiolar elektródasorral

“…A jelen cikk tárgyát képező Nucleus CI532-es elektróda a perimodiolaris csoport tagja [11]. A csont szükséges mértékű elfúrásához minden esetben 1 mm átmérőjű gyémántfúrót használunk lassú fordulatszámon, ezzel elkerülve a fúrás során keletkező hang-és hőártalmat [13,14]. Az endosteum megnyitása előtt, annak felszínére szteroidtartalmú oldatot vagy nátrium-hialuronát-tartalmú készítményt helyezhetünk.…”

“…A második jelentősebb csoportot az elektródasor minimális traumát okozó bevezetése képezi. Ebben szintén számos tényezőnek lehet meghatározó szerepe, mint például: (1) az elektróda bevezetése során keletkező közvetlen trauma; (2) az implantáció kapcsán a perilympha folyadéktérben kialakuló nyomáshullám hatása; (3) a fúró által okozott vibráció, hangártalom, esetleg hőtrauma; (4) perilymphavesztés; (5) a belső fül folyadéktereinek homeosztázisában létrejövő változások; endolymphaticus hydrops kialakulása; (6) a csiga lumenének késői fibroticus, csontos átalakulása [13,14]. Az elektródasor hossza és keresztmetszete szintén korlátozhatja a posztoperatívan elérhető residualis hallás megőrzését [15].…”