According to early findings from a multi-center study led by specialists at NYU Langone Medical Center, people with a common form of hearing loss not helped by hearing aids achieved significant improvements in their hearing and understanding of speech with hybrid cochlear implants.
As described in an online article that appeared in the July 7, 2015 edition of the journal The Laryngoscope, researchers at 10 medical centers and private clinics in the United States implanted hybrid cochlear implants into one ear of 50 men and women. All study volunteers had damaged inner-ear hair cells resulting in high-frequency hearing loss, which prevented them from understanding speech, especially in the presence of background noise. All study participants had sufficient low-frequency hearing to perceive some sound, so they were not candidates for a conventional cochlear implant.
A year after receiving the hybrid cochlear implant device, 45 study participants showed overall improvement in their hearing and speech recognition.
“Our study offers early evidence that potentially millions more people with high-frequency hearing loss, who cannot benefit from a hearing aid, could instead possibly benefit from a hybrid cochlear implant,” said lead study investigator J. Thomas Roland, MD, the Mendik Foundation Chairman of the Department of Otolaryngology-Head and Neck Surgery at NYU Langone. Roland, who also serves as co-director of NYU Langone’s cochlear implant program, and has implanted many of the hybrid devices.
The hybrid devices were approved for adults by the US Food and Drug Administration in 2014. Hybrid cochlear implants typically cost about $30,000, and require a surgical procedure.
The researchers explain that the hybrid implant differs from the traditional cochlear implant in that it has a shorter electrode (less than 2 centimeters long) that does not have to be inserted as deeply into the spiral-shaped inner ear, or cochlea. With correct placement of the internal electrode in the inner ear, the hybrid cochlear implant is intended to augment high-frequency hearing via electrical stimulation, while also preserving more residual, natural, low-frequency hearing.
The National Institute on Deafness and Other Communication Disorders estimates that some 26 million American adults between the ages of 20 and 69 suffer from some loss of high-frequency hearing, which makes speech recognition especially difficult.
According to Roland, the loss of high-frequency hearing had caused many of the study participants to fail at work and in social environments because of their inability to hear and understand speech. He said that hearing aids were not an option for them because the sound-amplifying technology could sufficiently raise high-frequency sounds to improve understanding of speech, especially when there was any background noise. Further, the study participants still had some residual low-frequency hearing, so did not qualify as candidates to get a traditional cochlear implant placed in each ear to replace both high- and low-frequency hearing.
According to the study authors, among the study participants, 15 with total loss of high-frequency hearing and moderate loss of low-frequency hearing saw improvements in standard tests of their ability to understand set phrases and sentences read back to them. Their scores for correctly identifying spoken words and phrases rose from a baseline average of 21% before implantation to 67% a year after implantation and activation of their device.
The authors report that for 14 other study participants with severe or total loss of their residual low-frequency hearing, test scores for correctly identifying certain spoken words and phrases improved from 12 percent to 54%, and from 14% to 35%, respectively. Study participants’ hearing was assessed every few months.
The researchers said that adverse events with the device were relatively rare and consisted primarily of mild post-operative dizziness, and ringing sounds in the ear–both of which soon subsided after surgery or after device activation.
Funding support for the nearly four-year-long study was provided by Cochlear Americas of Centennial, Colo, the manufacturer of the Cochlear Nucleus Hybrid implant device used in the study. Roland has served on advisory boards to both Cochlear Americas and Advanced Bionics of Valencia, Calif, another cochlear implant manufacturer. Besides Roland, other researchers involved in this study were Bruce Gantz, MD, at the University of Iowa in Iowa City; Susan Waltzman, PhD, also of NYU Langone; and Aaron Parkinson, PhD, at the University of Washington in Seattle.
More information about the study is available on the NYU Langone Medical Center website.
Source: NYU Langone Medical Center; The Laryngoscope
Photo credits: NYU Langone Medical Center; The Laryngoscope; Cochlear Americas