Help with understanding ABR results

#1

Hi,
After reviewing my son’s ABR results, I am confused. Let me start of with a bit of history.
My son did his first ABR test at 2 months old and we were told he has severe to profound conductive hearing loss in his right ear. After researching online, I found it’s not possible to have conductive hearing loss in the severe to profound range so we went back to do a second ABR test. In the second test (same audiologist as first test), she then concluded that he has sensorineural hearing loss in the severe to profound range.
Due to the difference, I requested a third test by a different audiologist, the third test confirmed he has profound sensorineural hearing loss. However, I’m looking at the results from the third test and notice that his bone conduction hearing is better than air conduction by 30db which may mean he has mixed hearing loss. I’m confused at all the different test results. We were told heading aid would not help him because it’s in the profound range but if his bone conduction is around 55-60db, does that mean hearing aid could help him? His air conduction is 85-90db. Here’s a photo of his ABR from the third test.

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Thank you for the help in advance!

#2

Don’t take these as your son’s true thresholds. His left ear thresholds are likely better than what is indicated and his right ear thresholds are likely worse.

There are limits on how high they can go on that right ear, and the limits are tighter on the bone testing than on the air testing, which is why it looks like there is a gap. They had to stop sooner with the bone conduction. But remember these aren’t the levels were they got a response, they are the highest levels they tested at and there was still no response.

Information will be confirmed and filled in as he gets older. Does he have another test booked in a few months?

I’m glad you switched clinics. I wouldn’t have trusted the first one either after those results.

#3

First, thank you for advocating for your child and pressing for further testing.
Second, I wonder why bone conduction testing was not performed in the left ear? I agree that you will know more as the child grows and gets older. One “normal hearing ear” is sufficient for speech and language acquisition, but I wouldn’t settle there. If his air/bone is normal in the left ear, did the audiologist discuss a bone conduction hearing aid?
Thank you,

#4

Because that ear is normal. This kid is under 6 months old.

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#5

HI Neville,

You are right. I called our audiologist to clarify and she said those were not numbers where he heard at but the maximum limit that she was able to test at.
Another thing that still bothers me with the different testing result is for the first test, his air conduction was >90db at all frequencies. Second test, it was 60db at 500hz with gradual increase to >90db at 4000hz. I asked the audiologist why there was a difference, and she said the second test result is accurate and her interpretation for the first test was wrong. However now in the third test, it’s >85 to >90 across the different frequencies. It’s confusing…

#6

He is getting his next hearing test at 9 months old.

#7

Testing isn’t as precise at that age, which is why he is tested and retested and retested to confirm as he gets older.

Don’t worry, you’re doing what you need to do. He’s going to be fine. He’s going to be wonderful.

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#8

I’ve still seen conductive components when an ear is “normal”… just asking.

#9

Sure, but you are limited by the age of the child. There are limitations in the ABR system in terms of how low responses can actually be visualized in the waveform, and consider also how they would have masked appropriately since they are already at the limits of the system in the other ear.

Even after ABR, up until 3-5 years (depends on the child), you aren’t getting true thresholds with children you are only getting minimum response levels. So, for example, a 2 year old with perfect hearing may not respond in the booth well behaviourally to anything under 20 dB HL even though they can hear down to -10 dB HL, so once you get that through air there’s no point in doing bone. The auditory attentional system is still developing at that stage. Also, their overall ability to stay still and pay attention still sucks, so you don’t want to test down to soft levels if you are already within the realm of normal because you risk losing their attention and only getting results that day for one frequency in one ear. Bilateral masked bone at four frequencies in a 4 year old is a banner day.

An interesting note on the developing auditory system: I’m sure you’ve noticed that in adults if you are at threshold with one frequency and then suddenly jump to another frequency (or to the other ear) at that same level the adult will often miss it until you prime them to pay attention to that frequency (or ear) with a louder presentation. The adult auditory system attends to a particular tone and makes the ear (mechanically causes the ear to be) more sensitive at that frequency and less sensitive at others. This system isn’t in place in young children yet, so around 5-6 years of age you can often get them down to threshold and then just skip right across frequencies and from ear to ear at that level and they will respond the whole way along. It’s neither here nor there, just a nice demonstration of development in action.