DPOAE Hair Cells and Tinnitus

[Ricky81]

Hi Dr. Nagler,

Have a question about my DPOAE test and if that is the cause of my T. My audiogram looks normal for my age. I'm in my mid 30's.

Background:
My T started 50 days after a physical assault to my ears and head which triggered High intracranial pressure and an ear infection. Note: I got a Lumbar Puncture to fix my ICP, my T lowered but did not go away.
My left ear is ringing more than the right ear.

1. Do you think the weak cochlear outer hair cell around 5700 Hz are due to the assault or something else?
2. Is the dip in my left ear around 5700 Hz causing my Tinnitus, if so why would my right ear ring?
3. Is my T more Neurological due to Head Injury.

Please see DPOAE chart.

My ENT thinks my T is more Neurological but I emailed my Audiologist and below is what he had to say.

Email from my Audiologist:
I suppose it is possible that the tinnitus is due to less robust cochlear outer hair cell function around 5700 Hz in your left ear , especially since the more recent tinnitus match you did came closer to that frequency than we originally though. However, like I said, the emissions are weaker but still present which means there is still outer hair cell function at that frequency. We may never know for sure one way or the other.

Another email from Audiologist before I measured my T to be around 6000 Hz:
The DPOAE generated by your ear is represented by the circle markers for the right ear and the circle/X markers for the left ear. From that perspective, the amplitude response of your DPOAEs as a function of frequency in your right ear is about as flat as they come. In your left ear, you are correct that there is a dip in amplitude at around 5700 Hz. It is possible that this reflects less strong cochlear outer hair cell function around 5700 Hz than at the other test frequencies, especially given that you reported stronger tinnitus in the left, although perceptually your tinnitus corresponded closest to a 3000 Hz tone. However, this dip just as likely reflects a stimulus standing wave artifact, which is very common for frequencies around 6000 due to the length of the ear canal.

The triangle markers below each DPOAE marker represent the noise floor for the same frequency band in which that particular DPOAE is measured. We are most concerned with the DPOAE signal to noise ratio, represented by the distance between the DPOAE marker and the corresponding triangle below it. All of your responses, even at 5700 Hz in the left ear, are robust with high signal to noise ratios, indicating that the cochlear outer hair cells are functioning throughout the frequency range measured. So I am not concerned that there is some problem that the MRI did not pick and I do not believe you should be either.

Here is a previous thread about my T.

https://www.tinnitustalk.com/threads/tinnitus-spikes-when-i-bite-my-molars.7361/

Thanks so much!

 

[Dr. Nagler]

Hi @Ricky81 -

Thank you for your detailed post.

I realize that your question is important to you - or you would not have asked it. The thing of it is - your question is not important to me. Now please don't get me wrong. YOU are very important to me, but your question is not. And I want to take a moment to explain why it should not be important to you either.

DPOAE is an excellent hearing screening tool and is moreover a very good reflection of outer hair cell function. But strictly in terms of tinnitus, DPOAE is purely a research tool and has no clinical application, at least not at this point in time.

When I say that it has no clinical application in tinnitus, what I mean is that it has no therapeutic or prognostic value. No tinnitus treatment decisions are based upon the results of a DPOAE, nor does it predict the outcome of any given treatment protocol or the clinical course of the condition in the absence of any treatment.

So since no clinical decisions are based upon the result of a DPOAE and since it has no prognostic value, I see no reason to ever order that test as part of a tinnitus work-up.

Now, back to your question ...

The answer is that I honestly do not know enough about the subtleties of DPOAE to comment responsibly. And even if I did, my response would not serve to change a thing in terms of your treatment options or your prognosis.

You have already been evaluated by an ENT, who has ruled out the (rare) causes of your tinnitus that can be fixed as well as the (even rarer) causes of your tinnitus that represent a threat to your health nor life. That having been accomplished, the real issues you should be looking at, in my opinion, strictly revolve around the degree to which your tinnitus affects your life and what, if anything, you want to do about the degree to which it affects your life. DPOAE plays absolutely no role in that regard.

I hope this response helps more than frustrates.

All the best -

stephen nagler