VEP P100 latency absolute prolongation consistent with demyelinating process

[drsdonthelp]

Hi Doctor, I am fairly new to the eye care forum and would like your expertise regarding a recent VEP test that I had done. It came back abnormal due to prolonged latency, My number was 127.? ms, can't exactly remember off the top of my head. I was dx'd with ischemic optic neuropathy in 2007. I also have had orbital decompression surgery due to Graves eye disease. Three to Four months following my orbital decomp. surgery, I had speech slurring for two weeks and then my right eye became very blurry. My eye test for my right eye was 20/70, 6 months later it was back to 20/40.

My question is, Is there a difference in the VEP test that can tell if it is optic neuritis due to demyelinating disease (MS) or would the latency of the P100 also be prolonged due to Optic Neuropathy?
I am trying to understand my report, since I am going through a process of being tested for MS.

I greatly appreciate it,
Pam

[John C Hagan III, MD, FACS, FAAO]

Best of luck Pam.

JCHaganMD

[drsdonthelp]

Dr Hagan,

I Thank you from the bottom of my heart for taking the time to help answer my questions.

I am very grateful to be a part of this forum,  it is a huge help!

Take Care and God Bless!
Pam

[John C Hagan III, MD, FACS, FAAO]

Optic neuritis is one for of optic neuropathy (which means literally a sick optic nerve). Most cases of optic neuritis including MS do get better, many clear completely. Optic neuropathys due to glaucoma, compressive neuropathies (trauma, tumors), ischemic neuropathies (example temporal arteritis) often do not improve or get worse.

I do not claim to be an expert on neurophysiologic testing of the eye but I would never make a diagnosis based in just changes in amplitude and latency of the test.
JCH MD

[drsdonthelp]

Thank you for your response.
When I read my report from the neuro. it stated that the test was abnormal due to absolute prolongation in latency consistent with demyelinating process.

Anytime I had done some research on this, I found that the amplitude would change in optic neuropathy but the latency would be prolonged with optic neuritis. I have prolongation in latency.

When I had my first surgery in 2007 was when they found the change on my optic nerve.  Three months later my eyesight became worse with blurriness, color change. Then six months later it got alittle better.
I am confused because I was told with optic neuropathy, my vision will either be stable or get worse, but not get better. I have read that with optic neuritis, the changes in my vision could potentially get better, in which mine  did. It is still not good, but better than what it was.

I am sorry if this sounds confusing, I would greatly appreciate your input on this.
Thank you for your time,
Pam

[John C Hagan III, MD, FACS, FAAO]

1. No the test would not distignuish between optic neuritis due to MS or idiopathic or trauma or ischemic arteritic or non-arteritic optic neuropathy.

JCH MD

[drsdonthelp]

Please excuse my moniker, I have not had much help from my local doctors. :)