The clinical significance of the bifid or "W" pattern reversal VEP.

[Sidesteps]

No question --- just wanted to pass on some information I found regard VEP's. My VEP shows a "W" pattern in the N145 segment as well as just prior to the P100 in my left eye on certain waves. The technician indicated it was an abnormal response but the test itself indicated within normal range on the latency. I think I'll be requesting a second VEP with better equipment (my test was on a 6" x 6" red/black screen which appears to not be optimal.)

I thought all of you that have had normal VEP's in latency might find this interesting....


"Although the visual evoked potential (VEP) to an alternating checkerboard stimulus is usually recorded from the occipital midline as an N-P-N complex with a major positive deflection at 100 ms (P100), a wave form exhibiting a P-N-P or "W" morphology is occasionally encountered and its interpretation is the source of some controversy. A retrospective chart review identified 15 patients exhibiting the "W" VEP. This represented 7.6 percent of 197 VEP studies and 5.1 percent of 394 eyes. The response was encountered in 1.7 percent of 57 normal patients and 21.4 percent of 56 patients with definite, probable or possible multiple sclerosis (P less than .001). The "W" response was considered normal in only one patient. Of the remaining 14 cases, 13 had definite, probable or possible MS and one had ischemic optic neuropathy. It is concluded that the "W" VEP is an aberrant response that is rarely seen in normals and may have the same significance as a delayed P100 latency."

[drsdonthelp]

Thanks Sidesteps,

I hope your new doc. can help you out as well. I have a calendar appt. book I bring with me to every single appt. and am constantly writing up questions to ask. If I don't I will forget!! LOL

Good luck to you!
Pam

[Sidesteps]

I have REALLY good vibes about this team for you and with your other health concerns that is exactly what needed to happen a long time ago for you. I don't understand some doctor's. I really don't.

I am hopeful about my new doctor. I should start compiling my list of questions and concerns now. My memory isn't as it once was.

[drsdonthelp]

Yes I have,,,,, and as a matter of fact, I have my timeline in my journal and also my long winded story of my medical journey..

This neuro told me that my problem is epilepsy (abnormal EEG) correlating to my slurred speech that lasted for two weeks  one year apart from eachother, and my Thyroid Eye Disease is the reason for the (abnormal VEP) and then went ahead and said "possible central sensitization" .

I have to say that at least now I have my Endo. his NP and my FNP all getting my records and reports together to send me to the NIH.. I hope I am accepted. At least now, they all get it!!

They all were like, "How did he explain the report to you?" When I told them, that's when the phone calls started to go between the three. I hope they can get me the help I need.

Thanks so much and Big Hugs,
Pam

[Sidesteps]

"The main characteristic of optic neuritis was P100 amplitude reduction, and of confirmed MS was P100 latency delay. There was a progression of the P100 latency delay and of the P100 amplitude decrement in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS. These results indicate a progression of demyelination in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS."

This is what I found interesting for me --- I have a slight delay in my right eye and a pretty significant decreased amplitude in my left eye. I found it interesting that your doctor never mentioned demyelination as well.

If you have a P100 latency, that's a pretty signficant finding. Have you had more than two clinical attacks but no lesions? I'll look at your profile closer. :)

[drsdonthelp]

It looks to me that my P100  > absolute prolongation in latency consistent with demyelinating process would indicate that the cause is MS related.

It's amazing that when the neuro called me to go over my results he did not even mention the word demyelination even though it was written in his report.

I am now definately all the more convinced that I in fact do have ms.
I am tired of the waiting game and the putting me off and the anxiety card or fibro. dx.

I think I posted my entire report of my VEP on one of my posts. I did look at your VEP but I am sorry to say I have no Idea what I am looking at..LOL  LOL

Thanks for putting these articles up, I actually am starting to understand alittle more about all of these medical terms.LOL kinda!!

Thanks a bunch,
Pam

[Sidesteps]

Here is another article. It appears that amplitude is also a significant finding in VEP's.

Abstract
"To investigate visual signal processing in patients with optic neuritis, suspected multiple sclerosis, confirmed multiple sclerosis (MS), and optic neuritis combined with MS, pattern reversal visual evoked potentials (VEPs) were recorded in patients and normal subjects. The amplitude and latency of the first positive peak, P100 were determined to assess electrical conduction in patients as compared to normal subjects. Suspected MS patients did not differ from normal subjects in peak latencies or amplitudes. The P100 amplitude was reduced in optic neuritis, confirmed MS and optic neuritis combined with confirmed MS. The P100 and N145 latencies were prolonged in optic neuritis patients and confirmed MS patients as compared to normal subjects. The main characteristic of optic neuritis was P100 amplitude reduction, and of confirmed MS was P100 latency delay. There was a progression of the P100 latency delay and of the P100 amplitude decrement in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS. These results indicate a progression of demyelination in optic neuritis, confirmed MS, and optic neuritis combined with confirmed MS."

[Sidesteps]

I am still researching this as well. Funny, I was even looking yesterday.

Did you look at my VEP? It's on my profile page.

I'm pretty confident that my left eye shows a weak bifid pattern (the W in the P100) as well as reduced amplitude. This is what the technician was seeing. You will notice on two of the patterns the N75 is weak with lots of movement prior to the P100 dip.


Here is one of the articles I read. It isn't just a P100 latency they should be analyzing. I found it fascinating. I also read that a scotoma can show on the VEP. I have a center field scotoma. It is small but seems to be increasing in size since the first time I saw it or I have two small scotoma's.


"VEP changes in MS patients are due to the demyelinating process which causes conduction alterations as well as inhibitory mechanisms. The pattern-shift VEP can show a delay of the main positivity, a diminished amplitude or/and an altered shape and duration. Concerning to series from the literature and own observations on more than 500 MS patients 4 different types of VEP alterations can be observed: 1. NPN complex with P2 delay; 2. broadening with loss of N2 and P2 delay; 3. bifid P2, P100-P135 complex; 4. deformation and dissociation with loss of P2, N105 dominance and amplitude reduction."

[drsdonthelp]

Just thought I'd bring this up again, since it is still weighing heavily on my mind.  Thanks sidesteps for starting this topic, it is very hard to research this and soak it all in, but with all of the wonderfully smart people on here, they can break it down alitlle clearer.

Pam

[drsdonthelp]

I haven't asked my doc. about it, but I have done some research.  It appears to be that when it is optic neuritis, the latency is more prolonged, and with optic neuropathy, it isn't.

I wish I could remember where I read it from, or even if I was able to quote it, but this definately changes everything for me....
Unfortunately, I did not go to my neuro. appt on Monday because
#1 he doesn't even know that I had the test done, I went to a different neuro.
#2 He doesn't listen to me and he basically tells me that I have anxiety for every fartin thing!
#3 I brought this up to my family doc. and I told her that I want to go to someone new with these new results.

I will probably contact my opthalmologist and discuss these results with him to see what he thinks.

I hope others can chime in to keep this discussion going. I need to learn more about this.

Thanks so much,
Pam

[Sidesteps]

I think there have been other studies on this... as this was one out of several posts about the abnornal waveform. I am not sure how many total studies have been done so far. (I did not even notice the date of the study.) I just found it interesting.

@Pam, I think ischemic optic neuropathy can reflect a P100 latency. I am not sure how they tell the difference except I think ischemic lesion "appear" different. Have you asked your doctor this?

[COBOB]

The typical Optic Neuritis is a P100 =>120mS and a "well preserved waveform."  There are waveforms other than the normal n-p-n.  

One of the problems with measuring signals in the human body is that there is no "zero base line."  The is no reference, so everything (EEG, ECG, etc.) has to be measured with a "differential amplifier."  Some people have "inverted ECGs" as a normal variant.  

It is interesting that there seems to be a relationship between MS and the W waveform morphology, but less than 200 VEP studies were used and of that, there were only 56 studies from people with MS or probable MS and of those, 13 had the "W" morphology.  

While the probability of a special event is = to the number of times the special event happens divided by the total number of events,  this study was based on an unblinded retrospective analysis of charts and a relatively small sample set.  

This is one of those cases where the results are "interesting," but anything more than that is a stretch.  It is basic science that should lead to more "designed" studies, but the result have to be taken "as is."  This small a sample in one study can not prove a causal link.  The link between demelination and signal latency along an axon has been demonstrated in the body and in lab.

Bob  

[drsdonthelp]

Hi,, I just recently had the VEP test done, and it came back abnormal. The impression read, that the P100 latency had absolute prolongation consistent with demyelinating process.

I have been doing a ton of research to see if my dx of ischemic optic neuropathy can cause the prolongation and from what I have been gathering, iits a demyelinating process that causes it.

If you understand this , I could use some help, I don't really know how they can tell the difference, but apparently they can tell the difference some how, I just wish I knew.

Thanks so much for bringing this up,
Pam

[Sidesteps]

That came out poorly. LOL! Hopefully you can read between the lines ....

I mean to say "I believe it means that not only is a P100 latency a significant indicator...."

[Sidesteps]

Shell, does it make sense to you?

I believe it means is that not only is a P100 latency a significant indicator of MS BUT they also are saying distortions in the VEP pattern such as reflecting a "W" are also a significant indicator for lesions in the optic tract indicative of MS.

My left eye doesn't reflect a significant "W" but it is not smooth which is normal. (I posted my VEP on my page and you can see a difference between the left and right eye patterns.) The left eye has abnormal distortion which I think is why the technician was saying it was abnormal. That is the eye my scotoma is in as well.

This will be a question I ask my new Neuro in June. I'll update with more information.

[sllowe]

Thanks for the info, S-steps. Re-reading it to wrap my head around it. And, providing a healthy bump for others.
-Shell