The third one here is a high peak and this one can be due to a couple of different things. Again, you see this peak falls outside of the box. Moderate levels are generally due to things like thinning of the tympanic membrane. So a child who has had recurrent infections may have thinning of the tympanic membrane and you may see moderate levels. The other thing, though, that can cause a very high peak is ossicular disarticulation and there you may see curves that literally go off the map. I guess I forgot to put the slide in, but there should be one where there is a completely flat line for the audiogram and this is one which I bet you will come up upon on the Boards. And there are two possibilities for explanation of when you have a flat line in the tympanometry test. One is that – and most commonly – it is a middle ear effusion so you have that fluid there and basically it’s pushing against that tympanic membrane and it just won’t move. The other possibility though is that you can have a perforation. So if you have a perforation in that tympanic membrane, when the pressure is put in it’s going to go right through that tympanic membrane and isn’t going to move it at all. So all you are going to see in a tympanometry test with a perforations is a very flat line. The key to the differentiation of these two is looking at the ear canal volume. And what you are going to see is, if there is a middle ear effusion, you are going to have an normal ear canal volume, 1 cc or so. Whereas if you have a perforation ear canal volume is going to go up and it’s going to be abnormal. Because what it’s seeing is this huge ear canal because that perforation makes it seem like the ear canal volume is going to be quite high. So you may see ear canal volumes of 3 cc or something like that. So that’s where the ear canal volume comes in and is very very important when you are trying to differentiate a perforation from a simple middle ear effusion.
Tympanic membrane images
Okay, on to audiologic evaluations. I think the trick here – I’m going to cheat, it’s really not cheating but – if you look at the tympanometry first I think it can suggest a little bit of where the pathology may lie. So here we have a curve that’s shifted to the left, which means negative pressure. Cialis professional online. The left ear is completely normal. And looking at the legend here, the air conduction on the right is circles, X is left ear and what you see here is essentially the air conduction is shifted down slightly. So this is just a right sided mild eustachian tube dysfunction with a retracted ear drum that’s just not going to function quite as well in terms of hearing. The second one, you see a flat line here. Most likely it’s going to be a middle ear effusion. I don’t think we have the ear canal volume. Let’s assume it’s normal. This time the X’s air conduction on the left side is shifted down slightly. So this is consistent with a middle ear effusion on the left side interfering with air conduction and on this one, and on the previous one, the brackets you’ll notice are for bone conduction. Those are completely normal. Remember that I said, with conductive hearing loss you are going to see abnormal air conduction, normal bone conduction. I hope this is getting through but you may have to review this afterwards later because it can be a little bit confusing.
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Finally, we have one where the tympanic membranes are completely normal on tympanometry. They move very nicely, the pressures are normal. But here you see profound hearing loss bilaterally on both sides and you see both air conduction loss and with the brackets you also see that bone conduction is abnormal and it is much worse at the higher threshold. So this is a fairly classic audiogram for sensorineural hearing loss.
Sep 18
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