Going Hybrid A cochlear implant expert answers member questions about hybrid CIs. Overheard
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Overheard  |   January 01, 2016
Going Hybrid
Author Notes
  • Camille Dunn, PhD, CCC-A, is the director of the Cochlear Implant Center for the Adult and Pediatric Cochlear Implant Programs at the University of Iowa and is a principal investigator on an NIH-funded grant studying hybrid cochlear implants. camille-dunn@uiowa.edu
    Camille Dunn, PhD, CCC-A, is the director of the Cochlear Implant Center for the Adult and Pediatric Cochlear Implant Programs at the University of Iowa and is a principal investigator on an NIH-funded grant studying hybrid cochlear implants. camille-dunn@uiowa.edu×
Article Information
Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Overheard
Overheard   |   January 01, 2016
Going Hybrid
The ASHA Leader, January 2016, Vol. 21, online only. doi:10.1044/leader.OV.21012016.np
The ASHA Leader, January 2016, Vol. 21, online only. doi:10.1044/leader.OV.21012016.np
Bridget Gonzalez: What is the FDA-approved age range for the hybrid cochlear implant?
Camille Dunn: The FDA-approved age for the hybrid CI is 18 years and older.
Dana Spooner: Would anyone under the age of 18 be implanted with a traditional CI?
Dunn: While the device is only FDA-approved for adults 18 years and older, if a surgeon wants to get permission to do an off-label surgical procedure with the Hybrid L24 cochlear implant, they can certainly do that.
Jan Hyono: I have seen a couple of cases where patients were upset that they were not a candidate for a certain technology, so on later hearing exams they would elevate thresholds or perform inconsistently worse on a word-recognition test to try to “prove” they are a candidate. I was wondering, if someone is really not a candidate for a hybrid implant (audiogram doesn’t meet criteria, CNCs [word recognition test scores] are better than 80 percent in both ears, etcetera), how do you recommend counseling them regarding why a hybrid implant may not be the right choice?
Dunn: That is a great question. We have seen this as well. Particularly, it might be in cases where their insurance will cover a cochlear implant but will not cover hearing aids. In these cases, we try to explain that the FDA has only approved the device for specific criteria. We do not know if patients with better hearing or speech-recognition scores will do better with a hybrid cochlear implant over the hearing aids. Additionally, there is also a risk of hearing loss. Furthermore, we would never want to continue with an invasive surgical procedure when the patient could do better or the same with their hearing aids.

“We would never want to continue with an invasive surgical procedure when the patient could do better or the same with their hearing aids.”

Sandie Bass-Ringdahl: Can you tell me what percentage of your patients who received the short electrode implant experienced additional, permanent hearing loss post-implant as well as the percentage who lost hearing completely in the implanted ear?
Dunn: We have implanted nearly 30 patients at the University of Iowa with the Hybrid L24 cochlear implant. Of those implanted, the majority had “good” hearing preservation, meaning had aidable hearing through at least 500 Hz. Additionally, a few patients (~5) had hearing preservation only at 125 and 250 Hz. Finally, about the same number of patients (~5) had total hearing loss. Overall, at Iowa, there was a 79 percent hearing preservation of at least some usable hearing. However, what we have determined is that the amount of hearing preservation does not necessarily predict the speech perception outcome. Some that have lost total hearing have had a 65- to 75-percent improvement on their speech recognition.
Erika Blanchard: When you say the majority had good hearing preservation, is that long term? A few of our patients had aidable hearing for up to three months post-surgery, but then it went away completely by the end of a six-month period.
Dunn: Yes, the majority had hearing preservation long term. In fact, with a different generation hybrid cochlear implant, we have data showing stability of hearing loss for over 13 years in the vast majority of patients. For some reason, there is a critical time period during the first six months following surgery. We have not determined the cause of this, but we are conducting studies with various hypotheses. Nonetheless, most patients keep their hearing and it remains stable. But hearing loss is certainly a risk that the patients need to be heavily counseled on.
Vicki Wauchope: Do you foresee hybrids being approved for kids anytime soon?
Dunn: I do not see it being approved in children any time soon. All of the subjects in the clinical trial that was submitted to the FDA were adults. At Iowa, we did seek an investigational device exemption (IDE) from the FDA to study the use of the hybrid in children 5 to 15 years of age. There are a lot of risks with the hybrid in children, as often their hearing loss is more progressive in nature. I would highly recommend getting multiple audiograms over time to verify progression of hearing loss. We also do this for the adult patients and it would be critical to do this for a pediatric population.
Gonzalez: So do you think the fundamental issue of “risk” will not change for children? [For example], a child could lose all of their hearing in the hybrid ear, and therefore the FDA will not be approving this device (even for teenagers) because the recipient is a minor, thereby not being able to give consent?
Dunn: I think that is an accurate statement.

“There are a lot of risks with the hybrid in children, as often their hearing loss is more progressive in nature.”

Lenea Epstein: Do you recommend that older individuals (65-plus) still seek out whether or not they are candidates, given that you mentioned a possible lesser outcome due to the inability to integrate both signals?
Dunn: I think that it is very important to look at the whole person when determining candidacy for the hybrid cochlear implant. It is important to look at etiology, audiograms, speech recognition, cognitive status and history of hearing loss to determine if your patient is right for a hybrid cochlear implant.
Wauchope: In the case that had the implanted ear progress, did the other ear progress at the same time? Also, what do you think might be the cause of delayed progression of hearing loss when implanted?
Dunn: It is very important to look at the hearing in both ears to determine if the hearing loss is happening in both ears or just the implanted ear. In the case where the patient progressed, it did happen only in the ear with the cochlear implant. We expect that there will be approximately a 20 dB drop in hearing due to the surgical procedure. After activation, for some reason, patients will experience a hearing loss. The nature of this cause is yet to be determined. We are studying many different theories using animal models. Nonetheless, the majority of patients have stable hearing over time. It is also important to remember that the hearing loss does not predict the speech perception outcomes. One of the goals of the hybrid is certainly to preserve the anatomy of the inner ear. However, regardless of hearing preservation, patients do much better with the contribution of the electrical hearing than they did with their hearing aids alone.
Epstein: If candidates are not wearing hearing aids, you recommended a hearing-aid trial. Can you explain the how this can aid in candidacy determination?
Dunn: Yes, we recommend a hearing-aid trial. The reason is to obtain an accurate picture of their benefit with hearing aids before proceeding with a cochlear implant. We would never want to implant someone who could benefit with a hearing aid the same or better.
Rachel Muller: What is the currently known percentage risk of losing acoustic hearing in the lower frequencies with implantation of the hybrid?
Dunn: Based on the data from Iowa, we currently have a hearing preservation rate of 79 percent. This includes those with good hearing preservation and those with some hearing preservation, as discussed earlier. I don’t mean to harp on this, but I think the biggest thing that we have learned is to look at the whole person with determining candidacy. It really does go beyond the audiogram and the speech perception scores. These things are key. If you have a candidate that you think might be a good for a hybrid, but aren’t sure, I recommend talking to your clinical representative through Cochlear. They can be instrumental in helping you decide if they are a good candidate. Also, following implantation and activation, have your Cochlear representative come for the first programming session. They can help you program the acoustic component and the electrical hearing. Additionally, Cochlear has a worksheet that can help you walk through what the appropriate technology might be for your patient.
Gabe Bargen: If all residual hearing is lost after being implanted with a hybrid CI, is it possible to be re-implanted with a more typical array of electrodes?
Dunn: It certainly is possible to re-implant, but we would not recommend that, mostly because it is not necessary. The Hybrid L24 can be reprogrammed so that the frequency allocation covers the full frequency range. For our patients who have lost all hearing, most do very well with the Hybrid L24 device. If you want to consider explantation/re-implantation, I would not do it right away. I would wait and see how they do with the Hybrid L24 first to see their outcomes. If they are not progressing as expected, again, I would contact your Cochlear representative and verify that you are programming things correctly and have them guide you through the next step.
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January 2016
Volume 21, Issue 1