I had ON diagnosed in Dec. it was diagnosed based on my symptoms of eye pain on movement, and the present of a Marcus Gunn pupil. The neurologist subsequently noted pale optic disc after I saw them in March.
due to a previous un diagnosed episode a few years ago (which they now think was a CIS myelitis), and the emergence of L’Hermitte in Feb, they have been looking for MS.
I was was sent for VEP and MRI brain and full spine. VEP came back negative and MRI showed clear brain, but what looked like several intensities at c5 c6 posterior cervical cord. I am still waiting to be told what that means and what happens next.
this morning I have received a letter inviting me to another neurophysiology appointment to conduct VEP again, but also 3 other tests which I can’t seem to find out about:
Electrooculogram (EOG)
Electroretinography (ERG)
Pattern Electroretinogram (PERG)
I wondered if anybody had an idea about what the purpose of the tests might be? Are they now looking at another diagnosis?
i know I should wait to find out but have been waiting since I had my my evoked potentials in April, and my MRI. In May, for even this to happen, just want to understand.
Hi pigpen, thanks, I am finding the new site quite difficult too! Couldn’t log in for 3 weeks, but they sorted it quickly once I emailed…
I should have said I am undiagnosed, so no Ms nurse. I posted here (which was naughty I know) because I thought there would be more chance of someone knowing the answer.
I think I may have worked it out - been googling loads! I had a Marcus Gunn pupil (RAPD) which is an objective sign that is hard to ignore or dismiss as nothing. The most common reason for it is ON, but can also be a sign of severe retinal disorders. Some of those tests are apparently to look for retinal disorders, so I guess in the light of a negative VEP, and with the other symptoms/ signs they are trying to find out if there is another cause for the rapd. Which is also why they are repeating the vep I expect
got a horrible feeling an appointment letter for a lumbar puncture may be on its way too.
However it seems whatever the reasons for the tests, I am being taken seriously, and investigated thoroughly which is half the battle!
Sounds as though they are doing all that’s necessary. I haven’t had a Lumbar Puncture but plenty of people on here say they are not as bad as expected. Someone will tell you about them.
Electrooculogram is concerned with the movements of the eyeball (up-down and right-left)
Electroretinography and Pattern Electroretinogram are concerned with the function of the cells in the retina. There are several layers of these, (arranged like a diagram of a “neural net”), and apart from handling movement and colour, they also enable us to detect the shapes of letters (and similar things).
Human vision is a wonderful subject (and more complex than it looks). Sorry, could not resist that one.
Thanks for your reply, that was really helpful, despite a rather unhealthy level of googling, I had not picked up on the eye movements thing! I must admit, I am pretty good at understanding medical jargon on websites papers etc, but the electrophysiology of the eye is so complicated I ahve struggled to understand!
Can I just ask what you meant by me getting close - do you mean inreference to my ideas on why they ordered these tests or do you meant to a Dx?
Limbo makes you clutch at straws a bit doesn’t it!
What I meant by getting close was that you were near to finding out what the tests are for.
But the other meaning could apply: a string of tests could mean that they think they have narrowed the Dx down (or it could be the “shotgun” approach (run enough tests and something might turn up).
I would go for the narrowing down situation myself. So much of neurology seems to be trying to distinguish between one condition and another, and it can take a lot of testing to make the last step. Like - your Marcus Gunn pupil could be down to the optic nerve just behind the eyeball, or a problem with the retina itself. Finding out where could determin how they treat you next.
