Abnormal Evoked Potential Testing?

[ashleyPT]

I've been searching articles and asking doctors without much luck so now I will ask you guys with all of your experience.  I had abnormal sensory evoked potential testing: when my left tibial nerve was stimulated the signal is normal until it gets into the cortex and then it becomes absent.  When I asked what diagnoses can have those results my neuro told me MS and sometimes tumors (I have normal MRIs). At least 90% of resources talk about this test only to diagnose MS. The other uses for this test don't really apply to me from what I've read (comatose patients, monitor surgery, and disc herniations)

Do you guys know any other diagnoses that can have abnormal evoked potentials?  I asked the neuro if there could have been a mistake during testing and she assured me that the test was re-done multiple times to make sure it was not a false positive.

[Lulu54]

I have not had any evoked potential testing done, but there are certainly plenty here who have experienced this test.  I went searching for other causes out on the web and find vague references but nothing specific.

Here's hoping someone will be able to answer you question.

my best, Lulu

[PastorDan]

Sorry, but the only evoked potential test I've been through to-date is the brainstem auditory, where you just listen to clicking.  They said that was fine.  I'm not yet diagnosed, either, so I'm not sure I can tell you much from that.

[Quixotic1]

I think the words of a Neurology Forum Expert sums up when you can see abnormal evoked potentials best:

http://www.medhelp.org/forums/neuro/messages/30149.html

He/she states:

"ANYTHING which interferes with the function of the nerve fibers will cause an abnormal test result. The test only proves that there is some  problem, somewhere but it is not at all specific as to the identity of the underlying disease. becuuse of this the test must be interpreted in context, that is in the context of your symptoms, the findings on physical examination and the results of other supportive tests like the spinal tap and MRI."


I did a little bit of noodling around to get some examples.  Things like acute viral encephalitis, acute cerebellar ataxia, Acute Disseminated EncephaloMyelitis (ADEM), tumors (benign and malignant), Systemic Lupus Erythematosis (SLE or Lupus), likely any rheumatologic disease that can cause a cerebritis (brain inflammation).  It's late at night so that is where I stopped.

So, I found that any thing that damages the nerves of the central nervous system can cause abnormal (slowed) evoked potential results.  

Yes, this test is often used when trying to nail down MS, but it is not nearly sensitive or specific enough to be a defining test for MS.

Of the things I listed, Lupus and ADEM are really on the list of mimics of MS.  As far as severe B12 deficiency, or things like Lyme Disease or HIV, or Wilson's Disease etc., I don't know.  Would have to look them up.

Welcome to our forum.  Why don't you tell us what led to your having the sensory evoked potential?  We have a lot of people with great experience and information here.

Quix

[shoshin]

When I had an abnormal SSEP, the only thing the neuro concluded was that I had a problem with the central nervous system. He did start talking about MS, but I was also tested for Devic's/NMO and Sjogren's after this, plus some bloodwork, so it apparently didn't rule those other things out.

sho

[ashleyPT]

I've had extensive bloodwork, multiple MRIs over the past few years, and after the evoked potential test I had a LP - which was normal.  I started with foot drop over 3 years ago.  Each summer since then I seem to have a period where my symptoms are very bad and getting worse and then I slowly recover, but have never recovered all the way.  At first, I would get foot drop for 3 days then take a couple of weeks to recover.  I've probably had 6-8 episodes of muscle weakness in the left leg.  The latest episode was july 08 I couldn't move my left leg at all.  It took about a month to start improving, but then I got sick and had a fever for a few days in October and it put me back to how weak I was in July.  I am just now getting my strength back in my left leg.  I also have numbness in tingling throughout my left side.  I've started having pretty severe left arm weakness (muscle atrophy, dropping anything I pick up with my left hand).  I can't feel pain and temp in my left leg, and now I have a large patch on my upper left back and shoulder that I can't feel.  I have some other symptoms too - like blurry vision, and some abnormal pupil reflexes.