Cochlear Implants
by Jessica Ballard, AuD

A Deeper Dive into Nucleus® SmartNav Intraoperative Testing

October 21, 2024
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  • Approximately 5 minutes to read
  • Learning objectives:
    • Understanding Placement Check in the SmartNav System
    • Interpreting impedance measurements
    • Utilizing Neural Response Telemetry

Intraoperative testing using tools such as Nucleus® SmartNav may provide surgeons and audiologists valuable real-time insights regarding the surgery, device function, and neural response to stimulation. The operating room (OR) is also a unique environment that requires quick decision-making and interpretation of the information available to the surgical team. This article will help provide surgeons and audiologists a better understanding of Placement Check, Impedance telemetry and Neural Response Telemetry (NRT) in the OR and interpretation of those results.

What is Placement Check?

The Placement Check algorithm is an extremely valuable new tool which helps surgeons confirm proper placement of the electrode array. To do this, Placement Check analyzes trans-impedance patterns between electrodes across the electrode array. This is performed by delivering stimulation through each electrode and recording the subsequent current level on all other intracochlear electrodes. The algorithm expects specific patterns of current flow in a normal cochlea. To ensure any potential issue with placement is identified, Placement Check is designed to be very sensitive and will automatically detect anomalies where there is a high probability of a fold or even subtle variations in expected current patterns. When a potential issue is identified, SmartNav’s Placement Check indicates the range of electrodes likely effected. In these situations, imaging may be considered to further confirm placement of the array, especially in cases of abnormal anatomy where current flow within the cochlea may also be atypical. 

What do Impedances tell us?

The purpose of the impedance measurement is to ascertain the electrical status of individual electrodes. The impedance of an electrode not only reflects the electrical status of the electrode but also the resistance to the flow of electrical current through surrounding tissues (i.e. fluid, fibrous tissue, bone). Normal impedances will be reflected as ‘green’ in SmartNav and will have impedance values less than 30 kOhms. Normal impedance findings confirm normal electrical function of implant electrodes. 

How to interpret Impedance anomalies in the OR

Incidence of electrode anomalies is rare, occurring in only 0.7% of electrodes.1 In addition to this, Goehring et al reported 82% of electrodes with abnormal intraoperative impedance resolved by the postoperative interval.² However, understanding the difference between open circuits and short circuits and potential for resolution is important in the OR. 

  • Open Circuits are defined as where the continuity has been broken by an interruption in the path for electrons to flow. Gushers, abnormal anatomy, or air bubbles are thought to contribute to prevalence of open circuits, making them more common intraoperatively and also more likely to resolve by postoperative fitting. 2,3
    • A short circuit is when there is little or no resistance to the flow of electrons between two electrodes and occurs rarely in only 8% of cases where electrode anomalies are observed intraoperatively. 2,3 
    • Multiple electrode anomalies or a high ECE2 (MP2) may also affect SmartNav’s ability to obtain Placement Check. In some cases, this may be resolved through reconditioning the electrode by repeating the Impedance and Placement Check measures.

Abnormal impedance findings should be evaluated case-by-case with consideration to type of electrode anomaly (open vs short), number of electrodes affected, anatomy, potential air bubbles, or other potential contributing intraoperative factors. For support with intraoperative questions, contact our Surgical On-Call team at (877) 279-5411. 

What information does Neural Response Telemetry (NRT) provide?

SmartNav has the ability to perform AutoNRT and/or Advanced NRT. The NRT measurement records the synchronous neural response, also referred to as the Evoked Compound Action Potential (ECAP) occurring in response to electrical stimulation in the cochlea. NRT is present in approximately 96% of patients, and in conjunction with other measures, can provide added confidence for postoperative counseling and activation.4  

What if my patient does not have NRT responses? 

NRT is a peripheral neural response and is not considered a test of hearing. Neural Response Telemetry recording parameters are also more limited compared to those which can be utilized when programming. Some patients may require different parameters in their MAP to hear with their cochlear implant.  In addition to this, Absent NRT responses are not an indication of device malfunction. If NRT is unexpectedly absent, impedances and Placement Check should be confirmed, and imaging may be considered to further evaluate placement of the electrode array. 

The intraoperative measurements discussed including Placement Check, Impedances and Neural Response Telemetry provide valuable information during surgery.  Although tools such as SmartNav are designed with an intuitive workflow, interpretation may be required if atypical findings present. Understanding the differences between these measures, potential results, and implications will optimize the surgical experience and deliver added assurance that surgery was successful. For more information about SmartNav, please reach out to your local Cochlear Representative or visit this website: https://www.cochlear.com/us/en/professionals/connected-care/surgical-care

1. Mehta N, Chu P, Birman C.S. To Use the Back-up Cochlear Implant or Not?  Using Intraoperative Impedance to Guide Your Decisions.  Otol Neurotol. 2022; 43:e408-e413. 

2. Goehring JL, Hughes ML, Baudhuin JL, Lusk RP. How well do cochlear implant intraoperative impedance measures predict postoperative electrode function? Otol Neurotol. 2013; 34:239–44.

3. Kuphaldt, T.R. (2006). Lessons in Electric Circuits, Volume I – DC. Fifth Edition. Retrieved from: http://www-mdp.eng.cam.ac.uk/web/library/enginfo/textbooks_dvd_only/lessons_pdf/DC.pdf

4. Cafarelli Dees D, Dillier N, Lai WK, von Wallenberg E, van Dijk B, Akdas F, Aksit M, Batman C, Beynon A, Burdo S, Chanal JM, Collet L, Conway M, Coudert C, Craddock L, Cullington H, Deggouj N, Fraysse B, Grabel S, Kiefer J, Kiss JG, Lenarz T, Mair A, Maune S, Müller-Deile J, Piron JP, Razza S, Tasche C, Thai-Van H, Toth F, Truy E, Uziel A, Smoorenburg GF. Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system. Audiol Neurootol. 2005 Mar-Apr;10(2):105-16. doi: 10.1159/000083366. Epub 2005 Jan 12. PMID: 15650302.

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Sarah Hughes

Preventing listening fatigue this holiday season with tips from Dr. Sarah Hughes

December 20, 2021

By Sarah E. Hughes B.Sc., M.H.Sc.,Ph.D., Research Fellow, Centre for Patient Reported Outcome Research, University of Birmingham, United Kingdom

Sarah Hughes

Here are some tips to making sure your patients can be a part of the conversations and moments that they care about the most:

Tips from an expert to manage listening effort during the holidays

As cochlear implant recipients, your patients may find that they are extremely tired by the end of the day. Interestingly, recipients often fail to connect their fatigue with listening and the increased effort needed to ensure listening success.

Listening effort is a term used to describe the exertion of brain power used to pay attention and understand spoken language.

It’s important for recipients to appreciate that listening effort is a part of what it means to listen with a hearing loss. Hearing is something that happens without us being aware of it taking place. Listening, however, is active. It is something we ‘do.’ When listening conditions are favorable this happens easily and we are not aware of the effort involved.

However, when conditions are challenging, such as listening with a hearing loss, a listener is required to do additional mental work to enable them to understand speech, music or identify sounds in the environment.

If recipients expect to listen in the same way as hearing family and friends, they may be putting a lot of added pressure onto themselves. The extra pressure is stressful and can actually be counter-productive. Listening well may be possible in short periods, but over longer periods can become exhausting and can quickly lead to fatigue.

The good news is that recipients tell us when they make the effort to listen with their cochlear implant (s) that they feel a greater sense of social connectedness – the feeling of being in close personal contact with the world around them.

Cochlear™ CoPilot helps with strategies for the holidays

There are a number of strategies that can help manage your recipients’ energy levels for listening. Cochlear CoPilot is a mobile app that features information and insights from experts plus advice from other recipients.

Here are some tips for your patients from Cochlear CoPilot to get started:

  1. Recognize that listening with hearing loss requires effort.
  2. Schedule breaks in advance for times when you know that listening will be intensive or challenging.
  3. Allow yourself downtime to give your brain a listening break. Spend some time doing activities that don’t require you to listen very much – read, exercise, or meditate.
  4. Plan your day so that challenging tasks and activities are scheduled when you have the energy.
  5. Remember that good nutrition and adequate sleep play an important role in managing your energy.
  6. Take a short break when you find yourself straining to listen. This could happen at work, during meetings, social events or even when you are simply tired.
  7. Step away and tune out to reduce stimulation and help to de-stress and refresh.
  8. Prioritize activities that are most important to you during the holiday season such as family get togethers or social events. This will help ensure that you have enough energy for those listening-based activities that are special.

While it might not always be possible to fully schedule the day around upcoming listening demands, having an awareness that listening effort can impact energy level means they will be more likely to take a break from listening when applicable. Planning in advance enables your recipients to be at their best when listening really matters.

To find out more about listening effort, preventing listening fatigue at the holidays and practical tips from other recipients, download Cochlear CoPilot.

About the author: Dr. Hughes is currently a Research Fellow at the Centre for Patient Reported Outcome Research (CPROR) at the Institute of Applied Health, University of Birmingham in the UK. She received her M.H.Sc in speech-language pathology from the University of Toronto, Canada, and her PhD at Swansea University Medical School, Wales, UK where she was a James Callaghan Scholar whose research focused on the development and validation of a new patient-reported outcome measure of listening effort in adult cochlear implant recipients.  Dr. Hughes has worked on several collaborations with the Australian Hearing Hub and the Australian Institute of Health Innovation, Macquarie University, Sydney, Australia, and she is a Core Member of the Adult Rehabilitation Special Interest Group, British Society of Audiology.

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Dr. James Connor Sullivan

Professional perspective: Hear from an AuD and recipient on best practices

February 4, 2021

James Connor Sullivan, AuD, CCC-A, F-AAA, discusses his experience as an audiologist and recipient, as well as the future of the cochlear implant industry.

How did your experience as a recipient draw you to the field of audiology?

Dr. Sullivan: As a child, my family always raised their kids that they would have to go to college after graduating high school. As the only person with hearing loss in my family, I was treated no differently. I went through all of my grade school with bilateral hearing aids, and it wasn’t until college that I became a candidate for a cochlear implant.

Prior to getting a cochlear implant, I actually never wanted to be an audiologist. When I was in high school, I always thought I wanted to work in a theater program working behind the scenes as a lighting technician, so I enrolled into a selective theater program in Oklahoma. It was during my first semester of my undergraduate program that I had a pretty significant hearing fluctuation, making me a candidate for a cochlear implant.

As an avid researcher of everything technology, I turned to the web and anything else I could get my hands on to get any information I could about the cochlear implant process, trying to figure out “what a cochlear implant sounds like.” It very quickly became apparent to me that getting good, reliable and accurate information for young adults about cochlear implants is very difficult.

Most young adults with hearing loss are in an awkward stage of their life (for many reasons). Most young adults are trying to figure out their financial situations, career goals, health insurance coverage, how to pay for hearing technology as they are losing coverage, all in the midst of possibly transitioning out of their pediatric audiology clinic and into their adult audiology clinic with a new provider.

I was young, broke, unhappy with my major as a freshman, unable to afford healthcare or new hearing aids, and my hearing had a pretty significant shift in my hearing and word understanding. As part of the cochlear implant approval process I realized that I had a unique insight that most people rarely get to experience or share with their patients.

The day I got activated with my cochlear implant I changed my major from theater to audiology because CI audiologists get to change our patients’ lives every day. I always knew I wanted to do something that had a true impact in others lives and little did I know how much I’d love getting to do it.

 How has the current global environment changed the way you deliver care?

Dr. Sullivan: COVID-19 has thrown a wrench in 2020. I think that the pandemic has made providers think about each procedure and process, and ensure that what we are doing is beneficial to the patient and to the office as a whole. As part of this review, I believe that we have found some things to increase the efficiency of our clinic to help make a lasting change in the patient experience.

  1. Prior to COVID-19, our clinic utilized primarily paper case histories. We have now moved to all digital, allowing for appropriate triaging of patient appointments and for our clinical assistants to move up appointments as medically indicated.
  2.  As face masks are required in all clinical spaces, we have expanded the use of voice-to-text software throughout our iPads® for our patients with significant hearing loss or language barriers.
  3.  We have added virtual appointments for any and all appointments that have the ability to be conducted virtually, including device selections and counseling appointments.

 How do you empower patients to achieve hearing goals and outcomes?

Dr. Sullivan: We have all of our cochlear implant patients establish care with an auditory verbal therapist to assess their needs and set appropriate goals. From an audiology standpoint, it is important to educate the patient, but not over-educate them on all of the intricacies of their equipment. It is VERY easy to get overwhelmed the first day.

At my activation appointments, I tell the patients that they need to “focus” on three things during their first few days with the device, adding more layers of complexities as I see the patient for their follow-ups.

1.       How to change the battery and put the device on.

2.       Focused listening therapy, at least 20-30 minutes a day.

         My go-to apps are AngelSounds™ and Bring Back the Beat. Later I encourage audiobooks.

3.       Progressing through the progressive MAPs.

I typically set a schedule for when to progress, every two days progress to the next MAP. By the next time I see them they’ll be on the appropriate MAP.

At the end of the day wear time and auditory stimulation is the name of the game. As the patient comes for their follow-ups and they display that they have an appropriate grasp of the first concept, then I’ll add in information like accessories.

Is hearing therapy involved?

Dr. Sullivan: In order to ensure the patient has appropriate access to sound, we always check Ling Sounds during their MAPping to ensure an appropriate MAP has been completed. Once appropriate access to all the Ling Sounds has been established, the patient needs to establish care with hearing therapy.

Hearing therapy is an integral part of our cochlear implant team. As previously mentioned, we have established our patients with our auditory verbal therapist in the area. We also encourage at-home exercises and show them in the clinic to ensure understanding of the tools.

How are outcomes and quality-of-life measured?

Dr. Sullivan: We measure outcomes through the SSQ, the Tinnitus Handicap Inventory (if they have Tinnitus) and the Nijmegen Cochlear Implant Questionnaire. These are administered through an online survey site on an iPad. In addition, we regularly assess our patient’s performance through functional testing with CNC and AzBio (in quiet and in noise as appropriate) testing.

Can you touch on awareness/access to care in the cochlear implant industry?

Dr. Sullivan: It’s no secret that cochlear implants are significantly underutilized by patients who could benefit from them. I think that the 60/60 guideline (Zwolan et al. 2020)1 should really be in every clinician’s mind when conducting any audiological examination.

If a patient has less than or equal to 60% word recognition in either ear, or if their pure tone average is at or less than 60 dB HL for either ear, a clinician should refer the patient for a cochlear implant evaluation. It is important to stress that just because you get evaluated for a cochlear implant, it does not mean you are receiving a cochlear implant. I always look at these appointments as information gathering sessions.

Per Zwolan et al. 2020, if utilized as a screening guideline this screening has a 96% detection rate and a 34% false positive rate.

It is important to educate fellow clinicians, providers in the area and patients about the ever-changing cochlear implant landscape. 

What excites you the most moving forward in the CI industry?

Dr. Sullivan: I’m most excited about the expanded access to this life-changing technology. As previously mentioned, I never would have even considered being an audiologist and now I get to work with cochlear implant patients every day. I’m looking forward to the evolution of cochlear implant processor technology and providing access to patients who otherwise would have never received access to this technology.

For more helpful resources, subscribe to the Cochlear ProNews.

About the author: Dr. Sullivan is an audiologist who works in the Houston area with patients who have hearing loss. Dr. Sullivan, also born with a hearing loss, enjoys using both his personal and professional experiences with his cochlear implant and hearing aid to aid in the treatment of his patients. Dr. Sullivan has presented both nationally and internationally on several topics, including Large Vestibular Aqueduct Syndrome, the disorder that resulted in his hearing loss. He is passionate about using his personal experiences alongside clinical knowledge in audiology to help patients across the lifespan and their families who are impacted by hearing loss.   

References:

  1. Zwolan, Teresa A.; Schvartz-Leyzac, Kara C.; Pleasant, Terrence Development of a 60/60 Guideline for Referring Adults for a Traditional Cochlear Implant Candidacy Evaluation, Otology & Neurotology: April 20, 2020 – Volume Publish Ahead of Print – Issue – doi: 10.1097/MAO.0000000000002664

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