Evaluation of Intracochlear Trauma Caused by Insertion of Cochlear Implant Electrode Arrays through Different Quadrants of the Round Window

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Cochlear implants (CIs) represent a well-established treatment for severe and profound bilateral hearing loss. The development ofCIs in the last 30years is consideredoneof the milestones ofmodernmedicine, and, to date, the outcomes of CIs have been remarkable and superior to those of any other type of neural prosthesis [1]. These results have encouraged the expansion of the selection criteria for CIs [2].Therefore, the number of candidates with significant residual hearing who are eligible to receive CIs has increased, fostering several studies on the preservation of postoperative residual hearing in these patients. Intracochlear trauma during CI-related surgical interventions is one of the factors associated with residual hearing loss [3–5]. Previous studies have highlighted the possibility of electrode array insertion using atraumatic surgical techniques, which have been designated as soft surgeries [4, 6–9].

Among the steps involved in soft surgeries, electrode array insertion is the most frequently studied. CI arrays can be inserted via cochleostomy or through the round window (RW). According to Banfai [10], RW was the first choice of Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 236364, 9 pages http://dx.doi.org/10.1155/2015/236364 2 BioMed Research International route for CI electrode array insertion. However, with the development of longer, thicker, and less flexible electrodes, insertion through RW became difficult and necessitated cochleostomy. Over the last few years, the development of thinner and more flexible electrodes has again enabled insertion through RW[11].The possibility of electrode array insertion via these two distinct routes stimulated further comparative studies [12–15]. Numerous studies on cochleostomy have been conducted to determine any variations in intracochlear trauma according to its location. However, to date, no studies have evaluated differences in the degree of intracochlear trauma caused by electrode array insertion through different quadrants of the RWmembrane.

Therefore, this study was conducted to determine differences in intracochlear trauma caused by CI electrode array insertion through the anterosuperior and anteroinferior quadrants of the RWmembrane.