title: Effects of sustained release dexamethasone hydrogels in hearing preservation cochlear implantation.
abstract: It has been shown that glucocorticoids reduce the hearing threshold shifts associated with cochlear implantation. Previous studies evaluated the administration of glucocorticoids immediately before surgery or the repeated pre- or perioperative systemic application of glucocorticoids. The aim of this study was to evaluate the effects of a sustained release dexamethasone hydrogel in hearing preservation cochlear implantation. To address this issue, a guinea pig model of cochlear implantation was used. 30 normal hearing pigmented guinea pigs were randomized into a group receiving a single dose of a dexamethasone/poloxamer407 hydrogel one day prior to surgery, a second group receiving the hydrogel seven days prior to surgery and a control group. A silicone cochlear implant electrode designed for the use in guinea pigs was inserted to a depth of 5 mm through a cochleostomy. Compound action potentials of the auditory nerve (frequency range 0.5-32 kHz) were measured preoperatively, directly postoperatively and on postoperative days 3, 7, 14, 21 and 28. Following the last audiometry, temporal bones were harvested and histologically evaluated. Dexamethasone hydrogel application one day prior to surgery resulted in significantly reduced hearing threshold shifts at low, middle and high frequencies measured at postoperative day 28 (p < 0.05). Application of the hydrogel seven days prior to surgery did not show such an effect. Dexamethasone application one day prior to surgery resulted in increased outer hair cell counts in the cochlear apex and in reduced spiral ganglion cell counts in the basal and middle turn of the cochlea, a finding that was associated with a higher rate of electrode translocation in this group. In this study, we were able to demonstrate functional benefits of a single preoperative intratympanic application of a sustained release dexamethasone hydrogel in a guinea pig model of cochlear implantation.
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Clemens
authors: C
authors: Honeder
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Chengjing
authors: C
authors: Zhu
authors: Department of Pathobiology, Institute of Anatomy, Histology and Embryology, University of Veterinary Medicine Vienna, Vienna, Austria.
authors: Hanna
authors: H
authors: Schöpper
authors: Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria.
authors: Julia Clara
authors: JC
authors: Gausterer
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Manuel
authors: M
authors: Walter
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Lukas David
authors: LD
authors: Landegger
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Nodir
authors: N
authors: Saidov
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
authors: Dominik
authors: D
authors: Riss
authors: Department of Biomedical Research, Medical University of Vienna, Vienna, Austria.
authors: Roberto
authors: R
authors: Plasenzotti
authors: Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria.
authors: Franz
authors: F
authors: Gabor
authors: Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria. Electronic address: christoph.arnoldner@meduniwien.ac.at.
authors: Christoph
authors: C
authors: Arnoldner
mesh_terms: D000200:Action Potentials; D000287:Administration, Topical; D000818:Animals; D001299:Audiometry; D001309:Auditory Threshold / Q000187:drug effects; D003051:Cochlea / Q000503:physiopathology; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003692:Delayed-Action Preparations; D003907:Dexamethasone / Q000008:administration & dosage*; D004566:Electrodes; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005938:Glucocorticoids / Q000008:administration & dosage; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000473:pathology*; D034381:Hearing Loss / Q000503:physiopathology; D006320:Hearing Tests; D020100:Hydrogels / Q000737:chemistry*; D013136:Spiral Ganglion / Q000503:physiopathology; D013256:Steroids / Q000008:administration & dosage*
chemical_list: D003692:Delayed-Action Preparations; D005938:Glucocorticoids; D020100:Hydrogels; D013256:Steroids; D003907:Dexamethasone
keywords: Cochlear implantation; Dexamethasone; Glucocorticoids; Guinea pig; Hearing preservation; Poloxamer407