Question about IgG and VEP

[mythsayer]

My neuro said my LP showed no O-Bands, but he was confused because the lab wrote "IgG not calculated".  He said they always give a count and he'd never seen that before.  He was going to ask them about that but he had no idea why they would write that (and they sent like 8 different results over from the pending tests, so was something they did consistently).  Any ideas?

Also, my VEP was flagged as abnormal. The latencies were 96 (left eye) and 108 (right eye), so within normal range, but it was flagged as abnormal because, as my neuro said, they eyes should have latencies close to each other.  He still wasn't ready to make a diagnosis, even though from what I've read (in actual medical journals and clinical books, like MS diagnosis books for doctors and medical students), anything over 10 is completely abnormal.  I've also read that the delay between they eyes is the most sensitive VEP test for ON, even if both latencies are normal.  Apparently such a large delay is almost always indicative of an optic nerve lesion.  My doctor was interested in the difference and said it wasn't normal, but he also wasn't ready to say it was ON even though everything I've read says it most likely is (either early in disease or older disease that healed a little).  The books say you can either be abnormal with a high latency OR normal latencies and abnormal delay (and everyone seems to agree that 6 to 8 is the cut-off but definitely 10 at the highest).  Anyone have any experience with a VEP that turned out like that that was finally diagnosed with ON?  I'm seeing the neuro opthamologist on Monday but just thought I'd ask around.

[HVAC]

MS LP's are usually sent to several different Labs. One is usually the Mayo. Mine took six weeks because it was sent to several different labs across the country. I am at Duke but they did not use the Duke lab for a MS LP.

Alex

[mythsayer]

http://books.google.com/books?id=JKjCFIGUqcIC&pg=PT79&dq=interocular+latency+difference&hl=en&sa=X&ei=dkUKU7qjLYLtoASz9YGAAg&ved=0CDgQ6AEwAg

Here is another book saying what I just wrote (over 10msec).  I will let everyone know what the doctor says tomorrow. I fully expect him to brush it off as that is the way my life goes, but you never know. About two years ago, I had blurry vision in my right eye that drove me to the optometrist  and he said I had 20/20 vision that was just blurry 20/20, which makes no sense to me. The glasses I got (because I couldn't see well despite apparently perfect vision) didn't help and actually made it worse. Now I'm having bouts of double vision. Always in the right eye, which was the higher number. Even my neuro was "concerned" about the 12msec delay, but not enough to diagnose me, so he sent me to the opthmologist (tomorrow).  He did say, however, that if there is evidence of ON now or in the past, he's diagnosing me. So I have a lot riding on this.  But I'll ask about the delay. It might be helpful, like I said.

[mythsayer]

http://books.google.com/books?id=JKjCFIGUqcIC&pg=PT79&dq=interocular+latency+difference&hl=en&sa=X&ei=dkUKU7qjLYLtoASz9YGAAg&ved=0CDgQ6AEwAg

Here is another book saying what I just wrote (over 10msec).  I will let everyone know what the doctor says tomorrow. I fully expect him to brush it off as that is the way my life goes, but you never know. About two years ago, I had blurry vision in my right eye that drove me to the optometrist  and he said I had 20/20 vision that was just blurry 20/20, which makes no sense to me. The glasses I got (because I couldn't see well despite apparently perfect vision) didn't help and actually made it worse. Now I'm having bouts of double vision. Always in the right eye, which was the higher number. Even my neuro was "concerned" about the 12msec delay, but not enough to diagnose me, so he sent me to the opthmologist (tomorrow).  He did say, however, that if there is evidence of ON now or in the past, he's diagnosing me. So I have a lot riding on this.  But I'll ask about the delay. It might be helpful, like I said.

[mythsayer]

Agreed that small differences aren't a big deal, but "small" is defined as up to about 8... 12 is abnormal for sure. Nothing I can find says anything above 10 is within normal range. I'll see if I can find anything in the prior posts.

[essdipity]

I don't know the technicalities of the VEP. However, this subject has been discussed many times here, though not in a number of years, if I recall correctly. You might use the Search This Community function (magnifying glass icon at top) to see what has been said.

I found this old thread, which may be of interest. The response I draw your attention to is by Quix (Quixotic1), who is a pediatrician with MS. She used to post here very often, but unfortunately is seldom here these days. Of course she is not a neuro-ophthalmologist, but she has done a great deal of research on MS and its diagnosis, and has helped probably thousands of members here.

http://www.medhelp.org/posts/Multiple-Sclerosis/visual-evoked-potential/show/503609

As you will see, Quix finds small variations between eyes on VEP to be pretty much inconsequential.

ess

[mythsayer]

Don't know if that last link showed up: http://books.google.com/books?id=I6Q4_5WTshUC&pg=PA207&lpg=PA207&dq=interocular+latency+difference&source=bl&ots=LU1j6OzmTP&sig=wHpLUGIdp8EmAdbCt7NfneTc9MA&hl=en&sa=X&ei=7Y8GU5rcO8__oQSp0YHwAQ&ved=0CEAQ6AEwBDgK#v=onepage&q=interocular%20latency%20difference&f=false

You have to click over to the next page. Just seeing if anyone elses vep came out this way or to give others who are in limbo some more info if this affects them. I will see the neuro eye doctor tomorrow.

[mythsayer]

Yeah, that's the thing.... Most neuros ignore the inter ocular latency but apparently they shouldn't. My research (and apparently whoever flagged my vep knew something about this) indicates that an abnormal delay between the eyes is often considered more sensitive than just an abnormal latency. There have also been instances of the nerve remyelinating so as to fall back into the normal range. If the lesion is so far back so as to not see it on either MRI or visual inspection, ignoring this finding would miss a lot of eye problems (not necessarily ON but other things as well. Although it looks like this type of abnormality is almost always a lesion).  Take a look at this page from a book (I have others as well but this was easy to get to): http://books.google.com/books?id=trFI0pzT-DIC&pg=PA84&lpg=PA84&dq=vep+normal+latency+abnormal+delay+between+eyes&source=bl&ots=6jRZitxsKZ&sig=74Ka1l6gXOTKA6DC0Rk0G-DrlQM&hl=en&sa=X&ei=ryoGU4zWBYjboASS3oKoCQ&ved=0CCgQ6AEwATgK

And this one, but go to the next page: http://books.google.com/books?id=I6Q4_5WTshUC&pg=PA207&lpg=PA207&dq=interocular+latency+difference&source=bl&ots=LU1j6OzmTP&sig=wHpLUGIdp8EmAdbCt7NfneTc9MA&hl=en&sa=X&ei=7Y8GU5rcO8__oQSp0YHwAQ&ved=0CEAQ6AEwBDgK#v=onepage&q=interocular%20latency%20difference&f=false

[essdipity]

Hello. As far as I know, abnormal latency is 15 or more, one standard deviation for that test. I've never heard that a difference between eyes is cause for MS concern.

My own test showed that my right eye was definitively slower, so abnormal. MRI has not shown an optic nerve lesion, though my understanding is that if the lesion is relatively far back on the nerve it is harder to detect. Eye examinations have been normal, and I have never had optic neuritis. I do have MS.

ess

[mythsayer]

Sorry.... to clarify, on VEP, abnormalities can be either amplitude issues (I don't have) OR latency delay OR normal latency with an abnormal difference between the eyes.  I wrote it incorrectly above.