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BackTable / ENT / Article
Complex Causes of Pediatric Hearing Loss: Auditory Neuropathy, CMV & Bacterial Meningitis
Iman Iqbal • Updated Sep 27, 2024 • 35 hits
Pediatric hearing loss can arise from various complex causes, with conditions like auditory neuropathy, congenital cytomegalovirus (CMV), and bacterial meningitis each presenting unique challenges and individualized treatment considerations. This article explores the diverse causes of pediatric hearing loss and the tailored approaches needed to manage them, as explained by otolaryngologists Dr. Rachel St. John and Dr. Walter Kutz on the BackTable ENT Podcast. You can listen to the full podcast below.
The BackTable ENT Brief
• Auditory neuropathy is a variable hearing disorder where sound reaches the brain but is not processed typically, leading to fluctuating hearing outcomes.
• ABR is a key tool in diagnosing auditory neuropathy, often revealing abnormal mirrored waveforms.
• Auditory neuropathy may improve in some children as their auditory systems mature, but in others with significant brain damage, such as from hypoxic-ischemic encephalopathy (HIE), the condition is often permanent.
• Congenital cytomegalovirus (CMV) infection, especially when contracted by the mother in early pregnancy, can lead to hearing loss in newborns or delayed-onset hearing loss later in life.
• CMV-related hearing loss often goes undetected by newborn hearing screenings, necessitating regular follow-up testing, particularly between two and three years of age when symptoms typically arise.
• Bacterial meningitis can lead to rapid cochlear ossification (labyrinthitis ossificans), requiring urgent cochlear implant placement to prevent permanent hearing loss.
• Early detection and intervention, including the use of cochlear implants, are critical for children with hearing loss from bacterial meningitis to avoid the challenges posed by cochlear ossification.
Table of Contents
(1) Auditory Neuropathy
(2) Hearing Loss in CMV-Infected Children
(3) Hearing Loss in Bacterial Meningitis
Auditory Neuropathy
Auditory neuropathy is a complex and highly variable hearing disorder where sound reaches the brain but isn’t processed in a typical way, leading to unpredictable hearing outcomes. This condition can be identified through abnormal auditory brainstem response (ABR) patterns, which often show a mirrored waveform in certain testing conditions. Acoustic reflexes may remain intact in auditory neuropathy.
The unpredictability of auditory neuropathy makes it particularly challenging for both families and clinicians. Children can have "good" and "bad" hearing days, with their auditory processing capabilities fluctuating from one day to the next. Managing parent expectations is one of the most difficult aspects of auditory neuropathy because the disorder’s effects can vary so significantly from one child to the next. Some children may benefit from hearing aids, while others may not, despite having similar behavioral thresholds. Decisions regarding cochlear implants for these children require careful consideration and consultation with pediatric audiologists, who play a crucial role in interpreting how well the child responds to sound.
In some cases, auditory neuropathy may improve as a child matures, particularly in children who experience cortical maturation around 15 to 18 months of age. However, in children with significant brain damage from conditions like hypoxic-ischemic encephalopathy (HIE), the damage to the auditory processing centers is usually permanent, and improvement is unlikely. Counseling families is difficult because the progression of auditory neuropathy can be unpredictable, and parents often receive mixed messages from different healthcare providers. Comprehensive evaluations, including behavioral testing, are critical, and hearing aids are often tried before considering cochlear implants. However, every decision must be individualized, as no one-size-fits-all solution exists for children with this condition.
[Dr. Gopi Shah]
All right. Can we talk a little bit about the auditory neuropathy kids? I would love to-- If you could just explain that to us, and then are these kids different in your mind?
[Dr. Walter Kutz]
Yes, I can. Oftentimes these kids will come over because they're potentially a cochlear implant candidate. Like Dr. St. John said, they're going to have oftentimes intact acoustic reflexes. They're going to have abnormal ABR. Oftentimes the ABR will show a mirroring when you change the rarefaction condensation, they'll mirror each other. There's this distinct pattern, for classic auditory neuropathy that's seen. I think an important thing to remember is that sometimes kids can be born with auditory neuropathy and then it'll actually improve.
These kids we'll definitely go a little bit slower if we're going to consider cochlear implants and they're very carefully followed by audiology, and frankly the audiologists are experts at this. I really listen to their interpretation of how their child's doing as a team and we'll talk about this later, we get together and decide, is a cochlear implant in the best interest of this child. I think auditory neuropathy definitely makes it more interesting and challenging, for those kids, especially.
[Dr. Rachel St. John]
I agree. I think from a parent expectation point of view, this is probably one of the most challenging things that comes through my clinic. Because by nature, AN is very idiosyncratic. Every child looks a little different in terms of how they're-- It's cortical level hearing processing. The sound gets to the brain, but then there's-- It's not always processed the way that we would expect. Not only do these kids look different from each other, so you might have one kid who doesn't benefit from hearing aids and one that really does and their behavioral thresholds look fairly similar, but these kids can actually look different from day to day.
Parents will classically describe having good hearing days and bad hearing days and that is the absolute nature of AN. It's its own thing. I think in terms of counseling parents of what to expect, that's much more difficult, because we don't always know what to expect. We don't know if the character of that's going to change, as Dr. Kutz mentioned. If you have AN and you get cortical maturation, you may see that waveform change around 15 or 18 months of age. Whereas children who have like a really significant brain insult, like there are kids with really severe hypoxic-ischemic encephalopathy, that's sound processing at a cortical level that's not happening. That's not going to improve because the insult is what it is, and then it's, for lack of a better word, fairly static after that. What parents expect is tough.
Then I think what happens is parents sometimes get very mixed messages from different providers. That has been one of the bigger challenges for me in working with these families. I had a family, there was an audiologist, it was an outside audiologist who said, "Oh, well, your kid needs a cochlear implant because those kids always do better with a cochlear implant." While we know that sometimes the quality of the input with a cochlear implant might be better than what they get through hearing aids, this is a kid whose behavioral thresholds were testing in the mild to typical range. We just knew that the message wasn't the standard message. They still had that AN waveform. That's not somebody who would even qualify for a cochlear implant.
[Dr. Gopi Shah]
Do you refer these kids for hearing aid evaluation? What are their resources or options? What counseling do you, or resources can you provide these patients?
…
[Dr. Rachel St. John]
Absolutely. These kids often will benefit from hearing aids. It's just a question of, is the quality helpful for them? Some of these kids, it is, and some of them, they're not. In talking with our audiologists, the goal is always to-- For anybody who's even considering a cochlear implant, we always see benefit to hearing aids first. That's part of the picture. For these kids in particular, it's really important to see how they do with hearing aids. One of the things that the audiologists and I have talked about a lot is that if they're going to program, they really need behavioral thresholds. You can't really get good threshold information off an ABR when you have auditory neuropathy. You can't state for sure, this is the level of hearing that I'm testing today. That really has to come from a behavioral evaluation.
…
[Dr. Gopi Shah]
You have to have that suspicion to test for it, to get the ABR, you know what I'm saying? If you have a kid that their behavioral testing looks pretty good, but yet there's report of problems or hearing loss, someone has to be like, oh, maybe this is auditory neuropathy and we should get an ABR, or no, am I thinking of this wrong?
[Dr. Rachel St. John]
I think the way it bears out practically, it's the opposite, which is you have kids who, based on either the fact that they're a baby and they can't behave early test, or they have some condition, HIE, seizure disorder, microcephaly. Something that's going to potentially cause AN situation, kernicterus. Those kids also often can't condition if they're older to behavioral testing. By default, you end up with an ABR to get accurate information. I don't know, Walter, if you've had a different experience with this, but most of the time, the ABR information comes necessarily with these kids, because it's really the only mechanism that we've had to get a full evaluation on them.
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Hearing Loss in CMV-Infected Children
When managing hearing loss in children with conditions such as congenital CMV, the timing of the mother's infection during pregnancy significantly affects the child's outcome. Early infections, especially in the first trimester, often lead to clear symptoms at birth such as low birth weight, jaundice, and hearing or vision problems. These cases are easier to detect, but CMV infections later in pregnancy present challenges, as hearing loss may develop later in life, making newborn screenings insufficient for identifying all cases.
Managing these cases requires frequent follow-ups and a tailored approach. Children diagnosed with CMV may undergo behavioral audiology testing every three to six months, particularly around the age of two to two and a half years, when hearing loss typically manifests. Testing methods vary based on the child’s ability to cooperate and the severity of their symptoms, ranging from behavioral audiometry to ABR under sedation. For children with other developmental delays, more aggressive testing, including ABR, may be necessary to ensure accurate results. The difficulty of early identification and tracking of CMV-related hearing loss is compounded by the lack of universal screening for CMV in newborns. Although early identification allows for interventions like ganciclovir therapy to slow the progression of hearing loss, the logistics of widespread CMV testing, especially for delayed onset and/or asymptomatic children, remain a significant challenge.
[Dr. Rachel St. John]
CMV is tough for a number of reasons. Congenital cytomegalovirus, it's every place in the United States right now, in all of our 50 states, because we handle things at the state level, it's all being handled differently. A lot of it depends on what's been put in front of the legislature based on what's been happening.
The thing about CMV that's so tough. If it's the neurologic presentation for CMV, all depends on when the mother contracted CMV during her pregnancy. If it's an early, like first trimester infection and she did not have native antibodies, if it's the first time she's seen CMV, that baby will usually come out. People will mostly know that the baby likely has CMV. They're small, they have problems with clotting, they have terrible problems with jaundice. They often have vision, hearing. There's a whole host of symptoms that go along with that.
The tricky part is the later, the closer to the third trimester infection, because while those babies sometimes are born deaf or hard of hearing, it is much more common for that to be a delayed onset phenomenon. That's where screening gets tricky. UT Southwestern, very fortunately, was part of this study back in 2007 called the CHIME study. I think there were six or five or seven centers, but we were one of them. Where basically from 2007 to 2012, so it was a five-year period, every child that did not pass a newborn hearing screening in our hospital system, and that included Parkland, got a PCR test for CMV at birth. That was almost 100,000 kids by the end of the study. It was 999 something.
They looked at all those kids who didn't pass their newborn hearing screening and saw how many of them had congenital CMV and it was an extremely low number. It was 0.4%. It's translated to 400 some kids out of 100,000. The problem with that is, first of all, you only catch the kids who are presenting as deaf or hard of hearing. It caught about, it was close to 60% of them, but the other 40% are kids who had CMV and they were delayed onset. The newborn hearing screening wasn't your pathway to figuring out who those kids are.
The much bigger problem is that CMV is ubiquitous in the community. If you look at Karen Fowler's data, she's an ID professor at University of Alabama, and she has done a ton of publications on congenital CMV. If you look at her data and you look at the CDC data, it's around 8 to 12%. If you split the difference, 10% of kids who are completely asymptomatic who have CMV go on to develop delayed onset hearing loss. If you look at the number of those kids, if you look at the incidence of CMV in the general community, it's one in 200, it's really high.
…
The delayed onset stuff is really tough, especially in the sort of toddler pre-K group, because really you're looking for concern about responsiveness and lack of expressive language delay. That can be not picked up. That can be really tricky. It can be minimized. It can be overlooked. It can be denied. CMV is challenging, but if we know about it in the newborn period and they're symptomatic, that can change our management. Some of those kids will qualify for ganciclovir treatment, which has-- And I'm not a super guru with the ganciclovir studies, but there's been enough data to show that can ameliorate some of the progression with the hearing.
We've definitely had patients who have been identified early and have gotten ganciclovir therapy, and have gone on with frequent testing to see how that has affected their hearing.
[Dr. Gopi Shah]
Does that identification happen because they failed their newborn hearing screen and so then they get the blood test?
[Dr. Rachel St. John]
It only happened in the context of the CHIMES program. Universal CMV screening is almost nowhere, because it's a huge undertaking in terms of money and then linking that to newborn hearing screening. Targeted testing, which is what the CHIMES program did, I think philosophically we love it, but when you look at the data, it caught 0.4% of kids who didn't pass their newborn hearing screening. That's not winning over people who are planning budgets. That's not something that's making people run to fund newborn hearing screening protocols and testing for CMV in those patient populations. The American Academy of Pediatrics just last month established a CMV committee that I have joined because for just this reason, it is really tricky. It's tough to get funding, but we know what the longitudinal implications are. We're all very passionate about it. It's just figuring out realistically how to make that happen in a coordinated way. It's very challenging.
…
I believe the way we handled it through the CHIMES program is that those children were followed up with audiology every three to six months to see, at least in those first three years of development. I think it was a combination of both screening and testing just to get as much data. If a kid had an atypical screen and they were too young for behavioral testing, that would buy them an ABR. If they were old enough to behavioral test, they would try to get as much data there.
They were followed very closely by audiology for several years. I think the average age of hearing loss in this patient population for kids who have delayed onset is between two and two and a half years old. That's a tough time. Also, language-wise, what's going on there? The kids are frustrated because they don't have enough language if they're hearing and there's so much development that's happening. They were followed very closely for several years as part of that study.
Certainly, if we have kids and we know that they had congenital CMV, I tend to make sure those kids are plugged in with audiology pretty frequently. If they go to audiology and they'll always write their recommendations, it's always come back within three months, six months. It's never, "Oh, we'll see you next year," because that often is a moving target.
[Dr. Ashley Agan]
In terms of screening, are we talking about behavioral sound field, OAEs, and temps, or hey, I can't get behavioral sound field because I can't get the baby to condition at 10 months? I have normal temps and OAEs, that's sufficient? Are we talking now, hey, we might need an ABR and this might need to be under anesthesia because the baby doesn't nap anymore. What's the minimum amount of screening do you feel for the CMV babies is adequate?
[Dr. Rachel St. John]
That's tough. I think that part of it is you have to look at your individual kid. If you've got a kid who has signs of developmental delay, I'm not going to be messing around with acoustic reflexes. I'm going to want full ear-specific data on that child because that's going to affect, are we using hearing aids, what education plan, what kind of ECI support, you want to know.
For kids who are asymptomatic, we happen to know that they have congenital CMV and they have typical OAEs, they're seeing them and they're doing screening, and that kid is developing normal language, that would probably be a little less likely to push into a sedated ABR just to know what was happening. Again, for those kids that are-- in my clinic, it doesn't matter if we're talking about CMV or not. If you've got expressive language delay, I need your specific information.
I think when we've had kids who have had sound field testing for three years and haven't been able to condition and they've got language delay, I'm like, "That kid needs an ABR. We need to know what we're working with. We're only getting information on the better hearing ear."
Hearing Loss in Bacterial Meningitis
Bacterial meningitis can lead to severe-to-profound hearing loss, while viral meningitis usually does not have this effect. Children with bacterial meningitis are often critically ill, and the primary concern is stabilizing the child and preventing neurological complications. Once the child is stable, early hearing tests are essential, often performed with an ABR. If a child is diagnosed with severe-to-profound hearing loss due to bacterial meningitis, cochlear implantation should be performed as soon as possible, ideally within a week or two.
Detecting hearing loss promptly is critical because bacterial meningitis can cause labyrinthitis ossificans, a condition where the cochlea hardens (ossifies) within weeks. This ossification can make cochlear implant placement difficult and lead to poorer outcomes, as the cochlea may need to be drilled out to insert the electrodes. Although not all children with bacterial meningitis develop labyrinthitis ossificans, those who are seriously ill or show signs of hearing loss require urgent attention. Even children with milder cases or moderate hearing loss should be monitored closely, typically with hearing tests every four weeks, to ensure their condition does not worsen. While cochlear implants for bacterial meningitis are rare—only occurring once or twice a year at major centers—they are crucial for those who need them due to the risk of rapid ossification.
[Dr. Ashley Agan]
Walt, let's talk about the meningitis picture, the child with meningitis. Tell us, with meningitis, the infection can lead to hearing loss. While they're in the hospital, many times they'll get an audiogram and you might have a child that has moderate to severe bilateral hearing loss. What are the next steps? When do you see these kids and what is your thought process in terms of if we are going to need to think towards a cochlear implant?
[Dr. Walter Kutz]
Bacterial meningitis can certainly cause severe-to-profound hearing loss. Viral meningitis typically does not do this. It's going to be bacterial. The kid's going to be very sick in the hospital. Oftentimes, the first goal is to make sure the child survives the infection, and doesn't have any neurological complications. Oftentimes, these kids are really sick. Once they're stabilized and we recommend testing, a lot of times that may have to be an ABR because they're not going to be neurologically responsive.
It's really important to identify hearing loss very early because they can develop labyrinthitis ossificans, which is where the cochlea can ossify. This can happen within weeks very quickly, within two or three weeks even. If we identify a child with bacterial meningitis that has severe-to-profound hearing loss, we'll try to place a cochlear implant as soon as possible that week or the next week if we can.
The problem is if it's delayed and they've had meningitis, they develop labyrinthitis ossificans, placing a cochlear implant can be very difficult. As a matter of fact, you may even have to drill out the cochlea and just lay the electrodes into what's left of the cochlea after doing that. Those results are definitely inferior to what you would get by placing a cochlear implant before ossification. There's definitely a timeline that's critical for a patient with bacterial meningitis.
[Dr. Ashley Agan]
Is that common for patients to get labyrinthitis ossificans? Is that happening to most meningitis patients?
[Dr. Walter Kutz]
No, that's not most patients. That's typically the really sick patients, but even patients that they're recovering from bacterial meningitis that maybe weren't as sick as others, they definitely need testing quickly. They need to be followed at probably regular intervals. Typically, that may be every four weeks for a while, especially if there's a mild hearing loss or moderate hearing loss after bacterial meningitis, you want to follow those kids very carefully to make sure their hearing loss isn't progressing.
We don't see it all that often. I would say once or twice a year, if even that, we have a child we do a cochlear implant on because of bacterial meningitis. Obviously, at Children's Medical Center, there's many kids that have bacterial meningitis. It's not that common, but it's something we should be aware of.
Podcast Contributors
Dr. Rachel St. John
Dr. Rachel St. John is a practicing ENT and Associate Professor of Clinical Medicine at Children's Medical Center Dallas/UTSW Department of Otolaryngology.
Dr. Joe Walter Kutz
Dr. Joe Walter Kutz is a neurotologist and Professor of Otolaryngology and Neurosurgery at the University of Texas Southwestern Medical Center in Dallas, TX.
Dr. Gopi Shah
Dr. Gopi Shah is a pediatric otolaryngologist and the co-host of BackTable ENT.
Dr. Ashley Agan
Dr. Ashley Agan is an otolaryngologist in Dallas, TX.
Cite This Podcast
BackTable, LLC (Producer). (2021, February 16). Ep. 16 – Congenital Hearing Loss [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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