Sept 2016 Herald Sun
A device that stimulates hearing nerves and slowly releases drugs into the inner ear has been implanted into Australian patients in an experimental world-first trial. Designed by Melbourne scientists and surgeons, the drug-eluting electrode builds on the success of the cochlear implant by dampening the body’s inflammatory response after surgery. It’s anticipated that this will not only increase the hearing device’s effectiveness, but may better preserve the patient’s residual hearing. The anti-inflammatory drugs are encased in specially-designed pockets along the electrode array and slowly released into the inner ear after implantation. Professor Robert Cowan, HEARing Cooperative Research Centre CEO, said delivering the drugs directly to cochlea (the snail like structure in the inner ear) modifies the body’s normal response. “Just like a splinter in your finger; the body creates a wall of tissue to encase any foreign object, with the cochlear implant electrode it creates a sheath of tissue around the device. This is good because it provides a seal against infection, but the thicker the sheath, the more difficult it can be for the electrical current to flow from the surface of the electrodes to the nerve tissue to stimulate it.” For patients this means the device uses more power and requires frequent battery changes. It may also reduce the quality of the hearing a patient acquires as the current that stimulates the nerves is more widely spread.
After more than six years of trials, the devices were implanted in eight patients from The Royal Victorian Eye and Ear Hospital and two from the Royal Institute for Deaf and Blind Children in Sydney. A further 20 patients received the standard cochlear implant for comparison.
“Our initial results showed that there were lower levels of electrical impedance for the patients who got the drug-eluting array and this continues to be the case 12 months after the surgery,” Prof Cowan said. “The drug is controlling the inflammatory response and the way the tissue forms around the cochlea so that we have a reduced electrical requirement, which makes for a longer battery life.” It’s also hoped that the device could assist in preserving more of the patient’s own residual hearing, which can sometimes be reduced by trauma to the cochlea at implantation.
“Many patients have significant residual acoustic hearing and we want to make sure they can retain this while using the cochlear implants. He said their hope was that the device could result in more people considering getting a cochlear implant to manage hearing loss.