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Fibromyalgia Action UK
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Evoked potential test- what can I expect?

Hi All,

Hope you are having as good a day as possible.

My neurologist is sending me to a different hospital (4th one now) for an Evoked potential test - does anyone know what this is and what it might involve?

DO I need to take anything or is it better not to take some of my meds?

They have not discussed it with me - just got a call telling me it is booked and the date so a bit in the dark.

Hope someone can enlighten me :-)

Big gentle Hugs,


8 Replies

I think I had this done several years ago and was told that I was super human on the way my body transmitted pain but the important thing for me to say is it did not hurt at all. So don't worry about it. The 'pain' only has to be very mild for the test to work. I would ask about meds and what you should wear.


Hello Mrs_Somerset,

Please can I provide you with this link;


Usually with tests you'll receive a letter with all information about what information to bring with you. I've never had this test but others may have.

Our volunteer ken will be able to shed more light as his wife has MS so I imagine they have been to these studies

Best Wishes

Emma :)

FibroAction Administrator


Hi, I would just do as usual. I think the test will involve putting electrodes onto your scalp in order to see whether the nerves are transmitting properly, that's all. Probably the only thing will be that you may want to wash your hair that evening.


Hi Mrs_Somerset

Please do not be worried by this test, it is a very straight forward measurement of electrical activity in the brain. The 'flow' can be altered, diverted or interrupted which can cause mobility and flexibility issues. The test is not a full indicator of MS as this can only be achieved by an MRI of the brain, whereby the myelin layer will show multiple lesions if a person has MS.

What they are probably looking for is what they term ' a singular event' this is where myelin may not be badly damaged and only a single lesion appears on the brain. This is NOT MS! So please do not torture yourself with worry! If a singular event is recorded then this should recover by itself but they may prescribe some medication. If they decide there is an issue to explore further they will most likely send you for an MRI of the brain and upper spinal column, and this will determine any diagnosis of MS.

Please remember that there are 3 categories of MS, and the vast majority of sufferers have what is called relapsing remitting, I have pasted you a section from the NHS Choices pages on the types of MS:

Types of multiple sclerosis

Around eight out of 10 people with MS are diagnosed with the relapsing remitting type of MS.

Someone with relapsing remitting MS will have flare-ups of symptoms, known as relapses. These can last from a few days to a few months.

These will be followed by periods where symptoms are mild or disappear altogether. This is known as remission and can last for days, weeks or sometimes months.

Usually after around 15 years, around half of people with relapsing remitting MS will go on to develop secondary progressive MS.

In secondary progressive MS, symptoms gradually worsen over time. Some people may still have relapses, but without full recovery from symptoms.

The least common form of MS is primary progressive MS. In this type, symptoms gradually get worse over time and there are no periods of remission.

This is the link for this page:


My wife has Primary Progressive MS which is the very worst kind. It is not a common category, and the chances of you having this are extremely slim! As sufferers are wheelchair bound.

I want to wish you all the best of luck with your scan and please let us all know how you get on?

All my hopes and dreams for you

Ken x


Hi Ken,

Thank-you very much for this info - very useful,


I have already had a brain MRI - they said all was fine ( they did not say what they were looking for though)

They have already ruled out MS

So, as usual, totally int he dark as to why they are doing this new test - I only get to speak to the people who are calling me to tell me about the appointment - tey have no idea why it is being booked either = this is the same for most of my tests over the last year - so I seek info from you guys on HU - a trusted source of useful info.

one of my friends husband has what I now assume to be progressive MS, he is currently in a wheelchair using a mouth operated device to type - this progression has taken place over the last 9 years from fully fit, to fully dependent upon his wife ( my freind) , I was unaware there were different types, which explains why my optician, who said she has MS - seems perfectly fine and capable :-)

Always a font of wonderful info Ken :-)

Big Hugs,


1 like

Hi Mrs_Somerset

I am rather puzzled as well? It may be best to ring them and discuss what it is for? I want to wish you all the best of luck and I genuinely hope that it all goes well for you.

I am so sorry to read that you have friends with MS, and I genuinely hope that they are as pain and as stress free as is possible.

All my hopes and dreams for you

Ken x


Hi, I recently had evoked potential test. U will need to phone them to check about taking meds, but otherwise I had to go in loose comfortable clothing & had to have freshly washed (but dry) hair, as this helps the electrodes to stick to your scalp.

I had 3 types of evoked potential test - sight, sound & touch. Whole process took 1 1/2 hrs. I'm still eating for results at end august.

First I went into a room and was sat down in a recliner chair in front of a TV screen. They attached the electrodes to scalp (painless) and I then had to watch patterns on the screen (one eye at a time, the other covered), whilst trying not to blink too much. Next I was laid back in the chair, close eyes & headphones put on whilst they played white noise and clicking sounds in one ear at a time. Finally they attached electrodes to my ankles - like TENS machine or the muscle toning belts u can get. One side at a time they turned it up slowly until my foot twitched slightly & recorded brain activity for this as well.

The hardest part was trying to sit still for so long (although I did find the electrodes on one ankle painful & nurse commented that this never hurts anyone & I must have a very low pain threshold !!!!!).

Good luck & hope that helps xxx

1 like

Hi agtf1,

Thank-you very much for this info - very useful - so far I have had no info from the hospital just time and date and the name of the hospital.

I will need to ask them about meds I think, as I am on a lot at the moment :-)

Big Hugs,



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