A safety evaluation of dexamethasone-releasing cochlear implants: Comparative study on the risk of otogenic meningitis after implantation

Abstract

Conclusion: Dexamethasone released from a cochlear implant seems not to enhance the risk for postoperative infections. Objective: Dexamethasone has a positive impact on hearing preservation for electric acoustic stimulation (EAS). Due to their antiproliferative and immunosuppressive properties, steroids may enhance the risk of postoperative infections. A comparative study was performed to evaluate the risk of pneumococcal meningitis after implantation of dexamethasone-eluting cochlear implants. Methods: Thirty guinea pigs were implanted with non-eluting (n = 15) or dexamethasone-eluting (n = 15) cochlear implant electrode dummies. After 5 weeks, animals were exposed to a virulent strain of Streptococcus pneumoniae. The two groups were compared based on the meningitis rate. Animals were observed for 5 days for signs of meningitis. Meningitis was verified by clinical outcome as well as by pleocytosis and presence of bacteria in cerebrospinal fluid. Results were confirmed by histological examination of brains and cochleae, clinical findings and culture. Results: There was no significant difference in meningitis risk between the two groups. In the group with non-eluting implants, 3 of 15 animals developed meningitis, while in the group with dexamethasone-eluting implants 4 of 15 showed signs of meningitis. In this study dexamethasone-releasing implants did not significantly increase the risk of postoperative pneumococcal otogenic meningitis.

Keywords::

• Electric and acoustic stimulation
• EAS
• residual hearing
• pneumococcal meningitis
• Streptococcus pneumoniae

Acknowledgments

We gratefully acknowledge Dr Jane M. Opie (Medical Communications Writer at MED-EL GmbH Innsbruck) for medical writing assistance following the preparation of this manuscript. The authors wish to thank Prof. Dr med. Uwe Ködel, Department of Neurology, Klinikum Großhadern, LMU Munich, Germany, for his advice in this research project. We also thank Prof. Dr Sven Hammerschmidt, University of Greifswald, Greifswald, Germany, for providing the pneumococcal strain. This work was supported by a MED-EL research grant (MED-EL GmbH Innsbruck) and Carolyn Garnham is gratefully acknowledged for her support.

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