Hi everyone, I wonder if anyone knows the answer to this.. do changes in the VEP test mean anything. Like a few years ago I had a VEP (normal range)... it was like in the 80s... now I had another VEP test and it was still in the normal range but it was higher in the 90s.. does it mean anything if there is changes.. I know it's still in the normal range but wonder if it means anything?
Still normal. VEP latency changes with age. The highest positive peak (typically called P100) should happen in less than 115 mS (milliseconds) for people less than 60 years old. People 60 and over are considered normal to 120mS.
Studies show that 85-90% of people with definite MS and 58% of people with probable MS have abnormal VEPs. If you have had Optic Neuritis, you will have an abnormal VEP.
I had two abnormal VEPs, when I had my first initial attack, I have palor of my optic discs and I had stabbing pain at the back of my eye and I also had abnormal field tests.
My subsequent field tests and VEP was normal. My Eye Dr said retraobular sp? optic neuritis, but my MRI etc. was normal, my current neuro who has not access to these old records doesn't seem to think my discs are that pale, but everytime I go for an eye test with the optomertrist they comment on the palor in my right disc. I have no idea, but I did have vision problems at the same time I had other symptoms but my new neuro seems to think that might have been migraine.
By definition Optic Neuritis is a demyelination of the optic nerves, chasm,and/or tracks. If the optic chain demyelinates, then the conduction velocity decreases and the latency increases. You can have other conditions, but the VEP is diagnostic for ON.
The textbook says:
With abnormal VEP, some of the differential diagnostic considerations are as follows:
Normal VEP virtually excludes an optic nerve or anterior chiasmatic lesion.
Clinical usefulness of VEPs includes the following:
More sensitive than MRI or physical examination in prechiasmatic lesions
Objective and reproducible test for optic nerve function
Abnormality persists over long periods of time
Inexpensive as compared with to MRI
Under certain circumstances, may be helpful to positively establish optic nerve function in patients with subjective complaint of visual loss; normal VEP excludes significant optic nerve disorder
And I pulled another text:
The Clinical Neurophysiology Primer By Seward B. Rutkove
5.1 Optic Neuritis
"Optic Neuritis and MS are the primary concerns in the assessment of the optic nerve. Approximately 90% of patients with a definite history of optic neuritis have delayed P100s. Acutely, a normal VEP makes a diagnosis of optic neuritis very unlikely, especially with sever clinical symptoms. Acute optic neuritis, whether part of MS or not, produces a marked prolongation in the P100 in the effected eye. Over weeks to months, visually acuity usually improves, and approx 5% may return to normal after years. An abnormal VEP in an eye that appears normal clinically suggests an old optic neuritis with clinical recovery. Often, the VEP will improve also, though it seldom returns to normal. If an optic neuropathy is clinically evident before testing, the VEP will not add to the clinical impression."
The way I read this is Optic Neuropathy may be clically diagnosed and the VEP will not help. Acute Optic Neuritis will always have an abnormal VEP. Old cases of ON may see the VEP latency improve, but seldom returns to normal.
One gotcha here is that Optic Neuropathy and Optic Neuritis are not the same thing,
I was initially diagnosed with Optic Neuropathy poss Optic Neuritis. Once I had the abnormal VEP, they changed the DX to Optic Neuritis.
Thanks for the info....all I know is that I was DX with Optic Neuritis by an Opthalmologist after my exam showed a visual field loss, colorvision loss, and RAPD.
I guess I fall into the 10% that doesn't have an abnormal VEP.
After all this talk, I decided to pull out my VEP results. My P100 latency was 104msec. I know that is just slightly above the average, and within the normal limits of most ranges.
I did find one book that sited 87-104 as the normal range for VEP P100 latency.
Clinical Neurology and Neurosurgery
Volume 85, Issue 4, 1983, Pages 267-272
Hmmm, this makes me wonder...I have a delay in my left eye. it was 8 milliseconds in April and increased to 10 milliseconds in August. This, along with a second bout of vertigo, clinched my diagnosis.
But, I'm wondering if I misunderstood my neuro and the delay was 108 & 110? He also called it a VER, is that different from VEP?
I just found this online:
If I'm reading this correctly...a normal VEP will have 100 milliseconds from the time you see the pattern and the time the electrode on the back of your head detects your response. So, if my VEP had a 10 millisecond delay, that means it took 110 seconds for the electrode to register my response?
Good question....you would have to ask your neuro if the delay was based on the average of 100msec or the delay was 8 and 10 msec above the highest normal range number. Like 114msec plus 8 and 10, for a total of 122 and 124msec for the visual response to get to your brain.
The 100msec is the average time for the visual response to get to the brain, however the normal range is somewhere between 87-114 or 87-104.....are the two ranges I have found.
VER Visual Evoked Response is the same as Visual Evoked Potential
Currently, most labs consider responses less than 115mS to be normal, but if one eye was in the 85mS and the other eye was 114mS that might indicate an issue. An the waveform shape has to be considered too, If the slower eye has a decreased amplitude compared to the faster eye, there could still be demyelination. The P100 value is based on a statistical norm. Not everyone falls in the statistical norm.
Thanks for sharing this info, it is very interesting and educational, on this basis then as my VEP has since returned to normal I am assuming that I did not have Optic Neuritis.
My original Neuro who did the testing sent me for an MRI based on the results of the VEP, but 6 weeks later my VEP was normal, he suggested that perhaps I had a migraine at the time of the test. The eye Dr is still saying that he thinks I had an attack of retrobulbluar neuritis?
My new neuro thinks all is okay with my eyes etc. he thinks I just get blurry vision because of migraines and I must admit since I have been on migraine meds I have had no blurry vision, no shimmering, no stabbing pain, no eye twitching everything has been brilliant with my eyes and my vertigo, shame it has not fixed the actual headaches.
I just had a VEP and A BAER test - got the results yesterday - the diagnostic center are the ones that told me I was being checked again for MS ... my appt is not for 45 more days I just need help seeing if my tests are normal - where can i check my numbers?
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