title: Evaluation of the Relationship between the NRT-Ratio, Cochlear Anatomy, and Insertions Depth of Perimodiolar Cochlear Implant Electrodes.
abstract: The position of the cochlear implant electrode array within the scala tympani is essential for an optimal postoperative hearing benefit. If the electrode array changes in between the scalae intracochlearly (i.e., from scala tympani to scala vestibuli), a reduced auditory performance can be assumed. We established a neural response telemetry-ratio (NRT-ratio) which corresponds with the scalar position of the electrodes but shows within its limits a variability. The aim of this study was to determine if insertion depth angle or cochlea size influences the NRT-ratio. The intraoperative electrophysiological NRT data of 26 patients were evaluated. Using a flat panel tomography system, the position of the electrode array was evaluated radiologically. The insertion depth angle of the electrode, the cochlea size, and the NRT-ratio were calculated postoperatively. The radiological results were compared with the intraoperatively obtained electrophysiological data (NRT-ratio) and statistically evaluated. In all patients the NRT-ratio, the insertion depth angle, and the cochlea size could be determined. A significant correlation between insertional depth, cochlear size, and the NRT-ratio was not found. The NRT-ratio is a reliable electrophysiological tool to determine the scalar position of a perimodiolar electrode array. The NRT-ratio can be applied independent from insertion depth and cochlear size.
authors.affiliation: Department of Otolaryngology, ukb, 12683 Berlin, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Mittmann
authors.affiliation: Department of Radiology and Neuroradiology, ukb, 12683 Berlin, Germany.
authors.forename: Grit
authors.initials: G
authors.lastname: Rademacher
authors.affiliation: Department of Radiology and Neuroradiology, ukb, 12683 Berlin, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Mutze
authors.affiliation: Department of Otolaryngology, University of Freiburg, 79106 Freiburg im Breisgau, Germany.
authors.forename: Frederike
authors.initials: F
authors.lastname: Hassepass
authors.affiliation: Department of Otolaryngology, ukb, 12683 Berlin, Germany.
authors.forename: Arneborg
authors.initials: A
authors.lastname: Ernst
authors.affiliation: Department of Otolaryngology, ukb, 12683 Berlin, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Todt
mesh_terms: D003051:Cochlea / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003054:Cochlear Implants; D055724:Electrophysiological Phenomena; D005260:Female; D006801:Humans; D008297:Male; D011859:Radiography
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