Promising results have been reported from a world-first study of cochlear implant electrodes designed to not only stimulate hearing nerves but also to slowly release drugs into the inner ear.

HEARing Cooperative Research Centre (HEARing CRC) CEO Professor Robert Cowan said research using an electrode array (pictured right) that slowly releases anti-inflammatory drugs into the cochlea following cochlear implantation could lead to future benefits for cochlear implant users.

“The beauty of this approach is that it is based on use of the standard cochlear implant electrode array inserted into the inner ear that delivers sound sensations to the brain via the electrical stimulation of hearing nerve cells,” Prof. Cowan said.  “Research with our partners at the University of Wollongong’s ARC Centre of Excellence for Electromaterials Science had confirmed the feasibility of using a passive diffusion of drug from the electrode surface as a means of drug delivery to the cochlea over an extended period of up to 4-6 weeks.

“Based on this work, the cochlear implant electrode array used in the research study was modified to slowly release a cortico-steroid after implantation.  This drug is intended to reduce inflammation and the growth of fibrous tissue around the electrode array triggered by the body’s immune response.”

After completing extensive biosafety, surgical and pharmokinetic studies, HEARing CRC researchers progressed to a study of the experimental electrode in ten adult patients, eight at the Royal Victorian Eye and Ear Hospital in Melbourne (RVEEH) and two at the Royal Institute for Deaf and Blind Children – Sydney Cochlear Implant Clinic (SCIC).  ENT surgeons Professor Rob Briggs and Professor Catherine Birman reported no compromise in surgical insertion characteristics with the experimental array.  Initial results confirm lower electrical impedance levels for the drug-eluting array patients, as compared with control groups from both clinics.  Impedance levels continue to remain lower 12 months post-implantation.

“The suppression of the inflammatory reaction in the cochlea following electrode insertion is likely responsible for these lower impedance levels and may potentially contribute to preservation of an implant user’s residual hearing abilities when combined with slimmer electrode designs and newer surgical techniques,” Prof. Cowan explained.

“Hearing preservation is important, as many candidates for cochlear implants have significant residual acoustic hearing, and want to be assured that they can use their residual acoustic hearing together with their cochlear implants.  Our hope is that this breakthrough will result in more people now considering cochlear implants as a viable way to manage their hearing loss”.

“This drug-eluting electrode research has been made possible through the collaboration of Cochlear, the RVEEH, the RIDBC-SCIC, University of Melbourne and University of Wollongong as members of the HEARing CRC, supported through the Commonwealth Governments CRC Programme Prof. Cowan stated.

“The HEARing CRC collaboration has contributed to commercial cochlear implant technologies that are now in world-wide use, as well as fitting technologies for both cochlear implants and hearing aids, helping to maintain Australia’s preeminent international standing in hearing research and service delivery.”

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