title: Insertion forces and intracochlear trauma in temporal bone specimens implanted with a straight atraumatic electrode array.
abstract: The aim of the study was to evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones, and post-implantation histologic evaluation of the samples to determine whether violation of intracochlear structures is related to insertion forces. In order to minimize intracochlear trauma and preserve residual hearing during cochlear implantation, knowledge of the insertion forces is necessary. Ten fresh frozen human temporal bones were prepared with canal wall down mastoidectomy. All samples were mounted on a one-axis force sensor. Insertion of a 16-mm straight atraumatic electrode was performed from different angles to induce "traumatic" insertion. Histologic evaluation was performed in order to evaluate intracochlear trauma. In 4 of 10 samples, dislocation of the electrode into scala vestibuli was observed. The mean insertion force for all 10 procedures was 0.003 ± 0.005 N. Insertion forces measured around the site of dislocation to scala vestibuli in 3 of 4 samples were significantly higher than insertion forces at the same location of the cochleae measured in samples without trauma (p < 0.04). Mean force during the whole insertion process of the straight atraumatic electrode is lower than reported by other studies using longer electrodes. Based on our study, insertion forces leading to basilar membrane trauma may be lower than the previously reported direct rupture forces.
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany. mmirsalehi@gmail.com.|Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. mmirsalehi@gmail.com.
authors.forename: Marjan
authors.identifier: http://orcid.org/0000-0002-9952-5653
authors.initials: M
authors.lastname: Mirsalehi
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Rau
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.|Cochlear Ltd., Sydney, Australia.
authors.forename: Lenka
authors.initials: L
authors.lastname: Harbach
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Hügl
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.|Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Saleh
authors.initials: S
authors.lastname: Mohebbi
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.|Cluster of Excellence Hearing4all, Hannover Medical School, Hanover, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hanover, Germany.|Cluster of Excellence Hearing4all, Hannover Medical School, Hanover, Germany.
authors.forename: Omid
authors.initials: O
authors.lastname: Majdani
mesh_terms: D001489:Basilar Membrane / Q000293:injuries / Q000473:pathology; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods; D003054:Cochlear Implants / Q000009:adverse effects*; D006801:Humans; D007431:Intraoperative Complications / Q000473:pathology / Q000517:prevention & control; D008953:Models, Anatomic; D012421:Rupture / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D013701:Temporal Bone / Q000473:pathology / Q000601:surgery
keywords: Cochlear implants; Insertion forces; Intracochlear trauma; Straight atraumatic electrode array