Technologically, cochlear implants have taken giant strides (2003)

As the number of cochlear implant wearers continues to increase (see cover story), all three implant manufacturers are bringing an array of enhanced new products to market. These products are part of a rushing stream of innovations that is expanding cochlear implant candidacy, improving performance, and facilitating programming and follow-up care. “Back in the early 80s, we were thrilled when a cochlear implant patient heard a sound, even without understanding speech,” says Patricia Chute, AuD, associate professor of audiology at Mercy College, Dobbs Ferry, NY, who has worked with cochlear implants since 1979. “It's really exciting to see this technology evolve.” This article reports on today's new products and examines what's on the way. THE IMPLANT CENTERS' PERSPECTIVE In the late 1970s, the earliest cochlear implants were one-electrode, single-channel devices that gave recipients a “very basic perception of sound,” says Jon Shallop, PhD, who works in the Mayo Clinic cochlear implant program in Rochester, MN. Shallop is also a staff consultant and associate professor at the Mayo Clinic and Medical School, which contains one of approximately 300 centers in the U.S. specializing in cochlear implants. “With a single-channel cochlear implant, people could get some idea of loudness, tempo, and time patterns, but not pitch,” Shallop notes. Multichannel cochlear implants came to the U.S. market in the mid-1980s and it's been a fast ride since. By allowing multiple contacts per electrode, multichannels produce a range of frequencies for the cochlear implant user. “This is essential for achieving word recognition,” says Shallop. Technologic improvements have followed in “everything related to cochlear implants,” he adds. “With the first multichannel implants we were excited to see a sentence-recognition score of 30%. Today, that same type of patient is achieving 80% to 90% scores.” “We continue to get iterations of software that is smarter, more adaptable, and, in many cases, faster and more versatile than previous generations,” observes Noel L. Cohen, MD, professor and chair of the Department of Otolaryngology and director of the Cochlear Implantation Program at New York University Medical Center. SURGERY BECOMING SIMPLER AND SAFER While cochlear implants are becoming more complex, the implantation surgery has become simpler. Cohen, one of the nation's most respected cochlear implant surgeons, says, “Audiologists should know that the surgery today is mostly routine. The techniques are readily learned and, unless there is a complication, not terribly challenging.” He adds, “Implant surgery is not dangerous.” Complications remain a possibility, though. According to Cohen, a major problem in the past was a breakdown of the incision and flap, leading to infection. That threat has been greatly reduced by progressively smaller and less invasive incisions. A second complication was incorrect insertion of the electrode or damage to the electrode during surgery. “That was a matter of lack of experience,” says Cohen. Today, that complication rate has also diminished. Cohen continues, “Third is paralysis of the face, a frightening thing, especially to parents of a small child who goes into surgery looking perfectly okay but being deaf, and who comes back with half a face that's paralyzed. It's a horrible condition.” Here again, experience and improved surgical techniques have greatly reduced the incidence of facial paralysis to “something on the order of 0.05%,” says Cohen. (Another serious condition that has been suspected of being related to cochlear implantation in some cases is meningitis. For more on the topic, see the sidebar in this month's cover story.) HOW TO CHOOSE? As manufacturers compete in improving their technology, does one brand stand out as better than the others? “There are no indisputable data to say that one cochlear implant works better than another on any given population,” states Thomas Balkany, MD, another of the leading implant surgeons in the U.S. He is chairman of the Department of Otolaryngology at the University of Miami, where some 80 cochlear implantations are performed annually. “However,” says Balkany, “some design characteristics differ, so we educate patients about all three devices so they can make an informed decision. We insist that they have a good reason for their choice, to ensure there is no misunderstanding.” Esthetic appeal—the size, color, or shape of the BTE unit, for instance—is often a driving factor. So are a device's sound processing strategy, computing power, and battery options. Shallop adds that patients may have a bias toward a particular brand. “I don't mean that in a negative way,” he says. “They may think, ‘Aunt Mary has this particular device and is doing really well with it, so that's what I want to get, too.’” He adds, “We don't try to dissuade someone of their bias. Actually, a pre-set bias could be a positive factor. But we'll show patients demonstration units of all brands, with comparative information about battery life and what they can expect in terms of cost over the next several years.” Most patients will opt for a BTE processor rather than a body-worn model, says Shallop, “as long as the quality of sound is the same. But there are situations where a body processor might be more appropriate,” as with someone who is outside a lot and needs a very durable product. WHAT DO WEARERS HEAR? About a month after implantation, when the surgical incisions have healed, an audiologist “turns on” the implant sound. What exactly does the recipient hear? It's a learning experience, which varies among patients. “Typically, patients have no trouble recognizing speech as speech, but it may sound different from what they remember. Most patients adapt relatively quickly to the new sound,” says Chris van den Honert, PhD, director of research and development at Cochlear Americas. Electrical stimulation produces sound that is “qualitatively different from what the patient is accustomed to from hearing aids,” says Steve Staller, PhD, vice-president for quality, clinical, and regulatory affairs at Cochlear Americas. He explains, “Hearing aids amplify sound and they provide power, but not clarity, to a severe to profoundly deaf ear. Cochlear implants bypass damaged hair cells and stimulate the auditory nerve directly, providing a clearer signal to the brain.” Wearers can detect the subtleties of music, but generally, says van den Honert, “the stimulation strategy has been devised to deliver speech sensation. One thing implants don't do very well is represent harmonic relationships or musical intervals.” But they're working on it. Staller says, “Going forward, a lot of research is focused on clarifying sounds in the diverse set of environments that individuals live in, including music.” BUY NOW OR WAIT FOR NEW TECHNOLOGY? With all the improvements on the way, should a cochlear implant candidate wait for the next generation of technology before proceeding with surgery? That's a question that Douglas Lynch, director of corporate marketing at Advanced Bionics, hears often. As a cochlear implant user himself, Lynch says, “I respond that I was implanted in 1995 with the first generation of technology manufactured by Advanced Bionics. I could have waited, but you have to pick a moment in time and decide, ‘I want to hear better now.' If a cochlear implant is right for you, that's when you get one.” Yet how can Lynch, with his 8-year-old device, hear so well now, including without apparent difficulty during a telephone interview? His answer is external upgrades. “I used to wear a processor on my belt the size of a paperback book,” he says. “It was very, very heavy. But I would have worn a refrigerator on my back to be able to hear. “Now I'm on my fifth generation of external processors. While what's inside is here to stay, I still take advantage of advances in software.” In fact, what's inside can change, too. Lynch says there are times when his internal implant “doesn't have the horsepower to handle new technology.” So, within 5 to 7 years, he will likely get a fully implantable system for his other ear. ADVANCES THROUGH TELEMETRY While on-going research is improving sound quality for implant users, audiologists are benefiting, too. New technology is sharply cutting the time required to program new devices and to detect potential problems. One key to this progress is telemetry, the transmission of data electronically between the implant and the audiologist's computer. Shallop of the Mayo Clinic discusses how telemetry can help: “What if an electrode connection breaks somewhere or comes unhooked and creates an open circuit? How can you get a young child to tell you the electrode is acting intermittently? Well, through telemetry, which all the devices have. We can just hit a button and say, ‘Check electrodes.' If there's an open or short circuit, we'll learn that immediately.” At Cochlear Americas, van den Honert explains that such electronic signals are relayed back through the speech processor to the computer. “This lets you measure electrical discharges from the auditory nerve fibers, using the implant to stimulate and measure the response. It gives you an objective measure of the effectiveness of the stimulus.” This ability is especially important with young children and others who don't give the audiologist reliable feedback. In such cases, for instance, Cochlear's NRT (Neural Response Telemetry) system tells the audiologist if the patient is hearing a particular sound and approximately where that sound falls in the person's auditory dynamic range. Surgeons also use this clinical tool during implantation to check how the auditory nerve is responding to stimulation. Faster programming Telemetry speeds programming, too. Communicating directly with the implant to automatically set measurements on multiple channels simultaneously reduces the need to spend time getting feedback from patients. In addition, the new Advanced Bionics fitting tool, neural response imaging (NRI), evaluates the nerve's response to electrical stimulation. This may speed up programming with very young children. And the company's new SoundWave software sets measures for several channels at the same time, rather than one-by-one. Typically, programming can take about 2 hours, and sometimes longer, says Lynch. We're trying to get that down to an average of 30 minutes or less.” He adds, “Programming can be laborious, and when patients get fatigued, it's difficult to get good responses from them.” Cutting programming time also has financial implications. Lynch explains, “It's important for cochlear implant centers and audiologists [in getting] insurance reimbursement, because typically they can only bill for a session of 90 minutes or less within a 24-hour period.” In other words, if programming takes longer, the patient must return the next day, or the audiologist is not reimbursed for the full session. WHAT'S HAPPENING IN THE MARKET? Following is a summary of the latest developments by the three cochlear implant makers. Advanced Bionics New software is coming this year to program the new Advanced Bionics HiResolution sound processing strategy and to enhance the company's Clarion CII Bionic Ear platform. According to the company, HiResolution brings patients “the fine details of sound for significantly better speech understanding, music appreciation, and overall sound fidelity than is possible with hearing aids.” To do this, it generates greater sound detail—up to 90,000 nerve stimulation pulses per second, using up to 16 independent information channels. “Stimulating the nerves so rapidly kind of keeps them from going to sleep,” says Lynch. “That's closer to how the normal hearing nerve operates.” Also, says Advanced Bionics, sophisticated circuitry extracts fine temporal details of sound, and more numerous filter banks detail spectral information. The system has two styles of externally worn sound processors: the new Auria BTE and the pager-style Platinum Sound Processor. For audiologists, the HiResolution system is said to cut programming time by eliminating measurements that are no longer required. Cochlear Americas The Nucleus 3 system is the latest implant system from Cochlear Americas. The only implant offering a titanium case, it has 22 electrodes and 22 separate channels. The system features the patented Nucleus 24 Contour electrode array. The electrodes are pre-curved for better fit in the cochlea and to minimize pressure on delicate structures during surgery. The implant body has been reduced in size to require less drilling and less surgical time. Last year, Cochlear introduced the ESprit 3G third-generation BTE speech processor for Nucleus 24 recipients. Supporting three speech-coding strategies—SPEAK, CIS, and the ACE family—the 3G is available in many colors and is powered by three zinc-air batteries for 40 to 60 hours or more of operation. This year's “significant enhancements” include the ability to program the 3G processor for Nucleus 22 patients, says Sarah Harms, vice-president of marketing. This includes a “whisper setting” on the 3G, which lets users flip a switch for more gain on softer sounds. There is also a built-in telecoil allowing wireless access to telephones and assistive listening devices. For audiologists, the 3G enhancements include new NRT software to streamline programming. According to Staller, this stimulates nerves more quickly to make faster recordings. Cochlear's SPrint body-worn speech processor, meanwhile, features ADRO (adaptive dynamic range optimization), which continually adjusts sounds to the wearer's dynamic range over 22 channels. Cochlear calls ADRO “smart processing” for knowing when to increase gain for soft speech sounds without boosting background noise. Med-El Med-El introduced the COMBI 40/40+ cochlear implant to the U.S. market in mid-2001 and has seen “tremendous sales growth” here, particularly of its “Baby BTE,” says Chris Bertrand, president and CEO of Med-El Corporation, North America. Bertrand describes the Baby BTE as “something in between” an ear-level processor and one worn on the body. “It's about the size of a pencil, and can be attached to a child's clothing or hair,” he explains. As the child grows, the implant accommodates a variety of wearing options. Alternately, the company's CIS PRO+ body-worn speech processor is about the size of a small portable cassette recorder and fits in a pocket or a carrying pouch on the belt. Two rechargeable or standard AA batteries power the unit for about one full day, and the processor can connect to a telephone, television, and assistive listening devices. The standard electrode design features 24 widely spaced contacts arranged in 12 channels to stimulate more than two-thirds of the cochlea. “We're able to sample sound at 18,180 pulses per second and actually stimulate at the same high rate,” says Bertrand. He adds that the implant a patient receives as a baby is designed to last a lifetime. “But my guess is that as technology improves, patients will want to be implanted with something new every 10 to 15 years.” ON THE HORIZON Meanwhile, all signs point to more dramatic for cochlear implants. will become faster and more and the devices says of the University of his point of as a he would electrodes to continue their so that their implantation less He continues, time you on the cells you may be So we want to make we are doing the possible damage when we do cochlear The implantable device more exciting than the implantable cochlear that such devices could clinical in from 2 to 5 and to market within 5 to The have been and rechargeable batteries that through the progress is being in it implantable will need a power that a says van den battery would with the same of used to power the generation of which have a sound about the size of a half The would be worn a for several have been doing this for Lynch. Advanced Bionics from a that the first implantable and rechargeable he adds, “the has more than the implant hearing U.S. clinical will on a that a hearing and electrical stimulation a cochlear the would into the frequencies electrical stimulation would be used on the sounds. key to improved sound is and says Bertrand. has been to very damage to the cochlea during implantation, and that we can an electrode and the it was the could not simultaneously and electronic sound, Bertrand notes. But research in with a stimulation has Med-El has implanted patients with a short electrode that them to their hearing in the “This will says Bertrand. And he rather than since Med-El is likely to a electrode next year that will a hearing and a cochlear implant to be used in the same ear. He adds, “This will open the cochlear implant market to patients with to severe hearing for the to and electronic sound is a device that does it Cochlear Americas is working on such a on at the University of Here again, an electrode would be part into the cochlea to the good At Staller says show that you the hearing and cochlear implant in one patients hear than with one of devices The device will a BTE hearing with a for cochlear implant adds van den a would down from the BTE into the with a Staller says the device is in clinical now, with possible market in 3 sound quality other enhancements are designed to provide a range and better quality of sound for cochlear implant patients of the strategy is a key says Bertrand. is to a that normal hearing is also how to the of sound, to patients hear better in The is to the hearing aids to and background noise. Cochlear's is “This technology the to on one so you could to one and not signals from or 90 explains van den The user the of a from to a as as in will be what's heard says outside that will be are data to to that two cochlear two hearing a are profoundly it might not be to implant I that it says at the University of Miami, we need more data to show THE The power of cochlear implant is a major in terms of quality and the external speech processor and the internal implant power, with the by frequencies by the battery can be zinc-air and standard AA cochlear implant can a of battery So which is It Jon Shallop of the Mayo explains, is on the If the of the can cut the power needs in it will the life of the power While more rechargeable batteries last longer than But that does not give them a cost the rechargeable batteries have to be Shallop. “It might be to use a standard battery that will say, 5 life is greatly by the hearing says sales for at One rechargeable batteries for hearing and the new One zinc-air battery for cochlear implants. For instance, says, a or a among several people make the device and the battery down By a on the The speech also power says Steve Staller of Cochlear Americas. are more to rechargeable batteries than If an implant is not particularly rechargeable batteries can cost more than This is because they can be only or or so and they're Staller says Cochlear to the average battery cost for its devices to a size also rechargeable batteries for about hours before says Douglas Lynch of Advanced Bionics. one point during the you the battery and in a new It takes about 5 cochlear implant technology in programming and speech has improved speech understanding, as in this of mean over time by The new Auria speech processor from Advanced Bionics is designed to handle the faster speeds of the company's new HiResolution Sound