Cochlear implant and inflammation reaction: Safety study of a new steroid-eluting electrode.
Dexamethasone is a common anti-inflammatory agent added to cochlear implants to reduce hearing loss due to electrode insertion trauma. We evaluated the safety of eluting silicone rods containing 10% dexamethasone in a Guinea pig model. Animals were implanted with a dexamethasone eluting silicone electrode (DER) or with a non-eluting electrode (NER). The control group only underwent a cochleostomy (CS). Prior to implantation and during the two weeks following implantation, the hearing status of the animals was assessed by means of Compound Action Potentials (CAPs) with an electrode placed near the round window. Two weeks after implantation, the mean click threshold shifts were 1 dB ± 10 dB in the DER group, 10 dB ± 10 dB in the NER group and -4 dB ± 10 dB in the control group. After two weeks the bullae of each animal were extracted to verify the presence of macrophages, the percent of tissue growth in the scala tympani and the tissue sealing around cochleostomy. Silicone electrodes samples were also explanted and examined for bacterial infection. Neither bacterial infection nor enhanced number of macrophages were observed. A limited, but not significant, tissue growth was found in the scala tympani between the experimental and the control group. The data suggest that, in the Guinea pig model, the use of DER is apparently safe as an anti-inflammatory slow-release additive to the cochlear implant.
Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy. Electronic address: laura.astolfi@unipd.it.
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Astolfi
Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy. Electronic address: edi.simoni@unipd.it.
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Simoni
ENT - Head and Neck Surgery Department, F. Tappeiner Hospital, Via Rossini 5, 39012, Merano, BZ, Italy. Electronic address: nadia.giarbini@asbmeran-o.it.
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Giarbini
Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy. Electronic address: grdptr@unife.it.
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Giordano
Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, 91120, Jerusalem, Israel. Electronic address: micaela.pannella@gmail.com.
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Pannella
ENT & Audiology Department, University Hospital of Ferrara, Via Aldo Moro 8, 44124, Cona, Ferrara, Italy. Electronic address: sdh1@unife.it.
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Hatzopoulos
Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy; ENT Surgery - Department of Neurosciences, University of Padua, Via Giustiniani 2, 35129, Padua, Italy. Electronic address: alessandromartini@unipd.it.
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Martini
D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000494:pharmacology; D001309:Auditory Threshold; D003051:Cochlea / Q000601:surgery; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants / Q000009:adverse effects*; D003907:Dexamethasone / Q000008:administration & dosage* / Q000494:pharmacology; D016503:Drug Delivery Systems; D004566:Electrodes; D004567:Electrodes, Implanted; D016057:Evoked Potentials, Auditory, Brain Stem; D005355:Fibrosis; D006168:Guinea Pigs; D006309:Hearing; D034381:Hearing Loss; D008264:Macrophages / Q000378:metabolism; D012405:Round Window, Ear / Q000601:surgery; D012533:Scala Tympani / Q000502:physiology / Q000601:surgery*; D012828:Silicones / Q000737:chemistry
D000305:Adrenal Cortex Hormones; D000893:Anti-Inflammatory Agents; D012828:Silicones; D003907:Dexamethasone
Anti-inflammatory addition; Bacterial infection; Cochlear implant; Cochleostomy; Drug delivery; Fibrosis