In approving Cochlear Ltd.’s Nucleus Hybrid L24 Implant System for use in the United States, the U.S. Food and Drug Administration (FDA) had to balance some serious demonstrable risks against many obvious benefits of the new implant system.
The biggest problem some early users experienced — complete loss of their low-frequency hearing in the implanted ear — might seem to defeat the purpose of the hybrid implant. One of its principal functions, after all, is to preserve and use patients’ remaining natural low-frequency hearing while electronically restoring their lost high-frequency hearing.
The FDA’s decision to approve use of the implant in spite of the problems it observed underscores the growing understanding of the value of hearing implant technology, even when there are problems associated with it.
Cochlear’s Nucleus Hybrid L24 Implant System combines the functions of a cochlear implant and a hearing aid. For lost mid- and high-frequency hearing, the cochlear implant technology — an external microphone and speech processor that picks up sounds from the environment and converts them into electrical impulses — electronically creates sounds patients can understand. For intact low-frequency hearing, the hearing aid portion of the device is inserted into the outer ear canal like a conventional hearing aid and amplifies sounds in the low-frequency range that the patient can hear naturally.
The FDA said in its announcement that a majority of the initial patients it surveyed “reported statistically significant improvements in word and sentence recognition.” But in announcing the approval, the FDA also listed problems experienced by a significant percentage of initial patients it studied. Prior to the procedure, all of the patients had severe-to-profound high-frequency hearing loss but had retained “significant levels of low-frequency hearing.” After the procedure, a large percentage of those patients “developed profound or total low-frequency hearing loss in the implanted ear.”
In other words, rather than being able to use their natural residual low-frequency hearing with the hearing-aid portion of the product as they had hoped, a number of patients effectively lost their low-frequency hearing entirely, in addition to experiencing other “adverse events.” According to the FDA’s news release:
The agency evaluated a clinical study involving 50 individuals with severe to profound high-frequency hearing loss who still had significant levels of low-frequency hearing. The individuals were tested before and after being implanted with the device….Of the 50 individuals participating in the study, 68 percent experienced one or more anticipated adverse events, such as low-frequency hearing loss, tinnitus (ringing in the ear), electrode malfunction and dizziness. Twenty-two developed profound or total low-frequency hearing loss in the implanted ear, six of whom underwent an additional surgery to replace the Nucleus Hybrid L24 Cochlear Implant System with a standard cochlear implant.
With such a large percentage of patients losing rather than using their low-frequency hearing, why did the FDA grant its approval? Because the benefits of restoring the high-frequency hearing so essential for comprehension of speech still outweigh the risks for people who have no other way of understanding speech. “While the risk of low-frequency hearing loss is of concern, the FDA determined that the overall benefits of the device outweigh this risk for those who do not benefit from traditional hearing aids,” the FDA said in its announcement.
The FDA also acknowledged the growing awareness that widespread untreated hearing loss is a public health problem that affects individuals’ health and their productivity in the workforce.
“Hearing loss greatly impacts the education, employment, and well-being of many Americans,” Christy Foreman, director of the Office of Device Evaluation at the FDA’s Center for Devices and Radiological Health, said in the FDA announcement. “This device may provide improved speech recognition for people with this kind of hearing loss, who have limited treatment options.”
There’s an old saying among Silicon Valley entrepreneurs that you want to stay at the “leading edge” of markets and technology while avoiding the “bleeding edge.” The regulators at the FDA trying to balance the risks and rewards in new hearing implant technologies can certainly relate.