Evoked Potentials - what a shocker

Wow… I tootled along for evoked potentials today thinking it would be a stroll in the park and I was shocked how difficult, painful and tiring it was.

The visual part disorientated me and kept getting stopped so I could “concentrate” my eyes were running and smarting and it went on and on.

The nerve conduction up the limb was so much more painful than EMG/NCS quite excruciating… and kept getting repeated until I was fit to scream.

The hearing part was probably the least tortuous part…I’m not usually a cry baby but I found it on a par with giving birth.

I’m in a boat load of pain so I’m dosing up and getting horizontal to recover…I’ve searched to see if anyone else found the tests distressing but nothing really found…

has anyone else found Evoked POtential testing to be so painful?

No info given by the lady that did testing … I keep thinking that if I get a normal result god help anyone else who is properly ill??

Hi anon, I had them done last June and I found exactly the same thing as you. I found the visual one very tiring, the listening one OK, but the nerve conduction one was awful. It was really painful and seemed to last forever. The guy who did it had to turn it up so high in order to get my toe to react right from the start. It was not straightforward as I was led to believe. Teresa xx

Hi Anon x

Sounds like an utter mare!!! I’ve never had it done so can’t comment! Hope it all turns out well for you xxxjenxxx

Oh, I’ve only had the visual ones, not the rest. Whilst I didn’t find them painful, I couldn’t believe how long it went on (over an hour, I think), and yes, I did get tired. Also I had a terrible cold and sore throat on the day, and had to take a cup of water in with me. Which, inevitably, I forgot about, and spilt! I don’t think the operators were very pleased with me. I also questioned the technical integrity of the whole thing, because, a couple of times, some of the electrodes fell off, but nobody seemed to notice or care. As they don’t stay in the room with you, there was nobody to tell, so I had to wait 'til they came back in, and say: “The electrodes have fallen off!”. If they had been monitoring properly, wouldn’t they have been able to tell this? And what happens to the results when some of the electrodes were missing? I wasn’t altogether surprised when the results came back “normal”, even though I was subsequently diagnosed with MS. I can’t help wondering if “normal” meant: “normal for wet carpet”, which is where some of the electrodes were, at least part of the time! Tina


Not sure why I came up anon…but thanks Teresa you made me laugh (much needed) yes they had to crank the flamin voltage sky high to get my toe twitching. I can see the funny side of it now but I really wanted to rip the pads off and go home but I’m too controlled and polite to give in to such temptation

Tina…wow my technician never left me, I think she knew if she had I would have ripped off the eye patch and turned the tv off. I have to say I was not left alone at any point in the testing. See… I shouldn’t be complaining, I probably got the most efficient person EVER.

Keep posting stories it’s good to chuckle xx

Hi - I found the nerve ones very painful indeed and they also had to turn it up really high just to get even a little twitch out of my left little toe. No other left toes responded - yet the results were still normal.

Hope your results are ok too! x

I too found them to be extremely difficult so I can really sympathise. I hope you are resting and feeling better than you were. At least it is over and done with now and can be one step nearer to finding what is going on with your body. For me, the visual ones kept making me feel sick and I eventually had to rip the leads off my head and run and throw up…I would think a slightly odd sight to others in the waiting room who saw me run past with my hand clamped over my mouth and a couple of wires dangling behind me

I only had my arms done for some reason but like you, he had to turn it up so much it was excruciating but yet my thumb would only move on it’s own, not when the guy was attempting to make it do so. He had be lying in all sorts of odd positions in the hope that I could relax something or other and stop my neck twitching on it’s own too.

I hope the results come back soon.


It seems paradoxical in some ways. My left foot had the dial at 18 before I could even feel it and before a twitch (right foot was responsive at 4). There was some discomfort once underway. The tester, troubled by the need to keep turning up the dial put the electrode against her own skin to check it was working properly and there was the sound of a static spark and I thought I saw a puff of smoke whilst she exclaimed “Well its certainly working!” Whole process had me thinking of being connected up to ‘Old Sparkey’ with visions of household lights dimming throughout the neighbourhood, and the bit in Frankenstein where they restore the monster to life with lightening. Dont know the result of my test yet. I have found a couple of reasons for needing a high setting; one is edema in the affected limb which can cause short circuiting and the other is peripheral nerve damage in the affected limb e.g. from diabetes. I assume another reason may be poor positioning and conductance through the electrode if not done skillfully. Have not been able to establish whether MS can also be responsible, but the purpose of the test is actually to detect whether there is interference or blocking of a particular kind of brain wave, characteristic of when a lesion affects signal transmission along one particular side of the spinal cord (cannot remember whether the dorsal or ventral side). Of course there could still be a lesion in the cord on the other side but this test would not detect it. I guess the reason these results can still be reported back as normal even with the high setting, is because once this overcomes the peripheral obstruction, the signalling is able to traverse the cord unimpeded if it does not meet a cord lesion on the relevant side. However, there is the issue of what is causing the peripheral obstruction.

Thanks Guys,

Mrbbobowen you capture what I failed to be able to express perfectly. I think you have literary alent!

In our modern era of hi-tec it was indeed reminiscent of the frankenstein scene, I can’t help but think that a collection of stories from people such as ourselves should be gathered for all the different tests that one has to go through during diagnosis.

It’s ok reading about the test in a leaflet beforehand but that is purely the mechanics of how the test is done. Personally I would have preferred to know that I might find it difficult. I’m not talking about scare mongering people, just a realistic idea of the variations oh how different people react to the different tests.

Comments appreciated folks, Gill

Ooops Mr Bobowen you have creative literary “talent” I meant to say.

Why thanks Gill (blushing). Agree it is useful to find out about other people’s experiences of these tests. I am curious to hear what other people have heard from their neuro in relation to why it was necessary to resort to much higher voltages than usual, or much higher in relation to that needed to test the other limb. Anybody been given an explanation for this relating to themselves?

Know I am resurrecting really old post but… OMG! Had mine today. Visual a bit dizzy making, wrists quite uncomfortable but the ankle zaps were bad bad bad. He had to crank it up much higher on my left foot as my toes wouldn’t twitch even though I could feel it in my ankle soooo strongly. OH thought I was going to explode. Was writhing about in agony and he did that side for longer too. I also wondered if this points to a problem in my foot itself causing numbness etc rather than central nervous system. Would be really interested if anyone has found out what causes the need for higher cranking. I get that they need to make sure the signal is strong enough but what causes non toe twitching when you know they should be wiggling like crazy??? Cx

Claire I suffered in exactly the same way as you. The visual wasn’t too bad but the electric shocks were vile! My left toe would not twitch so the guy had to turn it up really high. OMG it was so painful - like torture I thought! I presume that the nerve damage is worse on that side so they need to turn it up higher in order to get the same reaction as you would on the other side when it is turned down lower. Or some such thing! Teresa xx

Ironically I read this yesterday morning, before leaving to have what I thought was just VEP’s done, and thought, ‘thank goodness i’m not having all that done’. But following the VEP, which also made me feel really nauseous, they decided to do the full set, hearing, hands, feet, and and a repeat set of VEP’s with a little electrode wire placed inside/under my bottom eyelids!!! Yuck! What should have been a 45 minute appointment turned into over a 2 1/2 hour marathon.

Anyway, it all dragged on a bit, and it was also my left toe/leg that was most reluctant to perform. However, later in the day, I got terrible shooting pains and my leg kept giving way, and I’ve had a banging headache, nausea and fizzing legs since tea time yesterday. Thank goodness I didn’t drive myself there, as I don’t think I could have driven the fifty miles home.

Hi Hunny It’s horrible isn’t it? Akin to torture I feel. They try to make little of it and make out it is routine but I hated it. It was far worse than my LP which was no problem at all. Teresa xx

Hi Teresa,

Yes it is horrible. I was totally unprepared for it really. I know ignorance can be bliss, but I’d always rather know what I was facing and prepare myself for it, than be caught off guard. Its my son’s 16th birthday today, and I’m wiped out. If I’d known it was going to be that intensive, I think I would have rescheduled. The tests. Not the birthday!

I hope you’re doing OK? I know you’ve had a bit of a rough time of it lately xx

Thanks Hunny - yes things have been rough lately but I think my life is about to change for the good! A continence nurse showed me ISC today and I found that it was nowhere near as tough as I thought. I think this will revolutionize my life and that I will feel like a person again not just a thing! Sorry you’re feeling so wiped out tonight, especially on your son’s 16th birthday! Btw I have one too (a 16-year-old son that is) but his birthday is July so he is the year above yours! Give yourself some tlc - you need it and take care! Teresa xx

I just had evoked potentials for my arms and legs for neuropathy. The most painful test ever!!! I cried in agony until it was done. My hands and feet were on fire afterwards with tremors. Had a headache and was extremely thirsty. None of the sites I looked at describing E.P. said anything about pain. Wow! Won’t do that again any time soon.

Had mine done yesterday and my feet and hands still feel tingly and quite sore! It was so [removed by moderator] painful. A very good torture technique!! I thought it was bad enough when she tested my hands but I was not prepared for the immense pain while testing my feet. Apparently they need 2 good runs, as she put it. Since neither big toe wanted to co operate she turned it up, then up then up. Eventually there was the slightest twitch and she ran the test with that. I was led to believe there may be some tingling and mild discomfort! Wrong. It was extremely painful and 2.5 hours of it felt like forever!