NEW YORK (Reuters Health) – Adult patients who receive bilateral cochlear implants (BiCIs) two years apart hear as well as patients who receive the implants simultaneously, according to a multicenter randomized trial.
These findings suggest that patients who already received a single cochlear implant and then receive a second implant two years later “can acquire the same benefits as simultaneously implanted bilateral cochlear implant users,” first author Dr. Veronique J. C. Kraaijenga, of University Medical Center Utrecht, the Netherlands, told Reuters Health by email.
Bilateral implants recreate the normal “binaural” hearing system using both ears. The benefits compared with a single implant include better hearing in noisy environments and better localization of the source of a sound, which can be particularly important in situations such as navigating in traffic, Dr. Kraaijenga noted.
In the last decade, evidence from cohort studies has suggested that patients appear to derive more benefit from bilateral implants compared with having an implant in only one ear. But no randomized trial had compared the two approaches in adults, so despite the apparent benefits, bilateral cochlear implantation is still not reimbursed in many countries, including the Netherlands, Dr. Kraaijenga explained.
“With the results of this study, we hope to convince the Dutch insurance companies that reimbursing bilateral cochlear implants is beneficial even when patients have already received a first implant,” she said.
In the study, conducted between 2010 and 2012, 38 individuals with postlingual onset of hearing loss and no previous cochlear implant were randomly assigned to receive simultaneous implants (19 individuals; median age, 52 years) or sequential implantation with a two-year interval between the surgeries (19 individuals; median age, 54).
All participants underwent hearing tests and also completed questionnaires to assess self-reported benefits in hearing and quality of life. Three participants in the sequential group did not receive the second implant and were unavailable for follow-up.
One year after receiving a second cochlear implant, both groups performed equally well for nearly all objective and subjective hearing tests, the researchers report in JAMA Otolaryngology-Head and Neck Surgery, online June 22.
“The sequential BiCI group did not need a longer follow-up to reach the same level of speech perception as the simultaneous BiCI group,” they noted.
An analysis of hearing performance of sequential group participants over the course of the study showed that all individuals performed significantly better on hearing tests in understanding speech in a noisy setting and localizing the source of a noise one year after the second implant than they had in previous years. This improvement was consistent with most of the patients’ own subjective reports (on questionnaires) of how well they were hearing.
One surprising finding, said Dr. Kraaijenga, was that participants in the simultaneous group continued to improve over the three-year period after implantation in perceiving speech from noise from spatially separated sources. This increase might be the result of “the squelch effect,” an advantage of binaural hearing, in which the brain is able to process sounds and suppress interfering noises while focusing on the speech of one person.
“It would be very useful to see whether the sequential group will also show such a growth” over a longer follow-up, she said.
“Overall, the results here are good news for people with significant hearing loss and further indicate how powerful cochlear implants are at improving their quality of life,” Dr. Timothy Hullar, head of the cochlear-implant program at Oregon Health and Science University, Portland, told Reuters Health by email.
Simultaneous implantation means only one surgery instead of two, and may help the implants provide more benefit earlier, noted Dr. Hullar, who was not involved with the current research. The trade-off, however, is that “simultaneous surgeries are longer and more taxing on the surgeon, and appointments with the audiologist are more intensive as well, because twice as much must be done,” he said.
“This paper indicates that adults do not seem to gain a benefit in understanding speech or localizing sound after simultaneous as opposed to sequential implantation, at least up to a two-year delay between surgeries,” said Dr. Hullar. “This increases our ability to care for adult patients with hearing loss, giving us more options for success when counseling and planning for patient surgeries.”
Advanced Bionics sponsored the study and provided the second cochlear implant to all study centers. Some of the authors reported receiving nonrestricted grants from Advanced Bionics or other cochlear implant makers.
SOURCE: http://bit.ly/2tjpHSZ
JAMA Otolaryngol Head Neck Surg 2017
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