Wednesday, July 21, 2010

Audiological Angst

With a child who is hard-of-hearing, understanding what he can hear unaided vs. aided is often quite confusing. There are many times that Nolan shows a response to something (with his aids off) and we wonder if this whole thing has been a great big mistake. That he has normal hearing after all, and the tests have been one big giant error. Other times, he acts totally deaf, not turning to people calling his name or to other sounds that he "should" hear. Then we worry that he has lost more hearing, and this can cause a great deal of stress.

The one thing that gives us reassurance is consistent booth test results. After all, if the booth tests are consistent, then we can be fairly sure of the testing methodology. While we've had some fluctuation in the high frequencies with Nolan's hearing, his low frequencies have been fairly stable. His bone conduction scores have also always been stable, with his scores going from 50dB in the lows to 30dB in the highs. This is consistent with his ABR at birth, and with his OAE results at birth (absent OAE in the lows, but present in the highs).

That was true until today. Nolan's audiological testing threw me for a complete loop today. His bone conduction scores were the exact opposite of what they've been in the past. Nolan tested at 5dB at 250Hz, 25dB at 500Hz, and 25dB at 1000Hz.

Big difference from 50dB, yah?

And so now, it looks like this all might have been one giant, colossal mistake. Could Nolan's loss have been conductive since birth? He had no fluid or ear infections at birth, and his CT scan shows a normal ossicular chain. So really, it doesn't make any sense (especially in conjunction with the missing DPOAE in the lows, which were present in the highs). Sure, he's had some fluid and infections since he turned about 1 year old, but his first tests were prior to all the infection hullabaloo.

The amount of anxiety this produces is insane. For instance, the type of device that Nolan is using might be inappropriate if his loss is primarily conductive. A BAHA would be a more appropriate hearing aid for him (if this is true). Or, possibly, the conductive component could be corrected if the source could be found. With a 60dB conductive loss (his air conduction thresholds are fairly similar to his test in May), something is drastically wrong with his middle ear system. This kind of loss isn't caused by tubes- especially since he's had it since birth. The CT scan showed a completely normal middle ear, so there isn't anything really wrong with the bones there.

Which is why I have a hard time believing the latest test results. With a normal middle ear (no fluid, normal ossicular chain, PE tubes), a child shouldn't have a 40-60dB conductive loss. Nolan also doesn't have a craniofacial syndrome, which rules out other strange anatomical things going on. Then there are the bone conduction tests obtained at home, which are all consistent and show a 50dB rising to 30dB loss (which is consistent with his air conduction booth test in May 2008).

Anyhow, Nolan is not hearing at a normal level. His air conduction thresholds are still moderately severe across the board for the left ear, and are at a moderate level for the right ear. Bone conduction does show a sensorineural loss for the 2-4KHz range, so he doesn't have an air-bone gap at the higher frequencies. For the first time in his life, he shows a sloping sensorineural loss.

Our audiology clinic at home shows a moderately severe to moderate loss, with a possible slight conductive component across several frequencies. John Tracy is showing a moderately severe conductive loss in the low frequencies, with a moderate sensorineural loss in the high frequencies. Now the question is: which one is right? Has Nolan been misdiagnosed all along? Or are we getting "false" bone conduction readings?

We may ask for a referral to House Ear Institute to sort this all out. If only there were an objective way to get bone conduction scores!


susannah said...

wow. that must be a ton to digest and sort through...:( i hope you guys get more definitive answers asap & that it doesnt overshadow everything else at jtc!

Herding Grasshoppers said...

I have no idea if this could apply to Nolan or not, but...

Tate sometimes feels the tone during bone conduction testing, as opposed to hearing it. He must be feeling the vibration caused by the sound waves???

Especially after he lost almost all the residual hearing in his left ear.

At this point (he's eleven) he's sophisticated enough to tell us when he's feeling it but not hearing it. I suppose because it's turned up so loud the vibrations are stronger.

Like I said, may be completely irrelevant to the testing on Nolan, but just thought I'd throw it out there.


PinkLAM said...

I hope you guys are able to figure everything out ASAP, both for Nolan's hearing sake and your own sanity. I can only imagine how frustrating it is not to be able to get a single answer by just doing a test.

Is it possible he has a fluctuating sensorineural hearing loss with a conductive component? I know next to nothing about conductive hearing loss, so if that suggestion makes no sense, then sorry, just ignore it. As far as Julie's comment- I also have experienced it where I "feel" the bone conduction rather than hear it. I don't think that would occur in such a low dB volume. I've typically only had the sensation when it gets up to the 90/100 dB range. However, anything is possible.

rouchi said...

Wow, that is a lot to worry about.I really am now worrying if the tests we have done for Prisha in India are correct or we need better ways of finding out her levels.I really hope you are able to figure this out soon.I am glad that ur trip is proving so beneficial to parents like us who have little help in India.

Julia said...

Oy, what a snarl of conflicting information! I would definitely seek the House opinion, since you're there anyway. Well, either this latest test is wrong and an anomaly, in which case you'll be back to where you were (which has the advantage of familiarity!), or it's a huge leap forward in terms of putting this giant puzzle together. And while a BAHA means surgery, I've heard that kids do great with it, and if it turns out to be the right way to go, it could be a great way to give him clear, bright, consistent sound and get past the hearing aid roller coaster.