The Future of Cochlear Implants: Experts Discuss Totally Implantable Cochlear Implant (TICI) Feasibility Study Results

A major milestone in the treatment of hearing loss was reached with the publication of a feasibility study on the Totally Implantable Cochlear Implant (TICI) earlier this year. We sat down for an in-depth interview with the leading investigators of the study, Prof. Philippe Lefèbvre, MD, PhD, Head of the ENT Department at the Centre Hospitalier Universitaire of Liège in Belgium, and Prof. Joachim Müller, MD, PhD, Head of Otology and Cochlear Implants in the Department of Otorhinolaryngology, Head & Neck Surgery at Munich University LMU.

Our interview explores:

Semi-Implantable vs. Totally Implantable Cochlear Implants

MED-EL: It’s an honor to have you both here today. In general, what advantages do totally implantable devices have over conventional devices for patients?

Philippe Lefèbvre (PL): The major advantage for patients is that there’s nothing outside. You can use it very freely in any condition like swimming, taking a shower, doing sports, wearing a helmet while you’re motorcycling, skiing, etc. It’s very, convenient, so you can almost forget that you have a device, and that’s probably one of the most important things.

Joachim Müller (JM): Fully implantable devices give the patient the ability to hear in all situations of life. What we learn from the patients with fully implantable devices is they feel more normal, and these devices can cover specific situations where external devices are somehow limited.

This makes a difference in choosing and developing in their professions. This is a dream that we have had since the seventies, and that’s a dream for many with hearing loss: to get closer to “normal.” And, with respect to European handicap laws, we are even closer to a normal hearing situation with this device.

PL: I would just add something: While it’s important for professional situations, another situation is even more important, and that’s family. Let’s say you have young children crying at night, and you need to wake up. If you have a totally implantable device which is turned on, then you will wake up and get up to check on the child. So, in terms of family life, it changes a lot of things.

JM: That’s right, and it’s also a change for us as professionals. What we learned from patients about being able to hear for all 24 hours with the TICI has changed our view of hearing situations that were once assessed as maybe not being so important. We used to be happy that we could even restore a part of hearing and were able to give open-set speech understanding with a semi-implantable cochlear implant.

There are situations related to quality of life that are difficult to measure. We get the impression that patients who have received the modern TICI report and experience personal improvements in quality of life that we don’t yet know how to measure—that’s a new dimension that we are now going to explore scientifically.

PL: I would never have imagined that before a patient said, “Wow, it is great because, when I’m swimming, I can also socialize!” Clearly there’s an advantage.

MED-EL: So, it seems clear that parents with babies as well as people with specific professions where they might be on call at night, such as firefighters or medical professionals, could really benefit from the TICI. Are there other specific types of people who could gain concrete benefits from having a TICI instead of a conventional semi-implantable cochlear implant, which is known simply as a cochlear implant today?

PL: I think there’s no exception. Any cochlear implant recipient, anyone who qualifies for a CI can benefit from it. It’s not only for specific professions—it’s anyone, especially given the fact that the results are completely similar to using an external processor.

JM: I agree. In principle, every cochlear implant candidate can benefit from a fully implantable device. However, we’re at the beginning of this new era, and we have about five years of experience with the device so far, so I would be careful about implanting everybody who is a candidate with a TICI.

It’s a bit early to say, but it will be worked out with more experience in the future. But the conclusion so far is, for us, it’s surprisingly good, and it has exceeded our expectations by far.

PL: I fully agree. For someone who completely qualifies for cochlear implants, no matter what profession, they can benefit from it if they want it and need to hear better. It is best, as you said, to start with the normal classical indications and, from that, we will discover more and extend the indications eventually.

MED-EL: If we think further into the future when we have future generations of TICIs, do you think totally implantable cochlear implants might someday completely replace all standard cochlear implants with external processors, or will both coexist as options for treating severe-to-profound sensorineural hearing loss?

PL: It’s always difficult to predict the future, but I think that the answer is probably yes—with a few exceptions. In some conditions, you will need to keep the semi-implantable generation.

JM: We cannot foresee the future. It’s always nice to speculate what we can have, but I’m pretty happy with what I have now. Looking around the world, at other countries, other social situations, and the ability of surgeons around the world, there will still be a place for semi-implantable cochlear implants. We have not solved the reimbursement question, but we don’t know what the future will bring.

TICI Surgery & Fitting

MED-EL: Moving on to surgery, how does TICI implantation differ from standard cochlear implantation at this time?

PL: Only microphone placement. And a little more, but it’s not such a big issue for an experienced surgeon in CI. There are a few things you really need to take into account, but basically, it is not a very difficult surgery compared to regular CI surgery.

JM: As Philippe said, the microphone needs a little bit more attention, and the implant is a little bit bigger, so the surgery will take longer, as far as we have seen in the study. In the end, it’s all about precision to add the additional steps in the right order. It needs a little bit more concentration from the surgeon.

We should be aware of that since the patient should wear the device for a long period or the rest of their life. And that’s what we have to keep in mind when we do the surgery.

PL: I completely agree. If you want to have good results, the placement of the microphone is an important step. Removing the muscles above the membrane is also key, and if you do not proceed properly with these steps, then the results will not be as good. But for experienced surgeons, it’s not a major issue.

MED-EL: The MED-EL CIs currently on the market allow you to provide your patients benefits from covering the entire cochlea and preserving structures in the inner ear. Is this all still possible with a TICI?

JM: With the feasibility study, I’m very happy that I was able to use the FLEXSOFT electrode with a TICI so we could pay attention to these important aspects.

What we see with the patients at the one-year test interval is there’s no difference between the invisible mode and the mode with the behind-the-ear processor. It’s surprising. It’s completely different from what we know from the literature and what we know from the reports from other fully implantable devices. This is a big difference, and this difference is the technology and the engineering made by MED-EL.

The TICI only makes sense if we have no differences in speech understanding between the behind-the-ear processor and the invisible mode. At a conference 15 years ago, I was at breakfast with one of the prototype users of a TICI from a competitor, but he wasn’t using it because the decrease in speech understanding with the invisible mode was so big that he could not understand much.

PL: I just want to add that the same electrode arrays and same technologies are behind it, but there’s even more now. You can also now do electrode insertion and placement in a motorized or robotic way, with a 0.1 mm per second insertion as we now do on a regular basis for normal CIs.

There is not a degraded signal or some kind of lower results. Here we have the same type of result. For me, that was the most striking thing we could see. And even more, when you have hearing in noise, the data are the same, and that was not expected.

MED-EL: Were you referring specifically to OTODRIVE for electrode insertion speeds at 0.1 mm per second that you have used with your patients after completing the feasibility study?

PL: Yes, you take OTODRIVE at the time of insertion, and you just open your round window membrane and boom. Go for it. No problem. It adds a little more time as Joachim said.

MED-EL: Was it possible to perform anatomy-based fitting with these patients with TICIs?

JM: All of these patients underwent a CT scan after surgery, and all these patients underwent anatomy-based fitting automatically because that’s standard in our clinic.

PL: Yeah, for me, anatomy-based fitting is also the standard procedure. Sometimes we do it manually because we couldn’t get the images after surgery or for some different reason. But this is very rare. Here we did anatomy-based fitting, so the procedures run as normally as they do for a cochlear implant.

MED-EL: How long does TICI surgery take, and how would this compare to the typical procedure with a conventional cochlear implant?

JM: In our hands, it was roughly 1.5 or double the time of a semi-implantable cochlear implant.

This may be caused by the study conditions since we have to train the operating room people. We added some more microphone testing, but in general, I think that’s a rough estimation for us.

PL: I agree. Looking at surgical time itself, I would say about two hours. It’s a little more time than a semi-implantable CI in my hands. It’s about 20 minutes more for management of the microphone. And then some time that was needed to perform the various things: flattening the skull, making the groove, screwing the microphone in, and things like that. Anything that’s new takes more time.

JM: What we saw in the feasibility study and the registration study was that we had quite a steep learning curve, so time decreased. Once we do it more often and with a shorter interval between two surgeries, everything goes more smoothly.

Follow-Up With TICI Recipients

MED-EL: How long ago were the patients in the feasibility study implanted with a TICI, and how are your patients doing now?

PL: Exactly five years. Now is the fifth anniversary. The patients are still happy with it and still use it and are just behaving like normal CI patients. Sometimes they come back with a little complaint that has nothing to do with the implant itself, but it’s still working absolutely normally. It’s truly comparable to a “regular” CI which is a semi-implantable CI—I would now call them semi-implantable and totally implantable cochlear implants.

JM: Yeah, it’s the same with the Munich patients as well. All of the implants work completely perfectly. No technical issues, and all patients are happy over the five years. They have a variety of smaller complaints related to the underlying disease. In the end, it’s working uneventfully perfect for all the patients.

MED-EL: Would you like to share a story about working with your TICI patients?

PL: The first patient that I implanted was 22 years old from a family where they have genetic hearing loss. He said he wanted to be helped, on the one hand, but on the other hand, he couldn’t stand for aesthetic reasons to show that he has a problem and wear an external processor. When I said he can receive a TICI, he said, “Yes, I want it!” So he was the first who got it, and we had a little trouble with him once we said we need to do a comparison with the external processor because he didn’t want to wear the external processor. He was so happy with the TICI. He used it immediately, and he didn’t want to use the external processor. It was very important for him not to show off or stand out.

JM: I think the most impressive situation was a young lady who has a semi-implantable CI and a TICI, and she described the advantages of hearing while she’s going swimming with friends, and she’s not excluded. She can talk in all situations, she can hear overnight, and she described the sound quality and the speech quality as well as the learning aspects as similar or even comparable to a semi-implantable CI. At the one-year interval, performance was all about the same, and when I saw her for the four- and five-year intervals, she preferred the TICI over the other CI. She enjoyed when she’s at the hairdresser that she can discuss details of the cut without putting on external components, and in the morning when she showers, she enjoys listening to music. The patients all had similar stories.

Totally Implantable Cochlear Implant Feasibility Study Results

MED-EL: In terms of speech perception and hearing outcomes, how does the TICI compare with semi-implantable CI users? Were there any remarkable differences?

PL: There were no differences.

JM: As we have seen in the feasibility study, at the one-year interval, we have no differences in speech understanding, and for the three Munich patients, we had a German speech test with 72% monosyllabic words with the variability that we know from all cochlear implant users. In terms of signal-to-noise ratio in speech understanding in noise, you have -2.2 dB, which is quite an outstanding result, and this remained stable for all three patients over five years.

MED-EL: When we think specifically about the measures related to quality of life, how do the pre-op results compare to the post-op results?

JM: Quality of life is difficult to measure. If we discuss quality of life, everybody feels he’s an expert.

So when it comes to quality of life, for me, it’s still open how we define this. We have questionnaires for hearing-related quality of life. All the patients have an improvement in hearing compared to pre-op, so this increases their quality of life, and, with TICI, they have an additional increase because they can hear 24 hours a day.

The stories we shared earlier from recipients show this aspect of quality of life that these patients experience, and it’s the real benefit. As we said in the beginning, we are exploring a new dimension of quality of hearing, and I’m not sure if we have the proper measurement to assess this.

PL: To me, one thing is the most important. That’s showing that a patient actually prefers the quality of life or the quality of the sound. When we analyze the datalogging, this shows the usage of the invisible mode is 90% of the time and the use of an external processor was less than 10% of the time. And that’s the most important thing to me.

MED-EL: Was there anything else that surprised or shocked you as you took part in this groundbreaking project?

PL: The quality of the signal-to-noise ratio was not expected with one microphone placed under the skin. Clearly this was wow! It is exactly comparable to the external processor that has two microphones on it. Here, we have one under the skin, and we get the same result! That was kind of a shock.

JM: I’m surprised by the performance and the patients’ satisfaction. I was excited by a number of new research questions that came up when speaking to the patients. The outcome over five years was a good surprise

The big surprise was the superiority in outcomes and technology compared to what we knew from the literature and from other attempts to develop an invisible or fully implantable device.

The Totally Implantable Cochlear Implant: A New Era of CI Technology

MED-EL: What was it like to reach this major milestone with MED-EL?

JM: It was a pleasure to continue the long cooperation and partnership we have had with all the MED-EL devices. This device was the highlight, and I’m grateful that MED-EL was interested in our experience.

PL: I completely agree. It was a great adventure, and I was extremely honored to be a part of your team with the first people in the world to try this and start this new adventure. Especially when the data were out, it was so nice. It was a genuine pleasure.

JM: It’s outstanding to see how MED-EL approaches a problem, how they structure it, how they analyzed it in such detail, and I think this is still the spirit of MED-EL’s beginnings—a spin off from a university project from academics who are interested in academically analyzing a situation and coming to solutions. Thank you to MED-EL for realizing this project. The technical solutions and the realization of this project are much more complex than the surgical aspects that we have contributed.

PL: It was a real pleasure to be there and see that MED-EL has developed something that they gave us to try that really achieved everything in every criterion that we would have dreamed of.

I remember when we had a meeting when they showed us and asked for our ideas. Each time I had a question, the answer was already on the next PowerPoint slide, and that was really great! At the meeting, the idea was developed to use the FLEXSOFT electrode in addition to the FLEX28, but I remember that everything else was sorted out before, and that shows the great achievements of MED-EL.

MED-EL: Professor Müller and Professor Lefèbvre, we would like to thank you for your time and contributions to this interview, to the feasibility study, and for your expertise along the way to reaching this amazing milestone that marks the start of a new era in cochlear implant technology.

While the feasibility study has provided promising results to move forward with further research, TICI remains under research and is not available for commercial use at this time.

Views expressed in this article are those of our guests. Both authors of the feasibility study are first authors, listed in alphabetical order.