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Wada Test Patient Information Leaflet (Neurophysiology Department)

Your consultant would like you to have a Wada test.

What is a Wada test?

This test helps your doctors to discover which side of your brain controls speech and memory prior to you being considered for epilepsy surgery. A Clinical Physiologist will perform the test and staff in training may be present during your investigation, this will be explained at the time of your appointment and consent for this will be discussed with you.

What should I do before the test?

Wash your hair and do not use hair products (ie, gel or hairspray). Take your medication as normal unless otherwise directed by your doctor. You will be admitted onto the ward the day before the test and meet members of the Neuropsychology department who will explain their part of the procedure to you. Your consent for the procedure will be obtained. You will not be allowed breakfast or lunch on the day of the test.

What will happen during the test?

You will be brought to the Neurophysiology department where small electrodes will be placed onto your scalp and a medical glue is used to hold them in position. A short EEG recording will be undertaken for about 10-15 minutes during which time you will be asked to open/close your eyes. This is not painful. You will then be taken down to Neuroradiology where an angiogram is performed by a Radiologist.You will be asked to get onto a special bed and will be covered in sterile sheets (a nurse may need to shave a small area of your groin). The first part of the test involves a small catheter being put into an artery in your groin, following a local anaesthetic injection and a special dye is then injected. This dye helps all the blood vessels show up on the X-ray. Once everything is prepared the Neuropsychologist will ask you to raise your arms in the air and start counting, your EEG is recorded throughout the investigation. We will ask for your consent as in addition we record video. The drug (Sodium Amytal) is then injected through the catheter. You maybe aware of a warm sensation in your face, or that one of your arms becomes weak and starts to drop, this is a normal reaction to the drug and will not be permanent. The Neuropsychologist will ask you several questions to test your speech and memory following the injection of the drug.

As the drug effect wears off you will be left to rest quietly for 10-15 minutes. The Neuropsychologist will then ask what you can remember from the test period. After a 40-45 minute rest the same procedure is then undertaken testing the other side of your brain.

How will the results assist my Consultant?

This test will help to discover which side of your brain controls both speech and memory. This is an important consideration if you are thought to be suitable to have surgery to help control your epilepsy.

Are there any risks?

There is a 1-2% chance of a brain haemorrhage during the procedure. This could result in temporary or permanent incapacity, such as stroke. There is a small chance that you may have a reaction to the drug and experience shivering, this does not last long.

Is the investigation painful?

There may be some discomfort when the local anaesthesia in your groin is first given

How long will the test take?

The whole procedure will take between 3-4 hours.

What happens after the test?

Once the test is completed the Clinical physiologist will remove the glue and electrodes from your hair (You may wish to bring shampoo with you to use after the investigation). The catheter will be removed from your groin and pressure applied to that area for 15 minutes, this helps stop any bleeding. On return to the ward you will be required to lie flat for a number of hours. You should be able to go home the following day.

What are the consequences of not having the Wada test?

The consultant will be unable to determine which side of your brain controls your speech and memory. The consultant will not have as complete a picture as they require to decide whether or not you are suitable to undergo surgery to try and control your seizures.


If for any reason you are unable to make this appointment or have any specific requirements or questions (before or after the investigation) please ring 0151 556 3416.

We can provide this information leaflet in larger fonts or audio format via email if required, please phone the number above.

This information can be translated on request or if preferred an interpreter can be arranged for additional information regarding these services please contact the Patient Experience Team on 0151 556 3090.

  • Last Updated:
    03 October 2022
  • Review Date:
    03 October 2026
  • Author:
    Beverley Haworth & Natalie Gore
  • Summary:

    This test helps your doctors to discover which side of your brain controls speech and memory prior to you being considered for epilepsy surgery. 

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