Inside Look on Candidate Selection for Electric-Acoustic Stimulation Hybrid and Bimodal Cochlear Implantation

AudiologyOnline: Tell us about yourself and your role at Cochlear.

Aaron Parkinson: I am a Principal Clinical Project Manager at Cochlear, where I have worked for more than 20 years now. In that time, I have had the pleasure of being a member of the clinical studies team, a great group of people, personally and professionally, by the way. The title is a little misleading in that I am trained as an audiologist and have a PhD in speech and hearing science.

My major projects have included overseeing the Nucleus® Contour clinical trial, our first perimodiolar electrode array, we affectionately called the “Curly.” I also oversaw early studies that demonstrated the benefits of bilateral cochlear implantation in adults and children (my favorite study, it was rewarding working with children and their parents), and the various trials we have run related to the Hybrid or electric-acoustic hearing. In fact, I have been involved with the latter project for so long, from the very beginning in 1999, that I would venture to say I probably hold some sort of Cochlear record for the longest project and probably explains why I am often referred to as “the Hybrid guy!”

Prior to coming to Cochlear, I worked at the University of Iowa as a research audiologist on the cochlear implant research program for almost seven years. At the time, I also became interested in bimodal hearing, that is using a hearing aid in one ear and a cochlear implant in the other. In fact, it almost became my dissertation project and the early work I did on that came out as a publication soon after I arrived at Cochlear. Basically, as I think about it, my entire cochlear implant career has involved electric-acoustic hearing!

AudiologyOnline: You are a co-author of Candidate Selection for Electric-Acoustic Stimulation Hybrid and Bimodal Cochlear Implantation published in Audiology Practices – what was the goal of this article?

Aaron Parkinson: My co-author and colleague, Dr. Megan Mears, and I share a common belief that our goal as clinicians should be to maximize the benefit to be derived from hearing technology, whatever that technology may be. For today’s cochlear implant candidate that means optimizing not only their cochlear implant but also their hearing aid. In this article, we set out to emphasize the importance of combined use of hearing aid and cochlear implant technology for maximizing outcomes in individuals who are candidates for cochlear implantation. Hearing aids and cochlear implants should not be viewed as competing or conflicting technologies; rather, they should be considered complementary. Dr. Mears and I want clinicians to consider embracing both technologies, whether one considers themselves a hearing aid or a cochlear implant professional. As we say in the article, the potential benefit that patients can receive by effective, combined use of a cochlear implant and hearing aid technology opens up the opportunity for professionals to form rewarding partnerships, with other professionals, that present to the patient as effective and meaningful intervention.

Another point we wanted to make is that cochlear implantation is not a treatment option for those with profound levels of hearing loss only, and, in fact, this has been the case for a long time. Dr. Mears and I aimed to reiterate this fact by pointing out that, with continued advancements in the technology and improved techniques for preserving acoustic hearing, candidates for a cochlear implant will more often than not present to the clinic today with some level of functional low-frequency acoustic hearing. It should not be assumed that those who proceed with cochlear implantation need give up their hearing aids. Rather, they should be assured that they can continue to benefit from both technologies and encouraged to do so.

AudiologyOnline: What are the benefits of combining electric and acoustic hearing?

Aaron Parkinson: Starting with electric hearing via the cochlear implant and what it brings to the table, it is important to understand a little about speech perception and the role that high-frequency information plays in our ability to understand speech. Many people with hearing impairment mainly have a loss of hearing for high-frequency sounds, which are important for understanding speech. High-frequency speech sounds are important for distinguishing consonants, the p’s, the t’s, the f’s, and the s’s among others. It is our ability to distinguish among the various consonants that allows for good speech intelligibility.

Hearing aids can compensate for this loss by selectively amplifying higher frequency sounds. For mild and moderate hearing loss, hearing aids can work well and even for more moderately severe or severe levels of hearing loss hearing aids generally provide improved speech perception. However, once hearing loss progresses to the extent that the high frequencies are severe or poorer, the benefits that hearing aids can provide diminishes. This is where cochlear implants become a realistic option as they are made to effectively bypass the damaged cochlea and stimulate the auditory nerve more directly. Cochlear implants can restore a level of hearing for high-frequency sounds that hearing aids lack for more severe losses, allowing the listener to better distinguish among the consonants of speech.

When it comes to acoustic hearing, being able to continue to have access to lower-frequency acoustic hearing complements the cochlear implant. That is, the acoustic signal via a hearing aid conveys information, such as low-frequency voicing and fundamental frequency cues, that is more challenging, if not impossible, for current cochlear implant technology to provide. Hearing aids alone may not be enough. However, when both the cochlear implant and hearing aid are used together the addition of the low-frequency sounds allows for a number of benefits described in the article. Studies and patient experience have shown improved hearing for speech in both quiet and, in particular, in noise, as opposed to using one or the other device alone.^1,2 The use of a hearing aid also allows the listener to better distinguish speakers, which can be helpful identifying the speaker in a group of individuals or in noise.

Timing cues are better conveyed acoustically, and especially if acoustic hearing is available in both ears, this allows for better localization of sounds as well as for hearing speech in background noise as listeners can better segregate the main talker from the background noise.

Lastly, music perception and appreciation is also better when cochlear implant recipients are able to make use of a hearing aid and having low-frequency acoustic hearing generally improves sound quality and is reported as more natural.

AudiologyOnline: This article was published in 2017 – how is it still clinically relevant today?

Aaron Parkinson: Cochlear this year celebrates 40 years as a company. Despite this very long history and global presence, cochlear implant technology remains underutilized in the face of the highly successful nature of the intervention. Part of the reason may be that many continue to believe that implants are an alternative to hearing aids for those with profound hearing loss only, patients for whom hearing aids provide little to no benefit for speech perception. In reality, cochlear implant indications include individuals with moderate sloping to profound hearing loss, who more than likely will benefit by cochlear implantation and will have some level of functional acoustic hearing after surgery in at least one ear, typically the unimplanted ear. So, for this reason alone, the topic is as clinically relevant today as it was even before 2017. If more patients are to receive cochlear implants, it is also important to understand that these same patients will likely receive the best outcomes from the combined use of a cochlear implant and a hearing aid. If a hearing aid is not an option for the opposite ear, cochlear implantation in both ears may be an option, but that is another topic!

Implant technology has only improved over the years, so there is even less justification for not referring or recommending implantation for those with lesser degrees of hearing loss. Patients don’t need to continue to struggle with hearing aids alone, nor should they. However, it’s important to understand that one doesn’t have to give up on them up either to benefit from a cochlear implant. Quite the opposite, in fact. Those with sufficient residual hearing will likely benefit by both technologies. This has been relatively clear for many years with regards to bimodal hearing, where a patient makes use of a cochlear implant in one ear and a hearing aid in the opposite ear.

More recently, as discussed in the article, the benefit of combined electric and acoustic hearing has been exemplified by the advent of electric-acoustic implant systems such as the Cochlear™ Hybrid™ implant system. A Hybrid cochlear implant is one that provides electric stimulation, just like a traditional cochlear implant, but also effectively has a built-in hearing aid component that allows amplified acoustic sound to be delivered to the same ear. In other words, the Hybrid system combines an implant and a hearing aid in the same ear. Patients typically also make use of a hearing aid in the opposite ear. These electric-acoustic systems continue to generate research interest since their introduction in early 2014 and have reinvigorated interest in the combined use of cochlear implants and hearing aids in general.

Lastly, because Hybrid Systems are designed for people with hearing quite a bit better than traditional cochlear implant candidates, interest in Hybrid has shone a light back on cochlear implantation in general. The Hybrid clinical trial presented another opportunity to illustrate that cochlear implants are not only for those with more profound hearing loss and are not mutually exclusive of patients continuing to use a hearing aid. In fact, it should be recommended that a hearing aid or hearing aids be used in concert with a cochlear implant whether that be a Hybrid, or a more traditional cochlear implant, should there be aidable acoustic hearing present.

AudiologyOnline: What practical guidance can today's clinicians take from this article and implement into their practice?

Aaron Parkinson: Becoming familiar with the indications for cochlear implantation is a good place to start! The outcomes we observe support that cochlear implants should be part of every audiological evaluation in addition to hearing aids. It’s not an either/or decision anymore! I hope a key take away would be that clinicians need to work to establish a network, a care team, if you will, that includes a cochlear implant facility. By working with the cochlear implant team, it seems much more likely a synergy will evolve whereby clinicians will feel comfortable appropriately referring patients for a cochlear implant evaluation.

If the goal is to provide patients with the best possible outcomes from hearing technology, then auditory rehabilitation/habilitation has to include cochlear implants and hearing aids where possible. As I said earlier, they are not mutually exclusive; clinicians should incorporate cochlear implant recipients into their practice, and they should expect to retain their patients! Many will still benefit by a hearing aid combined with their cochlear implant and will still need care related to their hearing aid. So, it is not a given that referral for cochlear implantation is necessarily one way, meaning the loss of a patient to another clinic.

I hope that reading this article generates interest in becoming more familiar with cochlear implants and the benefits they can provide. While articles such as this provide an opportunity for clinicians to better understand the potential cochlear implants have, it is not enough to rely only on literature. I know from prior experience myself that meeting individuals who have been implanted can make all the difference. It is rare to meet someone who describes having received an implant as anything less than life-changing.

AudiologyOnline: What is your favorite part about working for Cochlear?

Aaron Parkinson: My favorite part is to be able to work with the people I am lucky to call my colleagues and, of course, as just about everyone at Cochlear would say, there is pride and reward in doing what we do and knowing that what we do is so impactful. With an audiology background I truly appreciate what our technology brings to the table for people with significant hearing loss. Having seen what the early implant designs could deliver (Cochlear had barely come into being when I was an audiology student) and marveled then, what I see now is nothing short of miraculous.

Read the article now!

To learn more about fitting bimodal patients – watch our course on AudiologyOnline, Optimizing Outcomes with the Smart Hearing Alliance Bimodal Solution: Research and Case Studies

References: 

1. Kelsall D, Lupo J, Biever A. Longitudinal outcomes of cochlear implantation and bimodal hearing in a large group of adults: A multicenter clinical study. Am J Otolaryngol. 2021 Jan-Feb; 42(1):102773. doi: 10.1016/j.amjoto.2020.102773 Epub 2020 Oct 22. PMID: 33161258
2. Ching, T. Y., van Wanrooy, E., & Dillon, H. (2007). Binaural-bimodal fitting or bilateral implantation for managing severe to profound deafness: a review. Trends Amplif, 11(3), 161-192. doi:10.1177/1084713807304357

^{© Cochlear Limited 2021. All rights reserved. Hear now. And always and other trademarks and registered trademarks are the property of Cochlear Limited or Cochlear Bone Anchored Solutions AB. The names of actual companies and products mentioned herein may be the trademarks of their respective owners.}

^{Views expressed are those of the individual. Consult your hearing health provider to determine if you are a candidate for Cochlear technology. Please seek advice from your health professional about treatments for hearing loss. Outcomes may vary, and your health professional will advise you about the factors which could affect your outcome. Always read the instructions for use. Not all products are available in all countries. Please contact your local Cochlear representative for product information.}

^{The Acoustic Component should only be used when behavioral audiometric thresholds can be obtained and the recipient can provide feedback regarding sound quality. The Hybrid L24 Implant is approved in the US for adults ages 18 and older.}

^{The Cochlear Nucleus Hybrid L24 cochlear implant system is intended to provide electric stimulation to the mid- to high-frequency region of the cochlea and acoustic amplification to the low-frequency regions, for patients with residual low-frequency hearing sensitivity. The system is indicated for unilateral use in patients aged 18 years and older who have residual low-frequency hearing sensitivity and severe to profound high-frequency sensorineural hearing loss, and who obtain limited benefit from appropriately fitted bilateral hearing aids.}

^{Cochlear Nucleus cochlear implants are intended for use in individuals 18 years of age or older who have bilateral, pre, peri or postlinguistic sensorineural hearing impairment and obtain limited benefit from appropriate binaural hearing aids. These individuals typically have moderate to profound hearing loss in the low frequencies and profound (≥90 dB HL) hearing loss in the mid to high speech frequencies.}

^{The cochlear implant system is intended for use in children 9 to 24 months of age who have bilateral profound sensorineural deafness and demonstrate limited benefit from appropriate binaural hearing aids. Children two years of age or older may demonstrate severe to profound hearing loss bilaterally.}