The future of Cochlear Implants

Researchers presenting at the 25th annual meeting of the American Society for Laser Medicine and Surgery in Orlando, Fla., say optical radiation is able to stimulate hearing function without the limitations of the traditional electrical stimulation.

Cochlear implant.
Credit: Medical illustrations by NIH, Medical Arts & Photography Branch.

Agnella D. Izzo, from Northwestern University in Chicago, presented the data. She explains cochlear implants are for people who have hearing loss due to damage to their sensory receptors. However, their auditory nerve fibers are still alive. The implants work by bypassing normal inner ear function and applying electrical current directly to the nerve fibers in the cochlea.

In theory, the implant should transfer the electrical impulses to distinct groups of nerve fibers, and stimulation of one electrode should not affect the patient's brain response to stimulation applied to other electrodes. However, in reality, these interactions do occur, and the result is often harmful.

To look for an alternative to the electrical stimulation, the research team applied laser stimulation to the auditory cells of gerbils. They say results showed optical radiation was a safe method to stimulate the nerve cells with better selectivity. In addition, the optical stimulation, Izzo says, should allow for better reception of voice and music by the patient.

Researchers say their long-term goal is to design and build optical cochlear implants with improved spatial selectivity for stimulation.

By Amanda Jackson