Audiology/Otolaryngology/unilateral hearing loss
QUESTION: I have unilateral hearing loss in my left ear. The pure-tone audiogram suggests mixed hearing loss, moderate. Right ear is normal. I also have unilateral tinnitis, left ear. The speech test indicated 88% correct answers in left ear and 100% in the right ear. The ear drum is retracted and I have eustachian tube dysfunction, left ear. I was told I have possibly otosclerosis of the left ear. The ABR was done and was negative, however I've been told that I need to return in 6 months for another hearing test. The doctor said the ABR is only 85% accurate and that there could be a tumour. I'm confused as to why he may think this. Doesn't otosclerosis explain the hearing loss?
You ask a good question. Eustachian tube dysfunction would explain a "retracted" eardrum and sometimes tinnitus. If this has been chronic (long-term), then I would hope some medical treatment to alleviate/improve this condition would be tried. Moderate mixed hearing loss can definitely be the result of otosclerosis (look for "classic" presentation with bone-conduction "notch" at 2-3kHz on the audiogram). Otosclerosis is more prevalent in females following child birth years. Additional audiologic testing, including acoustic reflexes and otoacoustic emissions (OAEs), can help differentiate this disorder from a couple others.
Auditory Brainstem Response (ABR) testing is sometimes performed as a neurodiagnostic test (as opposed to hearing loss estimation with infants) when a tumor of the VIIIth nerve is suspected. Neurodiagnostic results are concerned with quality and timing of the waves (which correspond to different points along the auditory nervous system). These results are typically reported as "normal" or "abnormal" when compared to normative data and your opposite ear. I assume that "negative" in this case means "normal".
The doctor (either audiologist or ENT physician) who stated that the ABR is not 100% sensitive to detecting tumors is correct--but this is rarely the case for any test (including an MRI, which is the other test which is used to find tumors). This being said, the typical presentation of an acoustic neuroma/vestibular schwannoma (VIIIth nerve tumor) is that of unilateral (or asymmetric) sensorineural hearing loss, more often gradually affecting high frequencies along with presence of poor word understanding and tinnitus in the same ear. Also, dizziness or instability can sometimes be present.
Mixed hearing loss (both conductive and sensorineural) where you have a middle ear problem along with an inner ear/nerve problem does complicate the diagnosis. You are correct, Otosclerosis could explain both.
While not very likely at all that you would have a tumor, the doctor is being cautious. Other aspects of your history, which you did not include (onset, progression, etc) would be considered in determining your diagnosis, follow-up, and treatment.
Ideally, the ETD could be effectively treated first, then a re-evaluation performed without this confounding factor (as it could affect a couple other tests).
I know this is not a clear-cut answer, but hopefully the explanation helps your understanding of why multiple tests are often performed and that things do not always fit neatly into a diagnosis. We are talking about a very complex system and pathway which cannot be entirely observed, so indirect measurements give us clues, but not always the definitive answer at first.
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QUESTION: I left out that I am 61, hearing loss started about 10 years ago and gradually got worse, I feel a fullness in my left ear, which I guess would be expected. I also have some minor problems similar to being dizzy or disconnected. My MD I believe is an otolaryngololist???, I got the report from the ABR, it says the absolute and interface latencies in the left ear are slightly longer as compared to the right ear. He explains this as a result of my hearing loss. The IT5 = 0.25, not sure what this means. MR told me to return if any of the symptoms get worse. Would love your opinion again, I'm just a little concerned. Thank you very much, it's nice to have someone to ask questions to.
I would say that your history and symptoms are fairly consistent with otosclerosis with the addition of ETD. The otolaryngologist (ENT) is likely reading the report from the audiologist who did the testing. A conductive hearing loss will prolong all the absolute latencies, but not usually the interpeak (say between wave I and wave III or V). Now, there is a normal RANGE that these can fall within and still be normal, so those values should be referred to. The report with the ABR should include interpretation. Most ENTs have a very low threshold for ordering an MRI to look for a mass, so the fact that your doctor is not is probably a good indication that he is not worried about this.
Just so you know (and maybe to ease your mind) in the very unlikely event you might have a tumor of the VIIIth nerve, these are typically benign, very slow growing growths which may have no major ill-effects for many many years. I have had patients who never had any treatment (just monitored), had focused radiation "gamma knife" to freeze/necrose it, and surgery to remove. Hearing loss is by far the most significant issue however it is dealt with (aside from the expected risks if you had surgery).
I do not think you should be concerned at all, actually, outside of dealing with the ETD and hearing loss. In other words, I believe it is HIGHLY unlikely that you have anything more going on based on what you have told me. Like I said, seek treatment/resolution to the ETD (which may help your dizzy/disconnected feeling). If your doctor is not as responsive as you would like, then it might be a good idea to seek another opinion.