Extended use of systemic steroid is beneficial in preserving hearing in guinea pigs after cochlear implant

Abstract

Conclusion: Seven-day administration of systemic steroids was more effective in preserving hearing for 12 weeks after cochlear implantation (CI) than a 3-day delivery.

Objectives: To determine the effectiveness of extended delivery of systemic steroids to preserve hearing in guinea pigs after CI.

Methods: Dexamethasone (4 mg/ml) was delivered parenterally via a mini-osmotic pump for either 3 or 7 days. A dummy CI electrode was inserted via cochleostomy approach in 8-week-old guinea pigs. Auditory thresholds were assessed from tone burst auditory brainstem responses (2, 8, 16, 24, and 32 kHz) at 1 day prior to CI, and 1, 4, and 12 weeks after implantation. Histologic evaluation of the cochleae was carried out.

Results: No differences were observed in hearing thresholds among groups before CI. Significant hearing preservation was achieved at 8, 16, 24, and 32 kHz only in the 7-day infusion group compared with the control group at 1 week after CI. The same trend was maintained at 4 weeks (16, 24 kHz) and 12 weeks (16, 24, and 32 kHz). Histologic review of the 7-day infusion group revealed less fibrosis and ossification in the scala tympani and the preservation of more spiral ganglion cells, compared with the control group.

Keywords:

• Cochlear implant
• hearing loss
• steroid

Acknowledgements

We thank Cochlear^® for providing us experimental dummy electrodes for this study.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

This study was supported by grant [04-2013-0610] from the Seoul National University Hospital Research Fund.