Cochlear Implants' Performance Not Affected By Amount Of Hearing Loss In The Implanted Ear

There is growing evidence that the amount of hearing in an ear priorto surgery is unrelated to a patient's ability to interpret speechusing an implant, says Howard W. Francis, M.D., lead author of thestudy and an associate professor of otolaryngology-head and necksurgery. Therefore, the better-hearing ear could be saved for thecontinued use of a hearing aid or future technology to complement acochlear implant, Francis says.

Reporting in the August issue of the journal Ear and Hearing,Francis and colleagues compared patients with no residual hearing,patients with some residual hearing in one ear and patients with someresidual hearing in both ears. The patients' ability to interpretsounds and speech was measured before and after cochlear implantsurgery.

Patients with residual hearing in one or both ears prior tosurgery scored significantly higher on the speech perception testsfollowing surgery, even when the implanted ear was profoundly deafprior to surgery. The researchers also noted that patients' ability tointerpret speech in a noisy environment increased dramatically overtime in proportion with the amount of residual hearing in thenon-implanted ear.

"In cases where even a small amount of hearing ability remainsin one ear, the central nervous system is better able to integrateauditory information with a cochlear implant, and equally so fromeither ear," Francis says. "This speaks to the brain's circuitry andits ability to interpret electrical signals generated by the implanteven in the presumably more degenerated ear."