Understanding ENG's and caloric tests

Medical Tests 🔬
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If the caloric test (bithermal irrigation) portion of an ENG/VNG comes back with normal, is this evidence against (or does it outright disprove) the idea of vestibular neuritis / labyrinthitis?

All four go-rounds (cold right, cold left, warm right, warm left) produced “robust and symmetrical nystagmus.” All it says was that “left ear response 7% weaker” and “right-beating response 17% stronger.” (I’m not sure if this implies any vestibular impairment. Does it?) The eye speed was 159 deg/sec.

All of the following were normal (for nystagmus): headshake, gaze-vertical, repeat gaze-vertical, gaze-horizontal, repeat gaze-horizontal, spontaneous nystagmus, Dix-Hallpike left, Dix-Hallpike right.

Abnormal portions were the oculomotor tests (saccade-random, repeat saccade-random, OPK-fixed and repeat OPK-fixed). The first two showed some long or borderline-long latencies for moving targets; pursuit was slightly asymmetrical; and the two optokinetic (OPK)-fixed tests had somewhat low gain and asymmetric response, both with “gain lower for rightward moving targets.”

I think Hain previously said, however, that some of these things (including a strabismus) were already noted and probably due, in his opinion, to a slight congenital nystagmus – in other words, likely unrelated to the present problem.

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Hi George,
What did you doctor say about the results?

Lisa

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George,

The thing about the caloric test is that it is notoriously unreliable. Halmagyi wrote a review about this saying that there were a number of problems both with the results and worse, the person interpreting the results. I think unless the results show a really trashed inner ear (as in a huge loss of function), I would take the results with a grain of salt. I’ll dig up the paper if you want … it may already be posted here but can’t remember.

How did you cope post caloric test? Did you feel worse for a long period of time or was it all over that day? I was trashed for 2 weeks afterwards back in November 2003. When they asked me to revisit the caloric again two years later I told them to take a flying leap. I’ll never do that again.

Scott

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Lisa: The doctor has yet to give his opinion on the results, so I (in my incorrigible fashion) am working to make sense of it myself.

General notes: I found out about the 17%. That’s directional preponderance. Hain says that “it should be 35% or less” (only if not is it abnormal). He adds, “There is little if any clinical value in DP.”

I also found four numbers, the SCV’s (slow-component velocity), one for each of the four parts. Hain says the four numbers should be summed, and “the total response should be 20 or greater.” This, the total eye speed, is in degrees/second. So there’s the 159 I reported earlier = my four values were 22+52+42+43 = 159.

Lastly, Scott: Well, I’m not an expert, but Hain doesn’t agree with Halmagyi. Actually, Hain says, there’s a lot of potential for error in testing or results – so I called his clinic and asked them to recommend a reliable place (one they trust) for a reliable ENG including the caloric test.

He says: “[ENG’s are] the gold-standard for diagnosis of ear disorders affecting one ear at a time. For example, the ENG is excellent for diagnosis of vestibular neuritis.”

As for the interpreter, the audiologist wrote up only a purely objective summary of the results. Hecox (who I think is still stuck on VN, but is a neurologist) will get his shot at interpreting these results, as will Hain. I intend to send him a packet of all the test results I’ve had since my folks shoved me away from him. (That’s because I intend to go back to him, whether they like it or not!)

Either way, I’ve already deduced that there is absolutely zero evidence of vestibular loss. At most there is perhaps a slightly dominant side (the right side), but that’s meaningless.

As for what happened, I got my first taste of spinning vertigo, which initially scared the hell out of me – I nearly took off the goggle unit and stopped the test. They didn’t tell me it would induce vertigo – they just said it might make you dizzy or uncomfortable. And it’s a NASTY sensation. But, it faded after about five minutes. I was fine afterward. I even went and put in 5 hours at the office.

My original question, however, had been, simply, ‘If an ENG / caloric test is normal, can you pretty safely rule out VN?’ After all, doesn’t “uncompensated VN” mean impaired vestibular function that has not corrected?

Bottom line, if Hecox reads these results and STILL says “I think you have VN,” his days as my specialist WILL be numbered!

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The caloric test kicked my a**! It was horrible. I cried, hyperventilated, threw up and had to stop the test multiple times…but eventually made it through all 8 cycles. It took me days to recover also. However, Dr. Hain did use these results to rule out VN which I was originally diagnosed with by another doctor.
Sarah

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I actually was the one who proposed an ENG to Dr. Hecox after he had the posturography test. I got bold enough to e-mail him that “some doctors [and I meant Hain] consider posturography fairly insensitive to vestibular function and thus recommend it be used in conjunction with an ENG.”

Part of what bugs me about Hecox’s recent insistence on VN is that Hain already ruled it out! On his site, Hain says, “Experienced eyes (with Frenzels) are far more reliable than most ENG’s.” Hain did some balance / equilibrium tests on me, and also used the Frenzel goggles, and he noticed the same mild abnormalities / deficiencies in the oculomotor reflexes.

So all the ENG did was (a) show the same things that Dr. Hain noticed purely by observation, and (b) show zero impairment (via caloric testing) of vestibular function.

… You know, I feel like I know more about even VN than Hecox does, if he doesn’t even realize that VN was already out once Hain examined me. I’m waiting for Hecox’s reaction when he sees the normal-results caloric test!!

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HI George,
I had a very similar experience when I brought the results of my VNG (ENG) to this much older vestibular disorder neurologist. His name is Bernard Cohen and he taught all these docs we are now discussing. He’s in his late '70’s. If you look him up, he was the one who worked with the original astronauts that came back with dizziness issues and the sailors from WWII who had MDD from being out to sea for so long…

That being said, he refused to even look at the VNG test I brought to my appt. with him, said they were nonsense (maybe a little harsh), said that the computer just reads it and is not very accurate. He then, just as Hain did, took out his Frenzel goggles and did a very extensive exam. Many of the younger docs barely examine us anymore. They love to send us for tests:-)

I do think with MAV it best diagnosed by taking a good history and physical exam. Dr. Newman did not request vestibular testing.

Hang in George. You are getting closer to a definitive diagnosis. It’s just unfortunate to do this you have to fight to prove a doc wrong!
Lisa