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Abnormal Evoked Potentials
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Abnormal Evoked Potentials

I have had the following symptoms over the course of the last year and a half:  burning in left calf muscle, 2 weeks of legs feeling heavy and stiff to bend, tingling in hands and feet, systemic tingling (a tingle here, a tingle there), buzzing, widespread twitching, a fine tremor in my hands, feet hurt off and on like there is no padding on heels.  The twitching and tingling remain. I am still strong and run 4 miles a day.

Three months into this I had normal C-Spine MRI, Brain MRI and Spinal Tap.  Two months ago I had a NCV test which showed what my neurologist called borderline sensory nerve damage in my left leg but felt it was "something I was born with".  I recently went to a different neurologist who said he suspected MS not Peripheral Neuropathy because my symptoms didn't match up for PN. He said sometimes all tests for MS can come back negative early on in the disease.  I had a Evoked Potentials and a Somatasensory (?) Potential Test.  He called me last night and said my Evoked Potential Test was abnormal and indicative of demylination. I am so confused, frustrated and frightened.  Can a Spinal Tap come back normal if it's early on in the disease and EP pick up lesions? After all those intial tests came back normal,  virtually every doctor I have gone to has assured me MS is a very REMOTE possiblity and told me I have anxiety issues.

How reliable are EP?  I can't obviously ask my neuro this as he obviously strongly belives in the test.  Are there other things that can casue abnormal Evoked Potentials?  I was bit by 5 deer tick three years ago.  Can Lyme disease cause this although I have had a negative ELISA and Western Blot?
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Avatar_n_tn
An evoked potential test is really a test of the " traffic " in the nerve fibers from the periphery to the brain.
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.
Given that all of the other tests are negative I would agree that MS is a remote possibility, there is certainly not enough information available at this stage to make that call. I would not think that Lyme isease is a realistic possibility either, the underlying cause of this abnormal test may not be identifiable.
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Avatar_n_tn
I can not thank you enough for responding.  You have really helped calm my fears and put this one test in perspective.  I have another question that I hope you won't mind answering.  You said that a visual Evoked Potential tracks the transmission from the peripheral nerve to the brain.  Could there then be a Peripheral Neuropathy causing the problem.  Can you distinguish this at all on the test?  I am just curious whether a neuropathy like CIDP could also cause the problem. Thanks again.
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Avatar_n_tn
I feel for Lori in that I have had similar symptoms for the past 2 years now, with no answer as to the cause.  Burning, tingling, muscle soreness/stiffness, twitching and joint pain all over the body for me.  All my tests to date have come back normal and  meds the doctors have tried (Elavil and now Celebrex, a non-steriodal, anti-inflammatory) help somewhat but not completely.  Nothing has really changed for me.  Doctors have said (and I've been to them all) that it sounds like I have Fibromyalgia.  I wish I had something more concrete than "sounds like", but I know they do the best they can.

I too have suspected Lyme because of a tick, but have also had negative blood tests for that.

Is Lyme at all possible even though blood tests are negative?  Have people been diagnosed and treated for Lyme without positive tests?

I just re-tested an MRI of the brain (and the lower spine this time, not cervical) and that continues to be normal after two years.  Can MS show up after years of symptoms and normal MRIs?  How often should an EMG be done if no diagnosis is yet found and symptoms persist?  (Had an EMG 2 years ago also and that was ok too).

Thanks for the info. very much, and Lori, hang in there, you are definitely NOT alone.
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Avatar_n_tn
I have also had very similar symptoms for over 2 years, and all tests (EMG, MRIs, spinal tap, clinical exam) were completely normal except the evoked potentials.  My neurologist suggested I see a neuromuscular specialist at a teaching hospital.  After a careful evaluation, he ruled out a progressive neurological disease.  He said he has other patients with similar symptoms and that they do not progress and become disabling.  This was very reassuring and really helped me learn to live with these symptoms.  Hope you too find some answers and peace of mind.
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Avatar_n_tn
Stephanie -

I am very interested in what your symptoms are.  You and Kim really helped me feel like I am not losing my mind here.  I take it your neurologist feels the abnormal EP was nothing to be overly concerned with?  I guess you had an EMG? Did your neurologist have any insight as to why your EP would be abnormal in light of your symptoms?  I twitch alot and have what I think is myokymia also.  I wonder if a disorder at the neuromuscular junction of a nerve would throw off the signals in a EP test.
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Lori,

My neurologist was not that concerned about the abnormal EP as all the other tests were completely normal.  She said that even disease free people can sometimes have some abnormality.  If you test someone this much you are liable to find something abnormal!  Also the abnormalities did not correlate that well with the symptoms I was having at that time.
I have very similar symptoms to what you describe.  I get buzzing sensations, twitching, and tremor in my hands which come and go.  My muscles on the right side also feel very fatigued from time to time.  I also had constant burning down the back of my legs and the bottoms of my feet for about 18 months.  Luckily I moved to a new town and my new doctor sent me to physical therapy.  They showed me how to stretch out tight muscles that were pressing on the sciatic nerves.  The burning is down significantly, and I can now even run some again, so I am very grateful for that.  I hope you find some answers and relief from your symptoms.  Don't give up.
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Avatar_n_tn
Thanks to all of you that are help reassuring me that I'm not losing my mind.  I have intermittent buzzing, tingling, weakness, stiffness on right side.  Started this past spring only lasting over several days.  Several other episodes lasting only several hours over the following months.  Then one month ago had a more prolonged "attack" with all of the symptoms present at once.  This has stayed with me for about 1 month but it comes and goes.  I've had a day or two with no symptoms at all.

All blood tests have come back normal.  Brain MRI was normal.  They diagnosed as depression/anxiety/stress which I have difficulty believing because 1) I don't feel any of these emotions and 2)past stressful situations have caused numerous headaches and Irritable Bowel Syndrome.  Haven't had this for years.

Neuro put me on antidepressants and seems certain there is nothing neurological.  I'm not so sure.  My question is how painful are these other tests (EEG, EMG, EP, Spinal Tap, etc.).  If I have something like MS that they can't do anything for anyway and tests may all come back normal since it is early, I'm not sure I want to go thru any "agony."  Especially since it may only turn up as more unanswered questions.  What do you think?  Should I press my neuro for more tests or not?
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Avatar_n_tn
Kim,
It is a really tough question.  As far as pain goes, they were not bad.  The EP and EMG are a little uncomfortable and tedious, because they take some time.  With the spinal tap, I felt some pressure but not really pain while they were doing it.  Emotionally though, you may really feel like you are going through the wringer having all these tests.  (But you probably already do!)  If your doctor recommends them, I would definitely have them.  They may well be normal, and you will gain some peace of mind.  Whether you should press for them or not is hard to say.  I had them gradually over many months.  The waiting was frustrating but I think necessary in my case.  Best of luck to you.
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Avatar_n_tn
Lori, though it has been a month since your last question, I can answer it. The somatosensory evoked potential can distinguish between a peripheral nerve vs central abnormality i.e spinal cord or brain in some cases.  It cannot provide detailed information on peripheral neuropathy as can an EMG/NCV.  A person can have an abnormal SEP with abnormalities in both peripheral and central conduction times.  The SEP cannot provide any information on the neuromuscular junction. The SEP is testing the nerve signal as it travels from the wrist or ankle to the brachial or lumbar plexus to the spinal cord to the thalamus to the cortex or surface of the brain. You also mentioned the Visual evoked potential which is a totally different test measuring the time it takes for the signal to travel from the retina of the eye to the back of the brain ( the primary visual cortex.) I hope this helps you or anyone else reading it.  I have been conducting these tests since the 1970's.
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