Evoked potential appointments


How to get an appointment

You can ask your hospital doctor to refer you.

Changing or cancelling your appointment

Phone: 020 7188 3954

Before your appointment

Before your test you can:

  • eat and drink as normal
  • take your usual medicines

Please make sure your hair is clean. Do not use hair products or wear hair extensions.

If you wear glasses or contact lenses, please bring them.

Let us know before your appointment if you have a cardiac pacemaker or any other implanted device. Please bring any information you have about your pacemaker or other devices when you come to your appointment.

Wear loose clothing to your appointment. 

Make sure your hair is clean and dry.

Please do not use:

  • moisturisers
  • body lotion
  • hair products

During your appointment

You'll see a clinical physiologist.

We're a teaching hospital. Sometimes students or other health professionals will be at your appointment to learn. We'll ask you if you're happy for them to be at your appointment. It will not affect your care if you prefer not to have them there.

The test takes between 30 and 60 minutes.

We ask you to read an eye chart to check your eyesight.

We then apply 7 small metal discs called electrodes onto your head with some sticky paste.

We cover one of your eyes with an eyepatch and dim the lights.

We ask you to focus intently on the centre of a television screen with a moving pattern of black and white squares on it. We test each eye separately for a few minutes at a time.

You may also need to look towards a flashing light, with each eye for a few minutes at a time.

Occasionally, we may need to put a very thin thread on your lower eyelid.

We'll explain these tests in more detail during your appointment if they are needed.

After the test, we remove the discs. You'll be able to go home or to work after the test.

The test takes between 60 and 90 minutes.

We record signals sent from your nerves and brain in response to physical stimulation. We apply small metal discs, called electrodes, on your:

  • arms
  • legs
  • back
  • neck
  • head

We ask you to relax on a reclined chair. You'll feel a tapping sensation while the nerve is being tested. It may feel slightly uncomfortable.

After the test, we remove the electrodes and wash your skin.

You can return home or go to work after the test. You can also drive after the test.

After your appointment

We'll send the results of your test to the person who referred you.

This usually takes 1 to 2 weeks. 

Please contact us if you have any problems.

Last updated: September 2023

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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