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Effects of round window dexamethasone on residual hearing in a Guinea pig model of cochlear implantation.

AbstractUNLABELLED:
To study electric acoustic stimulation, we have developed a model of guinea pig cochlear implantation via a cochleostomy. Thirty minutes prior to implantation, a hyaluronic acid/carboxymethylcellulose bead, loaded with either dexamethasone or normal saline, was placed upon the round window membrane. Animals that did not receive beads acted as controls. Pure-tone auditory brainstem response thresholds were estimated before and after electrode insertion, and 1 and 4 weeks later. Selected cochlear histology was performed.
RESULTS:
Dexamethasone could be detected in the cochlea for 24 h after cochlear implantation. Thresholds were elevated across frequencies in all animals immediately after surgery. These thresholds recovered completely at and below 2 kHz, and partially at higher frequencies by 1 week after implantation. At 32 kHz, but not the lower frequencies, the presence of dexamethasone had a significant protective effect upon hearing, which increased in magnitude over time. The protection was greatest in difficult implantations where an intractable resistance to electrode insertion was met. There was a persistent foreign body reaction at the site of implantation of saline-treated implanted ears but not in the dexamethasone-treated implanted ears.
CONCLUSION:
Short-term preoperative delivery of dexamethasone through the round window can protect residual hearing during cochlear implantation, especially during technically difficult surgery.
AuthorsDavid P James, Hayden Eastwood, Rachael T Richardson, Stephen J O'Leary
JournalAudiology & neuro-otology (Audiol Neurootol) Vol. 13 Issue 2 Pg. 86-96 ( 2008) ISSN: 1421-9700 [Electronic] Switzerland
PMID18057872 (Publication Type: Journal Article)
Copyright(c) 2007 S. Karger AG, Basel
Chemical References
  • Adrenal Cortex Hormones
  • Dexamethasone
Topics
  • Adrenal Cortex Hormones (pharmacology)
  • Animals
  • Audiometry, Pure-Tone
  • Cochlear Implantation
  • Dexamethasone (pharmacology)
  • Evoked Potentials, Auditory, Brain Stem (physiology)
  • Guinea Pigs
  • Hearing (drug effects)
  • Postoperative Complications
  • Round Window, Ear (drug effects)

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