Hearing Loss- Evlauation & Treatment 6/17/15

good afternoon and welcome back to Grand Rounds please remember to sign the attendance record at the back of the auditorium and also please remember to fill out the program of evaluations and if you could give us any ideas that you might have in regards to future topics or future speakers we would appreciate that today I have the pleasure of introducing dr. Marlin Hansen dr. Hansen is a professor in the department's of both Otolaryngology and neurosurgery at the University of Iowa he sits on the editorial review boards of several peer-reviewed journals he also has been very very extensively published in the literature particularly in regards to anti surgery and hearing loss and the CME committees quite pleased that he was able to join us here today to update us on hearing loss evaluation and treatment please join me welcome dr.

Hansen thanks oh yeah the mics working so it's great to be here and hopefully please make it interactive raise your hand you know jump up and down if you have questions during the middle of it we don't have to just go through this slide by slide but again I'm grateful for this opportunity maybe I thought to just start I just kind of remind you what we're dealing with here the inner ear well we you're all familiar with the external ear ear canal tympanic membrane language skin can have Skin Diseases and then the sound strikes the eardrum and then is transmitted through three small bones known as the ossicles which then move the fluid in the inner ear the inner ear is actually comprised of six sensory organs there's five they have to do with vestibular senses and then one that has to do with with perception of sound which is the cochlea and it's curled up like a snail so today we'll just focus on the cochlea and exclude all of the vestibular organs it's interesting to see that actually the stay peaceful plate which is what transmits the sound into the inner ear doesn't actually interact directly with the cochlea with the cochlear fluids but with the fluid that's in the vestibule all the receiver system but that gets transmitted into the cochlea one of the problems that the ear faces is this the fact that sound has very very very low energy so sound is just movement of air molecules it's a very low energy system compared to the visual system we have photons which are high-energy sort of things that you're detecting with sound you're taking very small energy movement of air molecules and yet you have to somehow get that energy able to move water molecules because it's the water the fluids in the inner ear that that have to move and vibrate in order to protect the sound and so the middle ear is sort of the mechanism that does that and we call it impedance matching so there's an impedance mismatch between air and water when sound comes from air and strikes water it's effectively extremely dampened and somehow you have to overcome that dampening that impedance of the water to be able to move those water molecules and perhaps at least when I talked to residents and to medical students they feel like the what are what they're taught predominantly is a middle ear the ossicles the bones in the middle ear work as a lever to amplify sound and that's actually a very small component it does help so the lever mechanism of the middle ear does help in overcoming that and if you lose that lever mechanism you have a slight reduction in how much the sound is going to be amplified but we can do processes and things that don't take advantage of the lever mechanism and yet they work quite effectively the real significant way that the ear overcomes impedance mismatch is that there's a an area difference in the size of the eardrum compared to the oval window where the sounds going to be transmitted so you can think of this this eardrum is a big collector of sounds and then it folk then the that hearing bones focus it down into the area of the footplate and there's a eighteen to one racial difference in the area of the eardrum to the footplate where it's focusing so that's like taking a woman say a 98-pound little petite woman in high-heeled shoes if she stepped on you that would generate much more pressure for the amount of force for the amount of weight that she has compared to if you had a 250 pound man step on you and his steel toe boots but that weight gets distributed over a large area and so it's it's the same concept of a nail right you focus the you take a point and then you're able to focus your energy into a very small area and then you're able to do that and so that's that idea of having a large area of the tympanic membrane that collects sounds and then focuses in to the foot plate is is important for the function of the middle ear in overcoming this impedance mismatch one other thing that just remind you that I suspect most of you are familiar with is that the cochlea the inner ear the basilar membrane is sort of the sensory organ where the where the sensory cells the hair cells sit on this organ or on this tissue and it has mechanical properties such that when sound comes into the ear high frequency sounds best vibrate the base of the cochlea which is kind of narrow and stiff and low frequency sounds best vibrate the apex or the top of the cochlea where the membrane is kind of wide and floppy and so you get this idea of this traveling wave in fact the the the only Nobel Prize awarded in auditory neuroscience has been for von bekesy x' work and this idea that that when sound comes in you get this this envelope of sound and if it's a low frequency sound that gets shifted towards the apex so this would represent the movement of the basilar membrane to a 250 Hertz tone and as you get higher and higher pitch sounds that gets closer and closer to the base and so you have what's called the tonotopic map of the cochlea that's one of the ways that your ear sorts out what frequencies of sound your you're hearing is we're along this basilar membrane do the cells get activated and so this is sort of again depicting that if you have 200 Hertz sound it's going to be shifted towards the apex and you get into you know a kilohertz sound or something like that and he'll be shifted towards a base one of the things that happened when they first did this work when von bekesy did this work he did it in in dead cats and though he got at this broad envelope that wasn't didn't have as much sensitivity as what they knew our hearing was cyclically and was broad more broadly tuned than what our hearing is so there was this concept generated that somehow within the cochlea there had to be something else happening an amplifier within the cochlea to further refine and amplify the sound that's coming in and it gotten it got known as a cochlear amplifier so again in a in a in a dead animal you would notice that you have this very broadly tuned sort of envelope with a traveling wave over the sound but then when they repeated it in a live animal you get a much sharper sound a much sharper tuning of that curve and it's amplified considerably and so this was known as a cochlear amplifier for a long time no one understood what it was what was happening in the ear that was allowing for this extra this extra activity or extra energy to be put into the system and was also tuning things and it wasn't until a few decades ago that they found that outer hair cells have this capacity that when they're depolarized somewhat like a muscle cell different different biomechanic way that they do it but just like a muscle cell when it's depolarized will expand and contract an outer hair cell can do the same thing and once that was discovered then they were able to sort of understand that when you put sound into an ear and you activate the outer hair cells they will capture that energy and then amplify it and that can be sent back out through the system so you have sound coming in and that sound gets amplified by the outer hair cells and can be transmitted back out through the tympanic membrane is now working as a speaker and so you have this odo acoustic emissions the sound is am it or the ear is emitting the sound in response to the sound that you put into it and that's Auto acoustic emissions and that's the clinical test that's used every day in newborn nurseries to test to see if whether newborns quote-unquote hear it's important to understand that otoacoustic emissions don't tell you that they hear they tell you that the outer hair cells are working so just to sort of convince you that the outer hair cells have this electromotility function this is a video and what's happened in this video if someone's put a pipette on the cell to change its membrane potential and they think it was sound so you see this outer membrane of the hair cell sort of having this motility and it's that that function of the outer hair cells is what a otoacoustic emission test is testing to see if this is occurring in response to sound now you believe me okay so and we'll come back to Otto acoustic emissions in just a minute so someone comes in complains of hearing loss and there's a lot of different things that could happen a lot of history you need to know is a sudden is it gradual is it one ears at both ears what's the Associated things all the typical things that you would do for for any sort of history of a medical illness just to remind you that tuning forks can be very helpful especially for people with a sudden hearing loss I strongly encourage you to try and do it the one thing I'll say about tuning forks is the one that you got kind of when you were a brand new medical student they were giving you your white coat and your reflex hammer and all those things they've probably had you get a tuning fork which is 200 and 128 Hertz that's not a tuning fork for hearing that's something you can use to test proprioception and if you test it that's what the patient's going to do is mostly get proprioception you can hear it but it's not a very good functional test that we use for these type of real tuning fork tests the ideal one would be a 512 Hertz tuning fork 256 would be okay but if you go down to 128 Hertz it's not very good so there's two tests that are typically done the Webber test is where you put the tuning fork in the middle of the head somewhere if they're really how hard of hearing you can put down their teeth on their incisors so you can put down their nose bridge just anywhere in the head and you ask them this is what you do when someone has better hearing in one ear than the other and you're trying to sort out is it a conductive loss in that ear or is a sensorineural loss if they say I don't hear very well in my right ear and you put the tuning fork in the middle of their head and they hear it in the right ear that implies they have a conductive hearing loss in the right ear if they say I don't hear very well on the right ear and you put the tuning fork in the middle of the head and they hear it in the left ear that would imply they have a sensory neural hearing loss and then there Rin RNA test can can sort of confirm those things it's where you're testing the function of bone conduction versus air conduction so you put the tuning fork on the mastoid portion back here and and then you put it in front of the ear and you ask them whether it's loud or behind or in front and if it's a lot of on the bone and that implies that the inner ear is working normally but the conduction mechanism isn't so it would imply a conductive hearing loss and if they hear it louder in front of the ear as opposed to on the bone that implies a conduction mechanism is normal that the middle ear is working and so they should hear it better in front and that would imply they have a sensory neural hearing loss but tuning forks are or even in the best of hands someone you know I see lots of patients every week who have hearing loss and even in my hands are not exquisitely helpful they are helpful in certain things but I don't make diagnoses just off tuning fork exams so I can't emphasize enough the importance of if someone has a hearing loss get a hearing test I mean you know if someone had other things you'd test it and so just get a hearing test it'll save you lots and lots and lots of trouble and hearing tests are actually a battery of tests it's not one specific test that they do and they're all subjective they all require that the patient is has a mental capacity that they can respond and understand what they're being asked to do and that they have a willingness to participate so if you get someone who was assaulted and they are suing someone or it's a police officer who's trying to get workman's comp and they're claiming that they have a hearing loss in one year if they're not willing to participate in that they can fake or they can not respond to the sound in the ear and they could be giving you a false report on a hearing test so that requires that they're honest and that they're able to do the test and we do pure-tone audiometry that means specific tones like a 200 Hertz a 250 Hertz tone a 500 Hertz tone a thousand Hertz tone that 3000 Hertz tone whatever you give us a very as tone and they do it two ways they either do it by putting an insert or a headphone over the ear so you're going through the ear canal and through the eardrum and that's air conduction and then they also test how it does on bone so they'll put an oscillator back on the bone and send the send the sound in through the bone so that you're bypassing the middle ear and you're testing bone conduction it's also important to understand was speech so they do what's called a speech reception threshold and then a speech discrimination score wait and I'll get into that in just a minute so again pure tones presented at different intensity so they do a two hundred and fifty Hertz tone and then they see how soft the sound can be oh yes please yes so the question is for every if case people didn't hear as I understand the question I'll repeat it if someone is malingering can you use some of these objective tests to verify so like an auto acoustic emissions and the answer is yes that's a great use of them there's actually ways that if they're faking it in one year there's audiological techniques that a good audiologist can actually ferret it out there's psycho acoustical things that they can do it's called the Stingers test that they can actually ferret it out but even so it's nice to confirm it with an objective test and in that case Auto acoustic emissions and I'll talk about later even better an auditory brainstem response radar will tell you whether or not their ear responds to sound so yeah that's a good so again the the the threshold is determined by where that patient can first can get just detect the sound 50% of time they're responding yeah here at yaw here that's their threshold of hearing and it's calibrated to what normal young adults here so everybody's hearing loss is presented our hearing level it's presented sort of flat according to a normalized population our hearing is not flat we hear certain sounds better than others but it looks flat on the hearing test because it's normalized this is just some examples of common intensities of sound in terms of hearing levels so you know a whisper would be about 20 decibels so anywhere between 0 to 20 s consider normal hearing most people speak at about 60 remember it's a logarithmic scale so things can get quite the intensity of sound goes up tremendously as you go into higher things so a hundred decibel sound is 10 orders of magnitude louder than the zero decibel sound and so again how do you read an audiogram this is the intensity of the sound going down this way your loudness this is the frequency of sound going across this way and this is testing in both ears so in in this instance both the right which the red and the left which is a blue ears the patient could hear the sound at 25 decibels at 250 Hertz and then at 4000 Hertz and the left ear they heard it at 40 and in the right ear at 45 and we'll skip that so so normal hearing is considered anything less than 25 decibels so we give them a range of 0 to 25 to be considered normal hearing so in this person both ears have normal hearings up to about 2,000 Hertz and then as they get into the high frequencies they start to lose a little bit of hearing that's typical of someone with presbycusis speech frequencies are usually around somewhere between 500 and 3,000 so the critical critical areas for hearing their 500 to 3,000 so then in addition to doing the sound through the ear canals they also will test it by putting the putting it through the bone and that's important because the bone directly tests the inner ear function it bypasses you could have you could have your ear can you could be born without an ear canal and as long as your inner ear is normal you'll hear normally through bone conduction so the important thing to remember is bone conduction tells you what the inner ear function is an air conduction tells you what the overall system is doing so if someone has a difference between their bone conduction and their air conduction what's called an air-bone gap that tells you that the middle ear or the eardrum or the ear canal is not working and that tells you there's a conductive hearing loss so air-bone gap is a conductive hearing loss because there's a difference between what the inner ear is capable of doing and what how the ear is actually functioning when you put sound in through the ear canal so now we'll talk about these speech scores so there's you'll see this common in the hearing test pure tone average which is just an average of these frequencies across here a speech reception threshold which is where they can first start to understand speech so that's more critical than pure tones so pure tones tell you where they hear specific tones but no one really cares where they hear a thousand Hertz tone they care where they hear someone's voice and that's what this speech reception threshold tells you is the same thing as you get for a pure tone except at speech that's being delivered not not a specific tone and so this this is this should be this should actually be very close the speech reception threshold should very closely kind of mimic the average of the frequencies across the speech spectrum so if you look at the average across here the speech reception threshold will be very close to that or something fishy's going on and then there's this probably the most critical thing that happens and people don't pay much attention to it is a word recognition score so to get the word recognition score what they do is they look at a patient's speech reception threshold and they say okay they can hear speech at 40 decibels and then they'll turn it up the sound 40 decibels more than that so 80 decibels and then they ask them to repeat the words that are being spoken so they'll say you will say ball and if they say ball they get it right and if they say wall or fall or smaller doll they miss it and you will say sidewalk and if they say sidewalk they get it and if they say something else they miss it and so you're asking that when sounds are loud enough that they can hear them how well does their ear discriminate and that's the main problem that people have with sensory neural hearing loss is not just that they can't hear sounds that they can't discriminate sounds and so speech recognition or speech understanding or word recognition scores as perhaps the most critical measure of inner ear function that we have so these are just some examples and you can kind of look at them and I'll describe them and in your own mind you can kind of figure out what might be going on so in this patient this is air conduction in the left ear or these X's so you can look at that and say does he have normal hearing or not normal hearing in the left ear and you can see that everything is less than 20 decibels in the left ear so you would say that's normal hearing in the left ear okay then you look at the right ear and you look at air conduction that's how they actually hear unless they're wearing a bone conduction hearing aid air conduction is how we all hear so air conduction in the right ear is in these open circles in the red so this patient has a high-frequency hearing loss right in the right ear and then you say is that hearing loss due to inner ear or middle ear and so now you want to look at the bone curve and say where does the bone line where it's the inner ear function so you look in here and this is the bone curve for the right ear and you can say well the inner the right ear has a loss of inner ear function so then you look and see if this matches up the right ears about 30 decibels which would be about the average of this over here so the SRT seems about right and then you notice that their ability to discriminate words is poor in the right ear than the left ear so all of that put together would suggest that he has a sensory neural hearing loss in the right ear right because the bone curve is down and the speech discrimination score is distorted so here's a different example again look at the left ear you have the X's which are the air conduction in the left ear and you can say that's normal hearing in the left ear you don't even need to do bone conduction because they hear normally then you look in the right ear and you can see that there's a moderate hearing loss across all frequencies this is air conduction in the right ear and so then you say well what's the inner ear function and in this case the bone curve is up here within the range of normal so the right inner ear is normal but the hearing is abnormal so that implies an air-bone gap so this is what an air-bone gap looks like so what kind of hearing loss would that be a conductive hearing loss right so this is a right conductive hearing loss and then maybe one more to go through so this could be a patient with a hole in the eardrum with an a sick Euler disruption otosclerosis or something like that so here's another hearing test this is a right ear air conduction and you can see that in the right ear there's a moderate hearing loss and in the left ear air conduction there's a more severe hearing loss so both ears have a hearing loss the hearing in the left is worse than the hearing in the right and then you look at bone conduction and they both are the same so bone conduction in the right ear is at about forty five forty fifty and air conduction the left ear is about 40-50 so the right ear has no air-bone gap has a sensory neural hearing loss and the left ear has a conductive hearing loss and a sensory neural hearing loss right because the the inner ear is not quite normal so this would be a right sensory neuron left and the left mixed hearing loss this could be someone with presbycusis that has a hole in the left eardrum would be an example of how you might get something like that that makes sense okay so back to this otoacoustic emissions again this is a major it's it's very rapid you can just do it in a newborn nursery you have a that child doesn't have to be sedated you can do it in your clay it can be done in in an audiologist clinic with it or with regular patients and again it's testing this outer hair cell function so you put a probe in the ear that delivers a sound and you have very sensitive microphone that detects the sound that's coming back out that's generated by the outer hair cells and if if that's not working either there's something wrong with the sound going in and coming out a conductive hearing loss or something or there's a problem with the outer hair cells it doesn't tell you that they hear it only tells you that up to the outer hair cells it's working but in the vast vast majority of cases if the outer hair cells are working then the rest of the system is going to work as well but it is possible to have a newborn who passes a newborn hearing screen and yet doesn't hear if they're born without an auditory nerve or some other things we call that auditory neuropathy so far if they pass their newborn hearing screening but they're not reaching their milestones developmental speech milestones and things like that or the parents have concerns it bears repeating it or getting a different type of test to confirm it because this only tests a system up to a point but it's a really easy way to do a test I mean it's done because it's so well and it'll get 99% of the cases anyway this is kind of the rapport you don't really need to look at that so the other thing you can do which is an objective test is called auditory brainstem response ABR some places they call it bear and this is where they put a EEG like electrodes across the scalp and then you deliver a sound to the ear and then the computer you deliver it many times thousand times bump up up up up up up up up deliver the sound and you get a lot of activity you get EMG activity get cortical activity but if you average it over a thousand you can average out all the responses that are not synchronized to the sound and then you get a series of potentials that represent the response of the auditory nerve and the lower brainstem to the sound that you're putting in by averaging across multiple month sweets and it sort of looks like this so you get these this was if a clicks put in there this is a tone or hurts put in you get better responses the broader the sound so click gives you a better response and you get these series of peaks and waves that sort of detect this would be early auditory nerve activity and then this is just in the cochlear nucleus at the brainstem and then as it moves up probably into lower brainstem auditory pathways and you're seeing those responses and so in this test you actually see the response of the auditory nerve and the lower brainstem so this is actually a better test for hearing than the otoacoustic emissions and it's an objective test but this does require a child to be sedated and it takes a lot longer so it's a more complicated sort of test but you can get a threshold you can see that as they monitor these responses this way five by ten decibels it all it goes away by five decibels you get a little bit of peak so then you get a threshold response to say about what their hearing level is the peak wave one here that is early auditory nerve so that's probably the the most distal part of the auditory nerve as it responds this wave to which is here is probably distal auditory nerve close to the brainstem nuclei this is probably cochlear nucleus just surface like EEG electrodes oh it's I several centimeters it's a long ways right yeah it's actually a series of electrodes so they have them on the mastoid on the other side they have some reference electrodes on the vertex in here so it's quite a ways away that's why you have to deliver it over so many times and the computer has to average his response the other use for this test is for instance pay people who have mental retardation or other things and it's also can be used to screen for retro cochlear pathology if you're concerned that someone may have an acoustic neuroma they'll actually have a delay and they're in these wave responses if there's a tumor pressing on the auditory nerve it's a fairly sensitive technique the second most sensitive technique for acoustic neuromas is an ABR the most sensitive is an MRI but an ABR is better than a cat scan for detecting acoustic neuromas the other thing that can be done is to look at middle ear function so there's this tympanometry so this you put a plug in the ear you deliver or you you very air pressure and then you deliver a sound and you look at how well that sound is sort of emitted off of the eardrum and it gives you a sense of the compliance of the eardrum and this is something that pediatricians often have in their offices to kind of confirm their Otis Otis copic views and you get this sort of this is the readout that you get it so here's the the variation of ear pressure in the ear canal and then this is the acoustic immittance or you can think of this as the compliance of the eardrum in a normal in a normal patient you should the eardrum should be most compliant when the ear pressure is the same on the outside of the ear is on the and the ear canal is behind the eardrum so you should have the most compliance when there's in a normal situation at zero and then as you increase the pressure in the ear canal forces the eardrum in and it becomes less compliant and as you reduce the pressure in the ear canal it pulls the eardrum out and it becomes less compliant so in a normal situation you should have a peak at about zero Pascal of pressure if someone has a fluid behind their eardrum then they don't get any compliance eardrum is stiff it doesn't move so you get this flat so this is a typical thing and this is how you distinguish it helps a pediatrician to distinguish fluid behind the eardrum and confirm what they're seeing so these are actually fairly easy tests that there's handheld devices you can do in your own office and then this would imply if you get sort of a peak down here it would imply negative middle ear pressure so someone who has some eustachian tube dysfunction there's no fluid behind the eardrum but their eardrum is retracted and as you reduce the pressure in the ear canal that pulls the eardrum back out into its natural position and then you start to see the peak so that's tympanometry so what are some other clues to conductive hearing loss conductive hearing loss because they hear their own sounds inside their head very well they actually can modulate their voice so people with conductive hearing loss hear their own voice quite well in fact they hear it better than normal if you guys plug your ear canals you can hear your voice well and it may even sound a little bit loud to you and so you may speak softly if you have a conductive hearing loss and but you'll modulate your voice you'll know if you're being too loud or too soft or whatever and people with conductive hearing loss hearing aids work great for conductive hearing loss because all you need is extra energy in the system if the energy gets into the ear the ear can interpret it it can discriminate it it can understand it and they just need louder sounds so common causes of conductive hearing loss you know serous effusions chronic otitis media with perforations or a sick euler erosions cholesteatoma otosclerosis and then trauma would be common things otice chlorosis may be a new concept for you it's actually common and these are people who sort of in their 20s to 40s sometimes a little older in life develop this very slowly gradual onset of hearing loss it runs in families and it's due to this sort of abnormal bone formation around the stay piece footplate so you can this is a histopathological slide showing that right at the front edge of that stay piece footplate you get this bony remodeling so this is the stay piece here this would be the cochlea this is where the sound would come in and that stay piece gets fixed it's typically in both ears but sometimes just in one ear it's a gradual progressive sort of thing and it's a very easy disease especially early on to treat so they can wear a hearing aid hearing aids again worked very well for conductive hearing losses or there's a surgical procedure where we can remove this fixed bone and replace it with a prosthesis that's known as a stapedectomy and that works very well ninety-five percent of time they're going to have back to near normal hearing in the ear there is a risk of hearing loss with a stapedectomy but it's quite low so sensory neural hearing loss is very common it's probably by far and away the most common sensory deficit that we have and I think the thing that people generally fail to recognize is how much difficulty it causes for the patient and their families it this becomes as a social socially it becomes very difficult and emotionally not only for them but for family members presbycusis is of course the most common you can think of as sort of a genetically determined progressive hearing loss that typically will affect the higher frequencies more than the low so you see this sort of classic pattern where you have pretty good low frequency hearing and then it's symmetric affects both ears the same both ears have the same genetics both ears have the same age so hearing should be symmetric hearing loss and it's this down sloping and it how they do on speech discrimination scores is variable some people do quite well and some people don't and that really has an impact on how they're gonna do with hearing aids if they have poor discrimination scores they're not going to be good hearing aid users noise induced hearing loss is was very common early in the industrial revolution then OSHA standards came in and it's been mitigated somewhat but OSHA standards don't apply to farmers in Iowa or other people you know independent contractors that are doing construction work or something like that and that they certainly don't apply to iPod users which is we're really concerned that there's a rising generation that's going to have quite a bit of hearing loss because the noise exposure you get when you're 20 may not manifest until you're 45 or 60 but the damage could have been done in the 20s and it has a very classic recognizable pattern on a hearing test so they always have this loss no matter what the frequency of sound that they were exposed to the damage is always most most evident or greatest at 4,000 Hertz and so you see this knotch remember presbycusis you see this sort of fall-off and then it the higher the frequency the worst of hearing you don't get this recovery in the highest tones but with noise induced hearing loss you get this notch at 4,000 Hertz it clearly begins to involve the higher frequencies but you have a notch to the pattern and then it just progresses over time and they they have a lot of trouble with word recognition scores people who have noise induced hearing loss genetic there's lots and lots of genetic causes they can be syndromic non syndromic there's at least a hundred different genetic causes and they can have early onset congenital they can have sort of progressive patterns that manifest in childhood in adulthood or other things so it's hard to go through all the different causes for genetic hearing loss aminoglycosides probably the thing I would drive home here is for those of you that use gentamicin screening the hearing is not the best is not the hearing the the cochlea the hair cells in the cochlea are much more resistant to gentamicin than the vestibular hair cells if you're giving someone systemic gentamicin there's a much higher risk of a bleeding their vestibular system than their cochlea so most people sort of will ask and inquire and maybe even do Oh AES to test to see how the hair cells are the cochlear hair cells are handli not but I see several patients a year who are vestibular cripples and yet have pretty good even normal hearing after having systemic gentamicin so that's just one thing to remember is gentamicin is much more toxic to the vestibular organs than it is to the auditory organs in fact we use that to treat many years disease where we're trying to save their hearing but oblate one vestibular system the other one to be aware of where we sometimes see things get missed as a sudden sensory neurone loss I would say 8 out of 10 patients who have a sudden sensor in her hearing loss something like this happened they went to the they notice that they weren't hearing suddenly in one year they say I can't hear in this year they go to the ER urgent care they get looked at they get told they have fluid behind their eardrum and they get put on antibiotics and about a week later they report to their general practitioner and they say you know I have this fluid behind the eardrum I was seen in the ER they gave me this antibiotic I still have a hearing loss and they say well it must be resistant so they give you a different antibiotic and it's about a month before they ever get a hearing test and and the the problem is sudden sensorineural hearing loss if it's the if it's caught early you can treat it and treatment is about 60 70 percent effective if you can give them steroids within that first week or even two but often by the time we see it it's been missed and it hasn't been treated other than with antibiotics the treatment for it is steroids antivirals are often given but don't have a proven efficacy but but high-dose steroids are effective if they're given within the first couple of weeks and sometimes we'll inject the steroids in addition to oral ones or if they're diabetic we can inject the steroids and those also work well about 1 percent of people who have asymmetric auditory function will have a vestibular schwannoma electrical clearly j'en so anyone with asymmetric auditory function either isometric tinnitus unilateral tinnitus only in one year or hearing loss sensory neural hearing loss only in one year should have some sort of workup typically an MRI to look for a retro cochlear lesion to see why they do it it's usually it'll come up negative but the first symptom of all vestibular schwannomas the vast majority of 70% of patients are first symptom is unilateral tinnitus and then their second symptom is hearing loss they do they are not dizzy even though it's off the vestibular nerve very few of them are dizzy until they get quite big and then maybe one other disease with sensory neural hearing loss that's asymmetric that just to briefly highlight Meniere's disease and hearing loss is always present so if someone has vertigo recurrent episodes of vertigo and they don't have a unilateral hearing loss they probably don't have Meniere's disease they might have migraines or they might have something else going on they probably don't have many years disease Meniere's disease is way over diagnosed so to diagnose Meniere's disease you definitely need to have an audiogram that shows that they have a hearing loss they have a very classic hearing loss it's different than most it's in the low frequencies and it fluctuates so one day it's bad the next day it's good it sort of fluctuates over time and so you see this sort of pattern like this in addition to that in addition to the hearing loss they'll have fullness pressure roaring in the ear and the severe recurrent attacks of vertigo and and those become the dominant the vertigo attacks are much most of them will say I've easily give up my hearing if I could get rid of my vertigo attacks so then that sort of will just quickly go into ways that we can treat so this is a this is very common right I mean I my dad has a pretty bad hearing loss and he's had three sets of hearing aids and they all end up in the sock drawer and it's because of this problem especially in noisy situations a patient with sensory neural hearing loss does fine one-on-one their problems is when there's lots of people talking the understand and you put hearing aids on them and then hearing its amplify all the sounds and so they're still left with this dilemma of being able to understand what they want to hear and technology's gotten a lot better I'm not saying hearing aids aren't appropriate there are great treatment for mild and moderate cases of sensory neural hearing loss and great treatments for conductive hearing loss but even so they're not perfect their hearing aids not hearing cures because often there's this dilemma of speech discrimination and at some point hearing aids become where they really can't do any good you can it's like having a radio that's out of tune and all the hearing aid is doing is cranking up the volume on the radio you need tuning in the ear and that's what the cochlear implant does so cochlear implants are used for people who have severe to profound sensorineural hearing loss where they can't really get the benefit from the hearing aids and it's a series of electrodes placed into the ear that then delivers the the process sound vien electrical pulses to the auditory nerve in the ear and I thought I'd just let you hear what that might sound like so this is one of our areas of very active research is how we can increase the number of channels in a cochlear implant so this is simulation of what it would sound like to a cochlear implant patient if they only had one channel the first cochlear implant was single channel so this is a car this is a sentence and when you can understand that raise your hand anyone get it what did you get what was it husband okay eight channels this is what typical cochlear implant users are between eight and sixteen channels why was it okay we'll see if you're right the wife helped her husband okay so the wife helped her husband and you can see for speech actually the implant does quite well people can be perfect I mean you can have a child who's born profoundly deaf and they have normal speech development and very close to normal speech understanding and quiet but they don't do good noise and they don't do well with music so here's another here's an example of 13 channels no cochlear implant patient I mean 32 channels no cochlear implant patient has 32 channels but this would be music simulated through 32 channels this is what it should sound like so there's a big discrepancy of how we're able to deliver and understand speech as compared to a comp or complex things like music or speech and background noise with a cochlear implant one of the things that have if if this was a hearing test one of the things that we've recently been working on particularly at Iowa but now it's actually FDA approved as of last year is this concept of someone who still has this is a range of their hearing so they have no hearing in these high frequencies and yet they have some preservable useful low frequency hearing and the idea is to do hybrids just like a hybrid vehicle is sort of gas and electric so we do acoustic and electric so we use a small electrode to fill in for these high frequencies and then they wear hearing aid for the low frequencies so they're using both acoustic and electrical and a cochlear implant in the same ear and they do really well these are the best of the best cochlear implant users so I thought to close would just do one quick case presentation and have you guys think about it a little bit so this is a 40 year old police officer and he was hit on the right side this was this is an actual case I had so he was hit on the right side of his head when he was trying to arrest someone and he complains of hearing loss in that year and on exam his his eardrum looks normal he doesn't if you if you put the Weber in he goes to the left ear and he can't hear anything no matter how you put it on the right ear whether it's bone or the air and this is his hearing test so in his left ear he has normal hearing this is where he's telling you you he hears in the right ear and then bone conduction they can't do it any louder than 60 decibels it starts to transfer to the other sound so this is responding is like it's a dead year his word recognition score his pure tone average though is would be a 90 but he but he's starting to say he can hear speech at 55 and actually if you give words to that there he responded he gets 68 percent of them right so this is a bit of a red flag to red flag for several reasons they should always be able to hear the tuning fork no matter where you put it on their head right if you put it on this side it's the same as putting it in the middle he should have if his right ear were dead he'd still hear it in the left ear right even if you put it here if the sound doesn't matter where you put it on the skull so that's a red flag that when you put the tuning fork by the ear that he doesn't respond he's just not responding at all he's also given you these really elevated thresholds but his SRT is quite low there's no way that he could under speech and understand 68% of the words if as his hearing was this profound of a loss so it's kind of a red flag that that he may have some some game issues and looking for disability or things like that so what might you do in this case and we're sort of highlighted it by the question before yeah so look for some evoked responses so odor acoustic emissions was actually present in both ears so if we put the probe in his ear and look to see if things were working that was it was do it and then when we did a brainstem response he had responses down to normal hearing levels so we knew at that point that he was feigning a hearing loss and that it was functional okay so hopefully that was helpful to you and thank you very much if you have questions I'm happy to take him yes so if if they're doing speech scores and it and it's the what about the the audiologist who's delivering it yeah so there's two ways they they have taped they have taped lists that they can use so they can use a tape list or they can use their own voice where they say it and and so as long as they're a native English speaker either one of those is fine actually patients do better with live voice than tape voice but but if it's a non-native English speaker so if if they're doing their live voice it still goes through an audiometry that controls the intensity or the loudness of the word that's being given to them it it it probably does a little bit because if they have a high high frequency hearing loss they're gonna do better with male voices the tape voices are generally male but but people tend to do better with live voice than they do with tape voice so it minor differences I it's not doesn't come into the equation doesn't make a huge difference yes what's actually going on with it it can be episodic and sometimes it isn't it tends to be we don't know what causes tinnitus almost everybody who has tinnitus has damage to their auditory system but not everybody but most people the classic would be someone with a high frequency hearing loss and they get a high pitched in this and we don't know why that is perhaps one way that I explain it to patients although we don't know that this is actually true or not is it sort of like a phantom pain if you cut off your finger you know the nerves not connected to the to the nerve endings to the receptor cells any longer and so the brain kind of fills in the sensations that that are sort of phantom and so and that's essentially what tinnitus is is sort of a sound that is perceived by the brain that's not generated somewhere else and it typically occurs when there's damage to the inner ear and so you could imagine at least for a patient it's easy to understand that their brain is kind of filling in where their ear is not being active and in fact if you have sound one of the most reliable treatments for tinnitus is just sound so they have white noise generators or fans at night and things because when their tinnitus is worse is usually when it's quiet so that's one of the reasons it might fluctuate is because the external noise is fluctuating or tinnitus can just fluctuate anyway just like pain or any other perception can Conflux wait the other thing I would say about tinnitus is interestingly cochlear implants are very effective in suppressing tinnitus not everybody but most people and again you're reactivating that nerve yury stimulate in a nerve that hasn't been stimulated for lack of input from the hair cells and so a cochlear implant reliably and 70 75 % of patients will suppress tinnitus so yeah it did difficult we it's it's a challenge yes actually that's that's a great question so I actually have a grant from the Department of Defense to do these hybrid cochlear implants in patients who and military people to see how well they do with it and we're having trouble recruiting because we had an age limit and the new people in the military don't have near as much hearing loss even those who are in Iraq and Afghanistan don't have near as much hearing loss as a World War two guys so they have it's not always a case the problem in the military is it's unpredictable when the noise you know you're walking along and all of a sudden ie D goes off but if it's a predictable thing you know you're going to go into a combat zone they they have your protection and things they do and there's actually very very active research in the military we also have a basic I'm a collaborator in a basic science grant looking at ways to reverse the damage done by noise and there are clinical trials underway to give antioxidants and some other drugs that are speculated to be auditory protective for people who they anticipate will be exposed to loud noises so they're doing things they're looking especially for drugs that can rescue not just prevent because again it's hard to predict you know you say well take your pill and then go shoot shoot someone that might be difficult because combats faradic right but if you had something that where they were exposed to the noise and then you could give it to them and rescue or regenerate then that would be better so there's actually a lot of quite a bit of funding available through the military they're working on it but they don't have a perfect solution yet okay thank you very much

You May Also Like