A Closer Look at Scar Tissue Formation in Cochlear Implant Patients

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March 1, 2013 — Cochlear implants have helped thousands of people living with hearing loss regain some hearing and allowing them to communicate and participate in life. But surgeons and researchers believe that cochlear implants (CIs) can work even better if the scar tissue associated with implanting the CI electrode in the inner ear can be reduced or treated.

A cochlear implant consists of an external speech processor that picks up sound from the environment with a small microphone, and a transmitter/receiver that receives signals from the speech processor and transmits them as electrical signals to a thin, filamentous electrode array that is surgically threaded into the cochlea. The array has several electrodes or contact points along its length that deliver electrical impulses to spiral ganglion neurons in the snail-shaped cochlea. The auditory nerve carries the signals to the brain where they are translated into different frequencies of sound.

The American Hearing Research Foundation is funding Esperanza Bas Infante, PhD, an associate scientist at the University of Miami who is investigating how and why scar tissue forms along the cochlea after the electrode array is implanted. “When anything is surgically implanted in the body, there is an inflammatory response, which can lead to the formation of tough, fibrotic scar tissue,” Dr. Bas says. “If we can figure out how to interfere with the formation of scar tissue along the array, which happens in some people after cochlear implantation, it will improve the efficacy of the CI and the quality of life of the patient.” Scar tissue can also be a real problem if a CI fails to work properly and needs to be replaced through a second surgery. The AHRF grant is for $20,000 to support research for one year.

Dr. Bas’s research will focus on the molecular mechanisms behind fibrous tissue and bone formation (another form of scar tissue) that can occur after cochlear electrode placement in mice. Wound healing is a complex process involving a cascade of immune and chemical responses with scar tissue formation being one possible outcome. By better understanding this process, which is the aim of her AHRF grant, Dr. Bas hopes to then look at ways the immune response can be mediated using different factors to control scar tissue formation in the cochlea. To see a video of Dr. Bas talking about her research, click here.