Hearing loss and Cochlear Implants

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In this episode Dr Gavin Nimon ( Orthopaedic Surgeon) interviews Dr Paul Varley (ENT Surgeon) on the treatment of hearing loss and Cochlear implants. The invention known colloquially as the bionic ear has revolutionised hearing for a large number of people and we get more of an understanding of its indications and how it works.

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Transcript

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Dr Gavin Nimon: [00:00:00] As a podcaster and someone who loves music, the ability to hear clearly is something that's extremely important to me, as it is for all Australians. And yet the Australian Government estimates that 3. 6 million people are affected by hearing loss.

Dr Gavin Nimon: Whilst the evolution of hearing aids has had a huge impact on the treatment of this condition, it's not suitable for everyone, in particular those born with congenital hearing loss. Today we're going to learn more about what a cochlear implant actually is, how it works and who it's useful for. G'day and welcome to Aussie Med Ed.

Dr Gavin Nimon: The Australian Medical Education Podcast. A program born during COVID times to emulate that general chit chat and banter around the hospital with the idea of educating the medical student and GP alike. I'm Gavin Nimon, an orthopaedic surgeon based in Adelaide, and it's my pleasure to bring Aussie Med Ed to you.

Dr Gavin Nimon: And today we're joined by Dr. Paul Varley. He's an ENT surgeon from Adelaide. He graduated from the University of Adelaide in 1989, having completed ENT surgical training in 1999. He worked at the Flinders Medical Centre until 2016 as a consultant ENT surgeon. Paul is the co founder and director of the South Australian Cochlear Implant Centre, which has been established since 2005.[00:01:00] 

Dr Gavin Nimon: We're looking forward to hearing what Paul has to tell us about hearing loss and how the use of cochlear implants have changed many people's lives. I'd like to start by acknowledging the traditional owners of the land on which this podcast has been produced, the Kaurna people, and pay my respects to the Elders, both past, present and emerging.

Dr Gavin Nimon: It's my pleasure now to introduce Dr. Paul Varley. He's an ENT surgeon who trained in Adelaide and also the director of the South Australian Cochlear Implant Centre. He's going to talk to us about hearing loss and the cochlear implants in particular. Welcome Paul. 

Dr Gavin Nimon: Thanks Gav, thanks for having me. Thanks Paul, thanks for being involved in Aussie Med Ed.

Dr Gavin Nimon: Hearing loss is something that's quite common actually, particularly amongst my surgical colleagues in orthopaedics. Tell me, how many people in Australia are actually affected by hearing loss?

Dr Paul Varley: According to recent population studies, probably about three and a half million people in Australia have some form of hearing loss.

Dr Gavin Nimon: Well that's a huge number, and I believe a lot of people actually develop as they get older in life as well. Perhaps you could describe what types of hearing loss there are. 

Dr Paul Varley: Well, we divide it really into what we call conductive or sensory neural primarily. So, with conductive hearing losses, I guess we're talking about [00:02:00] the conduction mechanism to get sound to the cochlea or the inner ear.

Dr Paul Varley: So, Problems with the ear canal, problems with the eardrum, the middle ear space or the ossicles. So the ossicles are the three bones that are attached to the eardrum that carry the sound across the middle ear space to the cochlea. So problems with any of that mechanism that is conducting sound to the cochlea are called conductive hearing losses.

Dr Paul Varley: If there's a problem with the cochlea or the nerve itself, so the cochlea is where the waveforms are converted to neural impulses and passed on the nerve to the brain. Problems in that area we call a sensory neural hearing loss. And really they, they're, they're quite different causes and they're treated in different ways.

Dr Paul Varley: Probably the majority of hearing loss in Australia is, well, it is acquired. Congenital hearing losses are a relatively small number comparatively. 

Dr Gavin Nimon: Okay. So does sensory neural loss affects predominantly the nerve itself or actually the sensory mechanisms such as the cochlear? 

Dr Paul Varley: Really with cochlear implants, we're talking about cochlear hearing losses, so problems with the hair cells rather than the nerve itself.

Dr Paul Varley: So. Auditory neuropathy, which is another form of sensory neural hearing loss, I guess, is much rarer, thankfully, and we don't really have a great understanding of the causes there. And they don't tend to do as well with cochlear implants, though they can get some benefit, but really with cochlear implants, we're talking about problems within the cochlea and the hair cells specifically.

Dr Gavin Nimon: And which part of the sensory mechanism is actually affected by acquired hearing loss, i. e. hearing loss of age? 

Dr Paul Varley: It's predominantly in the older age group. It's a sensory neural hearing loss associated with loss of the hair cells in the cochlea. The nerve is usually working satisfactorily in most cases, which is good because that's what we need for the cochlear implant to work.

Dr Gavin Nimon: What causes the loss of the hair cells themselves? Does it relate just purely to aging or is there other drugs that maybe you've consumed that actually affects it as well? 

Dr Paul Varley: There's a whole range of causes, Gav. It can be genetic, it can be environmental factors, viral infections, poor blood supply, just age related deterioration, drug toxicity.

Dr Paul Varley: I mean, the list goes on and on, but I mean, the commonest cause that we see in the adult cochlear implantation is just age related degeneration. 

Dr Gavin Nimon: [00:04:00] That's certainly a large list. What about smoking or alcohol intake? Does that affect the damage to the hair cells themselves? 

Dr Paul Varley: Uh, no, it's predominantly ototoxic medications, gentamicin, those sort of things.

Dr Paul Varley: Some of the chemotherapeutic agents are thought to cause sensorineural hearing losses. I mean, we don't really have a clear understanding of the cause of degeneration. I guess things like smoking and poor general health and poor blood supply may all have an effect, but just with perfusion of the cochlear, I guess.

Dr Gavin Nimon: And how does the loud noise affect it as well? I mean, what happens there, does that just damage the hair cells themselves?

Dr Paul Varley: Yeah, it does. Prolonged and repeated noise exposure will result in a sensorineural hearing loss. And interestingly, it's maximally around four to six kilohertz, so in the higher frequency range.

Dr Paul Varley: So often what will happen, someone will have a noise induced hearing loss from occupation or music or whatever, which gives them a moderate loss. And then as they age, they get the age related hearing loss on top, which will push them into a more difficult area. 

Dr Gavin Nimon: so 4-6 kilohertz is actually quite high, as a surgeon in theatre using a sucker, you always wonder whether the sucking noise is actually causing that sort of damage to the hearing from that particular high pitch noise.

Dr Paul Varley: I don't think so. I think some of the dentists back in the days when they were using high speed drills used to get a hearing loss associated with that, but I think the general noise exposure in theatre is, is well, probably fairly low. You are an orthopaedic surgeon, so you do swing a big hammer Gav, that might make a bit of noise, but generally speaking, no, I don't think noise in theatre would be a huge issue.

Dr Gavin Nimon: OK so once someone develops hearing loss and notices they're not hearing quite so well, what are the steps taken in assessing the patient, diagnosing and then treating 

Dr Paul Varley: it? Well, in the first step is obviously history and examinations, having a look in the ear and see if you can see any pathology with Sensorineural hearing losses, obviously you can't, with a lot of the conductive hearing losses you may see pathology in the drum, but the key to it really is getting an accurate hearing test done, so we do what's called an audiogram where we measure their thresholds for hearing, and then there are techniques with the audiogram that we can separate out the conductive from the sensorineural, and then I guess once you've quantified the degree of hearing loss and the cause, you come up with a management plan which will vary depending on the type and the severity of the hearing loss.

Dr Gavin Nimon: And how do you actually quantify the level [00:06:00] of hearing loss? Do you base it on decibel levels or other factors? 

Dr Paul Varley: Decibels at each frequency, so we measure routinely from about 250 hertz up to about 8 kilohertz and basically what you do is you start loud and you get softer in each ear at each frequency and find the level at which the cursor being tested last records a response.

Dr Paul Varley: Most people with normal hearing will hear sounds at 20 decibels or softer. And its divided into normal, mild, moderate, severe and profound hearing losses. So normal is 20 dB or better. Mild hearing losses, their thresholds are in the 20 to 40 decibel range. Moderate 40 to 60. Severe 60 to 80 decibels. And profound, anything above 80 decibels.

Dr Gavin Nimon: Okay, a question someone might ask is that once they start developing hearing loss, is there anything they can do to try and slow down or prevent hearing loss? Are there any tablets or drugs they can take to restore their hearing? 

Dr Paul Varley: Not really. I don't think there's any sort of intervention that people can do to change the level of their hearing loss or their speech perception without either having surgery to correct a problem, [00:07:00] treatment of any conductive losses, hearing aids, and for more severe cases, cochlear implants.

Dr Gavin Nimon: Okay, so at what level of hearing loss do you start considering seeking treatment or using hearing aids? 

Dr Paul Varley: There's no absolute answer, but I mean, the short answer I say to my patients is, are you having issues communicating with family, friends and colleagues? But generally speaking, once they start getting a moderate loss at two kilohertz and above, I think it's time to think about trialing hearing aids in the first instance.

Dr Paul Varley: But some people will manage quite well with a mild. Well, mild to moderate hearing loss, but other people have a significant impact on their function, both socially and professionally. So that's, you know, a question I always ask is, what actual impact is their hearing loss having on them? And the other thing particularly I try to point out to people is that once they're getting a moderate hearing loss, there's evidence that if you do wear hearing aids and some amplification does help maintain your auditory pathways to some degree.

Dr Paul Varley: So there is some benefit, not only with communication, but with preservation of hearing to wearing, hearing aids once you start developing a reasonable loss

Dr Gavin Nimon: [00:08:00] Excellent. Well, as you said before, the hearing loss affects different frequencies to a varying amount. Does that mean that hearing aids can be adjusted so that varying frequencies can be adjusted to be increased in certain levels, ie. those frequencies that aren't having as much of an impact can be raised up more, and the ones that actually aren't affected as much don't need to be amplified as much? 

Dr Paul Varley: Yeah, absolutely. I mean, the early hearing aids just amplified everything, so, uh, you get benefit where you had a hearing loss and distortion where you didn't, but modern hearing aids are very programmable and frequency specific, so that can be set up to the individual's loss and of course you get significantly better results with that.

Dr Paul Varley: So, that's actually done by hearing aid providers who are audiologists, that's a whole different skill set basically to get a hearing aid set up properly. 

Dr Gavin Nimon: What are the sort of types of hearing aids you look at? Let's look at the progression from the very basic ones to the cochlear implants. 

Dr Paul Varley: Well, really there's  a behind the ear or in the canal hearing aids.

Dr Paul Varley: So behind the ear ones are the typical ones you see sitting over the pinna and there'll be a little tube going into the ear canal versus hearing aids that sit in the ear canal themselves and are less visible and [00:09:00] there are pros and cons to both, but a lot of it comes down to personal preference. With some of the more severe hearing losses, you do need a tight fitting hearing aid or a mould because you're having a to put quite a lot of gain or amplification through the device.

Dr Paul Varley: As far as the programmability, they're very similar. There's some newer hearing aids coming out that are called CrossAids, which are quite interesting. So if somebody has a total hearing loss in one ear, but reasonable hearing in the other ear, They can wear a hearing aid in both ears, and essentially the one on their severe hearing loss side picks up the sound and transmits it via Bluetooth to their good ear.

Dr Paul Varley: So, they don't get stereo sound, but they get 360 degree sound awareness, which is beneficial. 

Dr Gavin Nimon: So, I understand the next progression from a standard hearing aid either in the canal or behind the ear is a cochlear implant. What actually is this cochlear implant? How long have they been around for, and how do they actually work, Paul?

Dr Paul Varley: The initial work was done in France and the US in the 50s and 60s with what we call single channel cochlear implants. So one electrode was placed into the cochlea and they did get sound [00:10:00] perception but no speech perception because it was only a single frequency. The modern cochlear implant is a multi channel device so there are multiple electrodes that go into the cochlea.

Dr Paul Varley: And that was really developed in the 70s, in parallel really, by Graham Clark, who was the founder of Cochlear, and Ingeborg Hochmeyer, I think is the correct pronunciation, who company became Medel, which is an Austrian company. They really developed them simultaneously. The way they work is, the cochlear has a, what we call a tonotopic arrangement of the nerve fibers within the cochlea. So you can predict quite accurately at what point in the cochlea those nerve fibers or what frequency those nerve fibers respond to. So at the beginning of the cochlea, those nerve fibers are the high frequency sounds and the further you go through, you head towards the more low frequency sounds.

Dr Paul Varley: So because there's a predictable layout of the nerve fibers that respond to certain frequencies of sound, we know that when we put the electrode in roughly which electrode is going to [00:11:00] correspond to which frequency. So, there's the internal component of the cochlear implant, which is the electrode array that goes inside the cochlea, and there's a receiver package really that sits under the skin behind the ear, and that's the internal component of the cochlear implant.

Dr Paul Varley: The external component is called a speech processor. And it looks a bit like a hearing aid, but it's not a hearing aid. What it does is it picks up each sound as it comes in and breaks it down into its component frequencies. And then there's a little magnet and a transmitter, really. So there's no physical connection between the external and the internal component, but the external component will then send the necessary information to the internal part and tell it which electrodes to stimulate at what intensity for what duration of 

So it's electrical stimulation of the auditory nerve rather than acoustic hearing if that makes sense 

Dr Gavin Nimon:. That's amazing and how big are these implants that actually sit inside the cochlea? What's the [00:12:00] actual size and dimensions of it?

Dr Paul Varley: The electrodes vary in length and you'll choose them depending on the situation.

Dr Paul Varley: Anywhere from sort of 16 millimetres to 28 millimetres in length would be the range. And there are different electrodes within each company's product range but, uh, yes they're probably, I'm guessing, sort of 0. 6 to 1. 2mm would vary in diameter, but they’re very thin, put it that way, Gav. 

Dr Gavin Nimon: And there's obviously various companies that make these implants that you can choose from.

Dr Paul Varley: Well, there were four, there's now essentially three.

Dr Gavin Nimon: So these are obviously pretty impressive devices. How do you know when someone actually needs it or when it's required to be used instead of a normal hearing aid? 

Dr Paul Varley: I guess the first question is, when do you think about offering someone a cochlear implant assessment?

Dr Paul Varley: And it's when they get to the point that their hearing aids are provided with limited benefits. So a conventional hearing aid tends to run out of efficacy, I guess, once their thresholds get to 60 or 70 decibels [00:13:00] or worse. And predominantly, with most of our patients, it's the mid to high frequencies that have that severe loss.

Dr Paul Varley: So, you get to the point where you can't get clarity in those higher frequencies regardless of how much amplification you're putting in, and the higher frequencies is where you get a lot of the consonant sounds. So, if you start to miss the T's, the P's, the D's, and you're only hearing vowel sounds, you can hear the person speaking, but it's the consonants that really give meaning to the word.

Dr Paul Varley: And so if you're missing the consonants, you start to struggle. And I mean, I hear it all the time from, you know, my patients and their families when they're coming to see me because they're struggling with their hearing is that they start to withdraw and they don't like putting themselves in situations where they struggle to hear.

Dr Paul Varley: They stop going out, they stop going to family dinners and if they do go to the Christmas lunch, they kind of sit in the corner and no one speaks to them because it's too difficult. deleted. There's no absolute level of hearing where you say, this person needs a cochlear implant. But once they're starting to struggle with their hearing aids [00:14:00] and they're starting to have an impact on their quality of life, I think that's the time we need to start thinking about a cochlear implant assessment to see if they'd benefit.

Dr Gavin Nimon: Okay. For those patients that actually reach that stage, what does a cochlear implant assessment involve? 

Dr Paul Varley: Okay. So generally speaking, they'll be referred to see us by their families or by the hearing aid providers. Basic hearing tests, you get a rough idea of whether they may or may not be a cochlear implant candidate.

Dr Paul Varley: But if they've got a reasonably severe mid to high frequency sensorineural hearing loss and they report that they're having troubles, we'll do a more formal assessment of their hearing. And it's, I guess, a functional assessment. A normal hearing test is just hearing beeps or tones and responding to them, but we do what's called speech perception testing.

Dr Paul Varley: So, We test the patients with and without their hearing aids in, and we have standard sets of monosyllabic words, phrases, and sentences that we play to them with and without background noise, and we can get a very accurate assessment of their functional hearing performance to [00:15:00] speech with and without their hearing aids.

Dr Paul Varley: And once they get to a certain level of poor performance, we can be reasonably confident that they'll do better with a cochlear implant. So once they're sort of getting less than, say, 60 percent, If monosyllabic word's correct in their better hearing ear, we think probably they're a candidate. 

Dr Gavin Nimon: So if the patient decides they'd like to proceed with a cochlear implant, what then happens?

Dr Paul Varley: So they'll have an appointment initially with the surgeon and then usually a couple of appointments with our audiology colleagues who will do the initial assessment and the discussion I guess of the results and the potential benefits of a cochlear implant. We don't rush the process. There's usually two, three or four visits with the surgeon, the audiologist before making the decision.

Dr Paul Varley: And then once the decision is made, then proceed to surge, which I'm happy to talk about the surgical process if you want.

Dr Gavin Nimon: Yeah, that'd be great. It'd be interesting to hear what the surgery involves and are there any risks of the surgery or are there any potential complications of the surgery as well?

Dr Paul Varley: The surgery's changed a lot over the last 25 years I have been doing this  Gav. It was initially quite a big operation. [00:16:00] It used to take three or four hours, but over the last, you know, 10 or 15 years, we've progressed to more and more small incision surgery. And the surgical time now, with a straightforward case, it might take 45 minutes with a slightly more complex case, perhaps an hour and a half, but it's quite a quick operation.

Dr Paul Varley: And the incision behind the ear is only probably 50 to 60 millimeters in length. And some people have this perception that it's actually brain surgery. It's not brain surgery. We're going through the mastoid behind the ear. So it's tolerated really well, in all honesty. So the patient will have the operation, generally stay in overnight, go home the next day.

Dr Paul Varley: Pain's minimal, usually Panadol or maybe something slightly stronger is all that's needed for the first day or two. Really, within a few days, patients are back to normal life. And we do. I mean, because I do predominantly adults, I don't do paediatric cochlear implantation surgery. A lot of our patients are, you know, in their 80s 90s and they tolerate their surgery quite well.

Dr Paul Varley: It's certainly not like having a [00:17:00] major thoracic or abdominal operation and the complications are very low. The only one we really get of any significance, and it's still not very significant, is post op,  operative infection, which as you know can happen with any implant in the body. Our infection rates at SA cochlear implant centre ( SACIC) are well below 1%.

Dr Paul Varley: There is a risk of injury to the facial nerve, but we've had no cases of facial nerve injury in the 20 odd years that I've been doing them. Patients are occasionally a little dizzy for a few days, it generally resolves. But yeah, the complication profile is fairly minor really. 

Dr Gavin Nimon: Excellent. I suppose for the paediatric age group, obviously, if they haven't developed a good hearing ability initially, having one of these in, they can then interpret the cochlear implant as a way of actual normal hearing.

Dr Gavin Nimon: And I presume people who've got acquired hearing loss obviously helps them re establish it. But what happens to the people in the middle and the ones of congenital hearing loss, but then in their 30s, look at a cochlear implant. Has it got any role in that scenario as well? 

Dr Paul Varley: Yeah, it's a difficult area. We, Divide hearing losses, I guess, in pre lingual and post lingual.

Dr Paul Varley: So, kids that have lost their hearing, either born without it or [00:18:00] lost it very early on, before they develop speech, we're very keen to get cochlear implants in as soon as possible to allow proper development of their neural pathways. So, All the studies show that if you get cochlear implants in before 12 months of age in that population group, by the time they're at school at 5 or 6, their performance in the education system is identical to their kids in the class who don't have any hearing issues.

Dr Paul Varley: So, there's been a big push over the last 10 or 20 years to have early detection of Prelingual hearing loss and early cochlear implantation. That obviously leaves a cohort of people who had prelingual hearing loss but, you know, missed that early window to be implanted. So is there a role for implantation there?

Dr Paul Varley: It can be quite useful for sound perception, environmental sounds. If people have developed speech, that can be beneficial, but really the key to it now, uh, Gav, is early diagnosis of the paediatric hearing loss and early implantation. 

Dr Gavin Nimon: How are these implants funded in Australia? And obviously, someone with private insurance, [00:19:00] I presume, is partially covered under that. But, uh, what about in the public system? Are these done in public as well? 

Dr Paul Varley: There's a public and a private program in South Australia, or Australia wide really. I can't speak too much about the paediatric programs, I've never been involved with that, but I think on average they do about 15 kids a year.

Dr Paul Varley: That's the rough number in South Australia of kids who are born or present with a severe hearing loss in that first year of life. So those numbers are fairly steady and those kids all get done through the children's. The adults Get done either publicly or privately. They get publicly, they're done through Flinders Medical Center.

Dr Paul Varley: I did work in the public program up to about, or seven or eight years ago, I guess, public funding has improved in recent times, but there is a, I believe still a bit of a waiting list .In the private system, as long as you've got gold or silver, a level of hospital cover, they'll pay for the surgery and the, uh, implant itself, which includes both the internal and the external component.

Dr Paul Varley: I personally don't charge any gaps on the surgery, so really the, the hospital stay, the implant, the surgery will be covered by health insurance. There are some fees associated with what we call the switch on process. Generally speaking, I tell most of my potential recipients that they'll get out of it for probably less than they'd pay for a decent hearing aid

Dr Gavin Nimon: What about the longevity of the implant though? How long does that last for? Does that need to be changed over the, particularly the actual sensor? The cochlear implant itself? 

Dr Paul Varley: The internal component is fairly robust. I mean, the first one went in, in Adelaide in 1985 and that's still going. The cumulative failure rate over time of the internal component is under 1%.

Dr Paul Varley: So occasionally, like anything electronic, they may fail and they can be replaced, but that is obviously another operation, but fortunately that's extremely rare.  the external component, the speech processor tends to get upgraded and every four or six years it'll be upgraded with a new one. But the manufacturers make the new external speech processes backwardly compatible with the cochlear implants.

Dr Paul Varley: So, if you had a previous generation cochlear implant, the internal component will still work with the new generation speech processor. So you don't have to change the internal component unless it fails. 

Dr Gavin Nimon: And what about firmware upgrades to the external processing unit? Is that something that's done regularly?

Dr Paul Varley: There's a lot of work going on with them all the time Gav, and so a lot of work done on the speech processing algorithms and each new generation is better at, at breaking down the speech sounds and, and making them clearer. There's also directional microphones, they'll talk to each other, uh, streaming devices from televisions and iPhones and a, a range of what's called assisted listening devices.

Dr Paul Varley: So. Like all things, you know, every iPhone is better than the last one and the speech processes are the same. So the patients can get the benefit of the newer technology without having to change their internal component, which is great. 

Dr Gavin Nimon: And what advice would you give the younger generation to prevent going down this pathway of needing a cochlear implant?

Dr Gavin Nimon: Is there anything they can do to look after their hearing at all?

Dr Paul Varley: Well, really, just look after your ears with noise exposure, Gav, would be the main thing. A lot of the other causes are going to happen regardless of what you do, but there are obviously concerns with the younger [00:22:00] generation and the amount of noise exposure with the earphones and things that are very common these days, and we do worry about the amount of noise exposure the younger generation are getting, and I guess time will tell what sort of effect that has.

Dr Gavin Nimon: And are there any contraindications to having a cochlear implant, Paul, such as dementia or any other neurological disorders?

Dr Paul Varley: Um, I guess the main contraindication would be if somebody wasn't fit for surgery for any reason, but that's extremely rare these days. And as we discussed before, it's a relatively minor operation from the point of view of your physiology.

Dr Paul Varley: We used to think that early stages of dementia or dementia were contraindications to doing a Cochlear implant because it was thought that people may not be able to learn. to interpret the sound, but there's been a lot of work done on hearing loss and dementia in the last decade or so, probably longer now.

Dr Paul Varley: And all the studies suggest that it’s one of the few interventions that we can do that has an effect on cognitive decline is to maintain hearing. And it kind of makes sense when you think about it, but if you have less auditory stimulation and interaction with the world around you, it kind of makes [00:23:00] sense that that may have an impact on your cognitive decline.

Dr Paul Varley: So, Rather than being a contraindication now, uh, we think with early onset of cognitive decline, if there's an associated hearing loss, we should do as much as we can to rehabilitate that, whether it's hearing aids, other forms of surgery or cochlear implantation. So that's changed certainly quite a bit in the last decade or two.

Dr Gavin Nimon: And is it the case that you either use one hearing aid or go for a cochlear implant, or can you use both together? 

Dr Paul Varley: No, absolutely. Using both is, is beneficial. There's this concept of bimodal hearing. So you have the electronic hearing from the cochlear implant, and acoustic hearing from your natural hearing.

Dr Paul Varley: And they give you different things. So the acoustic hearing is often better for low frequency sounds, and the cochlear implant is good for mid to high frequency sounds. So we've developed over time this concept of bimodal hearing and marrying those two sounds together. And that can be done either one ear having a hearing aid or normal hearing and the other ear [00:24:00] having a cochlear implant.

Dr Paul Varley: In fact, sometimes we put cochlear implants in people with profound hearing loss in one ear and normal hearing aid in the other. And it was thought for a while that those two different sound types might confuse each other and lead to a poorer hearing out. Um, but it's been shown quite clearly that that doesn't happen and the two types of hearing will merge, if you like, over time.

Dr Paul Varley: And people who have a combination of acoustic hearing and electrical hearing will do much better than one or other alone in that, in that scenario. So it started off with the concept of, well, a cochlear implant in one ear and an acoustic hearing aid or normal hearing in the other. And then it was thought, well, Some of the people we're implanting actually have reasonable residual hearing in the ear that we're going to put the implant in.

Dr Paul Varley: So, if that can be preserved, then we can have bimodal hearing in the one ear. So you can put a cochlear implant in to restore, say, the mid to high frequencies and maintain the low frequencies which they can still use. And [00:25:00] if you can do that Then, the overall performance with hearing over time is much better.

Dr Paul Varley: So a lot of work has been done at the moment on hearing preservation techniques and a lot of cases now we can put a cochlear implant in an ear that has some residual hearing and preserve it so essentially the patient gets both, uh, hearing options. 

Dr Gavin Nimon: Brilliant. A thought that comes to mind actually is, what if I'm an older person who enjoys my classical music and going to listening to quartets?

Dr Gavin Nimon: And my hearing goes off. Will a cochlear implant actually improve my ability to hear that or is it only purely for listening to voices? 

Dr Paul Varley: Music is one of the areas where there's a lot of work being done and I never tell people that it's a device for music appreciation, I don't call it that, it's a speech perception device.

Dr Paul Varley: They have said a some of our recipients enjoy music. Some report that they don't and it's discordant. So I guess if you enjoy music with your cochlear implant, I would consider that a bonus. That said, again, with all the research and progress that's being [00:26:00] made, music appreciation, I'm sure will improve over time.

Dr Paul Varley: But the other thing I tell people is, well, look, you've got reasonable hearing, and say we're doing it for someone with reasonable hearing in their other ear. If the cochlear implant is interfering with that music appreciation, just turn it off and use your other ear for your music. So it doesn't necessarily interfere with music if you have that option to turn it off and just use your natural acoustic hearing that you still have.

Dr Paul Varley: But yeah, short answer, Gav, is I would never tell a patient that they will have fabulous music appreciation with a cochlear implant. 

Dr Gavin Nimon: Okay, further question is prior to surgery, are there any investigations to just double check the anatomy such as CT scan or anything? Uh, 

Dr Paul Varley: yeah, we do a CT scan routinely as part of the workup, sometimes an MRI scan, but I generally just do a CT scan to look at the anatomy of the cochlea and the mastoid and middle ear region.

Dr Paul Varley: Excellent. 

Dr Gavin Nimon: Look, how often are these procedures actually undertaken? I mean, how many would be undertaken in South Australia each year, for instance? 

Dr Paul Varley: I would guess probably between the public and private programs around 120 to 130 adults and probably [00:27:00] 15 kids will get cochlear implants in South Australia.

Dr Paul Varley: What we do know is that there's way more that would benefit. Uh, we're probably just scratching the tip of the iceberg as far as people who would benefit from a cochlear implant. So it's about increasing awareness. of the technology, what it can offer, and encouraging people if they are struggling with their hearing and their hearing aids to at least consider that as an option.

Dr Paul Varley: And we're always more than happy to see people at the Cochlear Implant Centre to do that initial assessment. And people say, when should I think about having a cochlear implant assessment? I think, well, basically there's no absolute level with your hearing. It's when you've got hearing aids, you've got good hearing aids that are well fitted and you're still struggling to understand your family.

Dr Paul Varley: or your colleagues, that's the time to have an assessment. And the numbers are increasing over time, but we're still really just scratching the surface. 

Dr Gavin Nimon: And with hip surgery and knee surgery, it takes a little while to get used to walking and obviously need a lot of physiotherapy, etc. After a cochlear implant, do you need any rehab for it?

Dr Gavin Nimon: Is anyone involved in the process or does it almost instantaneous? How quickly does it take someone to [00:28:00] get used to actually perceiving the sound after that?

Dr Paul Varley: Yeah look, it's not instantaneous and there is a program we call switching on and mapping. So after the implant's done, a couple of weeks after that, they'll go back to the cochlear implant centre and we'll start the switch on process which is anywhere from five to seven appointments over the course of the first month, each of about an hour or so.

Dr Paul Varley: And the audiologists need to adjust the electrode stimulation levels essentially to give the patients comfortable hearing and good speech perception. And that's a highly skilled specialty in itself, cochlear implant audiology, and I don't pretend to be an expert on that, but it's, uh, it is reasonably intensive for the first few weeks.

Dr Paul Varley: Patients can find it quite tiring and a little bit emotional as they're having good days and bad days, but usually fairly quickly over the first month or two, they'll start to get good hearing. Some patients take longer. I've had, I've had people who've had their implant and I've seen them at the end of their switch on and they love it.

Dr Paul Varley: They're getting fantastic results from it. I've [00:29:00] had other people, it might take them six or 12 months to get the good result. The interesting one is the people with residual hearing that we preserve or they've got bimodal hearing, they're using the two types of hearing. It can take a little longer for the auditory pathways to adjust and merge properly.

Dr Paul Varley: But interestingly, the sound can pitch, shift and adjust over time. So it sounds more natural as well. So It's not like a pair of glasses that you put on and you're away. There is a bit of work involved both for us and the recipient in those first few months.

Dr Gavin Nimon: Now final question, and I doubt there's much research on this, but obviously COVID does affect neurology and has affected sensations and how people perceive sensory perception.

Dr Gavin Nimon: Has it caused an increase in the amount of neurosensory hearing loss at all? 

Dr Paul Varley: I don't think anyone knows. I certainly see a number of people who've had COVID who present with auditory symptoms such as tinnitus or, or hearing loss. Is it occurring at an increased rate that it occurred before? I don't know.

Dr Paul Varley: Um, and I don't think anybody knows yet. I think that will come out over [00:30:00] time. Certainly there are viruses and respiratory viruses that can be associated with sensual hearing loss, including sudden hearing losses, but I don't think we've got the answer on COVID yet, Gavin.

Dr Gavin Nimon: Well, that's just brilliant. Thank you very much, Paul, for coming on Aussie Med Ed.

Dr Gavin Nimon: It's been great hearing about cochlear implants and this amazing implant and how hearing can be improved or even corrected. It's been great having you here. Thanks again. Dr. Paul Varley. 

Dr Paul Varley: Really enjoyed it. Thanks for asking me. 

Dr Gavin Nimon: No worries. Thanks a lot. I'd like to thank you very much for listening to our podcast.

Dr Gavin Nimon: I'd like to remind you that the information provided today is just for general medical advice and does not pertain to one particular medical condition or one way of treating a particular condition. If you have any concerns about information raised today, please do not hesitate to contact your General Practitioner for further information.

Dr Gavin Nimon: We hope you've enjoyed the podcast and please don't hesitate to give us a like or tell your friends about it or give us a positive review. We look forward to presenting another podcast to you in the near future on a different topic. Until then, stay safe. Thank you very much.[00:31:00]