Laurie S. Eisenberg, PhD, is a scientist and the co-department head of the House Ear Institute (HEI) Care Center. She was among the individuals in the original group of cochlear implant co-investigators at the House Ear Institute during the late-70s, and was on the first pediatric CI team in 1980. Eisenberg’s current research includes a major 2003 NIH grant for a 5-year investigation using longitudinal and cross-sectional studies to measure and track auditory-perceptual development and the emergence of spoken language in hearing-impaired children between the ages of 6 months to 5 years.

Laurie S. Eisenberg, PhD

HR: You were among the co-investigators with Dr. William House 25 years ago when he performed the first pediatric cochlear implant procedure. Can you provide a little overview of your experiences during the early days of the HEI implant program?
Eisenberg: I was a young audiologist just out of my master’s program at California State University, Northridge in 1976 when I first went to work for the House Ear Institute (HEI) in Los Angeles. Norma Norton, an audiologist and speech-language pathologist at HEI, hired me to carry out aural rehabilitation with the first adults who received cochlear implants. The implant program was then called the Hearing Research and Rehabilitation Center (HRRC) and the original name of the implant center was the Walt Disney Hearing Rehabilitation Research Center. Walt Disney’s name was added after Disney’s widow provided a large donation that paved the way for those early research efforts.

At that time, we treated only post-lingually deafened adults, and didn’t really know how to determine cochlear implant candidacy. As a result, we required that the patients undergo a minimum of 6 months rehabilitation with powerful body hearing aids. The patients who made no progress with hearing aids were referred for a single-channel cochlear implant, which had been developed at HEI by Dr. William House.

An interesting outcome of this training was that a number of patients who’d been identified as potential cochlear implant candidates actually derived benefit from hearing aids. This was a remarkable finding in view of the fact that many of them had been told by their physicians that nothing could be done to treat their hearing loss and that they should take classes in lipreading or sign language. In those days, audiologists were not permitted to dispense hearing aids.

Because those patients were not able to be assessed on standard audiological speech recognition tests, we had to develop new tests to determine cochlear implant efficacy. Two tests that were developed in those early days were the HRRC Rhyme Test and Environmental Sounds Test, and several years later, the Minimal Auditory Capabilities (MAC) Battery, which was developed by investigators at UCSF and became the standard for the field in the late 1970s and 1980s.

Because of our success at HEI with the single-channel implant in adults, the decision was made in 1980 to implant the first child, and the Children’s Program (Center for Deaf Children) was born at HEI. [HEI implanted five older children ages 8-17 years in 1980 before implanting the first pre-school-aged (3 years old) child in 1981.]

Soon, other centers around the country began collaborating with us in the FDA clinical trials, sponsored by the 3M Company. A few of the team members on the original HEI pediatric cochlear implant project are leaders in the field today. They include Karen Iler Kirk (now working with Richard Miyamoto, another former co-investigator at Indiana University), Lisa Tonokawa (now at the California Ear Institute), and Carolyn Hill Brown (now at the University of North Carolina).

A lot of neurotologists and audiologists—too many to name—got their start as co-investigators in these first clinical trials with cochlear implants.

HR: How did that early work in the HEI program shape your future research?
Eisenberg: I was on the staff at HEI for 10 years, when I decided to return to school to earn a PhD. In 1986, I entered the City University of New York (CUNY) Graduate School, studying with Harry Levitt and Arthur Boothroyd. The primary reason I wanted to attend CUNY was because most of the research articles I had been reading during that time were coming from students in that program; it was a program that emphasized sensory aids for individuals with hearing loss. My dissertation focused on hearing aid selection for children. After graduating, I went to UCLA for a 2-year post-doctorate position to study speech perception with Don Dirks. At UCLA, I obtained my first NIH grant, a clinical investigator development award, and continued to pursue research in subjective judgements for hearing aid selection for children.

After 6 years at UCLA, I received a call from House Ear Institute asking if I’d be interested in becoming a scientist in their Children’s Auditory Research and Evaluation (CARE) Center. I returned to HEI in 1996, and have been here ever since. So I’ve had two major careers at HEI: one as a clinician and now as a scientist. My early clinical experiences at HEI were a powerful launching pad for the rest of my research career, and I’m sure many other current research scientists who were involved in the cochlear implant program feel the same way.

HR: What was your experience with the controversies surrounding the first pediatric CI?
Eisenberg: My first experience with the controversy was when Norma Norton interviewed me for the HEI position. She said, “I have to warn you that this is such a controversial area that it could ruin your career as an audiologist.” When you’re young, you don’t really think about such potential outcomes.

I like to think of the controversies during that time as really being opposing philosophies between the scientific and clinical communities. On the one hand, you had the scientists saying that it wasn’t right to implant humans because there were too many unknowns about device safety. They advocated preliminary research with animals. The clinicians—primarily neurotologists on the West Coast, including Dr. William House at HEI, F. Blair Simmons at Stanford, and Robin Michelson and Robert Schindler at UCSF—believed that there were a lot of people who could be helped by this technology and clinicians could better determine benefit with human clinical trials. In fact, the idea for cochlear implants first came from two surgeons (Dijourno & Eyries, 1957), who experimented with electrical stimulation of the auditory system in a patient in France.

Another opposing philosophy was the context in which the implant was evaluated. Scientists evaluated the implant in the context of normal hearing. In other words, if hearing was not restored to normal, then implant surgery was not worth the potential risks. Conversely, the clinician evaluated the implant in the context of deafness. That is, they had the attitude that providing some sensory awareness for a patient would be better than total deafness.

In the early days, cochlear implants were very controversial within the Deaf Community, and still are to a certain extent. Fortunately, the cochlear implant has been very successful and most of the controversies have been laid to rest. There are still a number of scientists who continue to conduct basic research on animals to address questions of safety, effects of chronic electrical stimulation, benefits of early implantation, etc. However, many clinicians have devoted their careers to cochlear implants, and it has become accepted clinical practice.

HR: Where are those early implanted children 25 years later?
Eisenberg: That’s a good question. I suspect that the majority of them are non-implant-users; however, as the CI technology advanced over the years, some patients were re-implanted with multi-channel systems, and they continue to use those devices.

The children and their parents who entered the first clinical trials are truly the heroes of the story, and they are the real pioneers who made all subsequent future development possible. In those early days, we purposely selected children for whom nothing else had worked. They were not the best candidates and, if you read our first publications, you will note that the average age of implantation was about 8 years and the majority of the children communicated by sign language.

From all of the studies conducted over the past 25 years, we know that older children who have not incorporated sound into their daily living experience and do not communicate orally are far less likely to be successful with an implant. Thus, the majority of the first group of children who received cochlear implants would probably not be considered ideal candidates by today’s standards.

HR: What is happening in terms of research on critical age of implantation and device efficacy?
Eisenberg: Through clinical experience, we’ve known for many years that “younger is better.” The auditory-verbal therapists have always advocated putting hearing aids on babies—even before we had newborn hearing screening techniques – to ensure early auditory stimulation. Over time, research has come out supporting this fact. A landmark study conducted by Yoshinaga-Itano and her colleagues showed that those babies identified with hearing loss prior to the age of 6 months demonstrated significantly higher language abilities relative to those children identified after the age of 6 months.

Even in the early years of cochlear implants in children, clinicians have recognized the importance of early implantation and, as a result, children as young as 2 years were able to be implanted under FDA regulations. In more recent years, this age boundary has been lowered to 1 year for children with profound hearing loss. Research studies also are verifying that the younger a child is implanted, the better their communication outcomes.

HR: What do you think are the biggest developments in cochlear implant technology? How effective can the devices become?
Eisenberg: In my view, one of the most interesting aspects about cochlear implants is that performance continues to improve with advances in technology. There has not been one specific innovation that has resulted in a monumental improvement—progress has been very gradual. We are still waiting to see how far the technology will take us. Will we ever be able to restore hearing to normal? I can’t answer that question, but I do know that performance in many cases is remarkable.

For me, over the past 29 years, the “aha” moment came when patients progressed from closed-set speech identification to open-set speech recognition. It also is impressive that new large scale studies conducted on children with implants are now implementing control groups of normal-hearing peers, as in the multi-center study titled “Childhood Development after Cochlear Implantation” [principal investigator: John Niparko, MD, Johns Hopkins University].

I also believe that the field has progressed so rapidly because individuals from many different disciplines have collaborated on the development of this technology, including professionals from the fields of medicine, engineering, physiology, biology, psychology, audiology, speech-language pathology, and education.

HR: What are your inclinations in recommending implants on auditory neuropathy/dyssynchrony patients?
Eisenberg: There have almost certainly been a number of patients with auditory neuropathy who have been implanted over the past 25-30 years. Before we had otoacoustic emissions (OAE) measures, we couldn’t differentiate sensory loss from neural loss. In patients with auditory neuropathy, the outer hair cells typically are intact (as evident by present OAEs) but the auditory brainstem response (ABR) is absent. The absence of ABRs is usually an indication for implant surgery.

Today, patients are being implanted with clear diagnoses of auditory neuropathy. At our center, we treat neuropathy children the same as we do with all other children undergoing pre-implant evaluation. We require that they have severe to profound hearing loss on an audiogram. The best surgical ear is selected and, if both ears are equal from a surgical standpoint, then the best functional ear is chosen.

HR: The FDA has approved binaural implants for trials. What is your experience and outlook on them?
Eisenberg: HEI has always been one of the more conservative centers in terms of candidacy, so we have been one of the last centers to become involved in bilateral implantation.

We now have 10 children with bilateral implants. It’s difficult to quantify improvements, probably because our current tests are not sensitive enough. I know that special assessment tools are being developed and we look forward to implementing them in the near future when they are made available to us. It has been our belief that the earlier a child is implanted bilaterally, the greater the potential for success.

I might add that we have experience with children who are able to use a hearing aid on one ear and an implant on the other. At present, we are collaborating on a study with researchers from Indiana University (Drs. Karen Iler Kirk and Rachael Holt) on this area of investigation. The results from that study will shortly be published in Ear & Hearing. To briefly summarize the results, we found that children with substantial residual hearing in one ear (hearing aid side), who use a cochlear implant on the other side, perform best in binaural listening conditions on measures of speech recognition—particularly on those measures in noise.

HR: Where do you see the greatest room for improvement and development in cochlear implant technology?
Eisenberg: In the short term, the “holy grail” of implant development seems to be improved music perception. This advance will require much better spectral resolution than the present devices provide [see HR News on p 80].

I also think that there are some other very interesting areas of investigation that are presently ongoing. One area is in electro-acoustic hearing, where a hearing aid is coupled with an implant for those patients with steeply sloping hearing loss. This work has been pioneered at the University of Iowa by Drs. Bruce Gantz and Chris Turner.

Another interesting area of research is with the auditory brainstem implant (ABI), which was first developed at House Ear Institute by Drs. William House and William Hitselberger for patients with NF2. Current research led by Dr. Vittorio Colletti in Italy and Dr. Bob Shannon at HEI is showing amazing results in non-NF2 patients undergoing auditory brainstem implantation. Also very interesting is the research being carried out at Kresge Research Institute in Ann Arbor, Mich, on a drug delivery implant system to preserve residual neural elements.

HR: Since you mentioned it, if the future might entail at least the possibility of regrowing hair cells (say, in 20 years), what do you tell people and how do you advise them on CI decisions? Is it possible that we’re destroying elements in the cochlea that could be useful as future technology progresses?
Eisenberg: I would strongly advise against waiting to see what scientific research in the area of hair cell regeneration will deliver, simply because it may be a long time before we arrive at clinical application.

If you are a parent of a child with severe to profound hearing loss and want your child to develop spoken language, it is crucial to seek treatment sooner than later. In addition, by waiting, the ear may undergo further deterioration and auditory deprivation. So, by seeking an implant now, you may actually negate the effects of auditory deprivation and promote maturation of higher auditory centers.

I would not want to deprive a child of hearing in hopes that hair cell regeneration—in whatever form it may take—will be available at some future point.

HR: Considering all the new types of technology being developed—from semi-implantable hearing aids, middle-ear implants, BAHA, etc, as well as hair cell regeneration—do you think cochlear implants will assume a greater or lesser importance in the future?
Eisenberg: I believe that cochlear implants will have even greater importance in the future, especially if cochlear implant technology continues to undergo new development and we can extend this technology to a greater number of individuals who may not have been considered typical implant candidates before.

Karl Strom is editor of The Hearing Review. Correspondence can be addressed to him at kstrom@ascendmedia.com.   Laurie S. Eisenberg, PhD, can be contacted at: leisenberg@hei.org.