Neurology
Strong Epilepsy Center
Tests - Intracarotid Amobarbital Procedure (IAP)
What is the IAP or "WADA Test?"
The purpose of the IAP (Intracarotid Amobarbital Procedure) is to find out where speech and memory reside in an individual's brain. The test is designed to evaluate each side of the brain separately. The results of your test are carefully analyzed to see how each side of your brain responded. This information will guide the Neurosurgeon in planning your surgery. Our goal is to eliminate your seizures without affecting your speech or memory.
How Do You Prepare For The Test?
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Most patients are asked to come to the hospital the day before the test for a Neuropsychological Evaluation, a practice session, lab work and a physical exam by a nurse practitioner.
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The purpose of the practice session with the neuropsychologist is to be sure you are familiar with the procedure. If the patient is a child, one parent must be present during the practice session in order to help the child understand the procedure. If the patient is a child or is unable to provide informed consent, a parent or legal guardian must be with the patient on the morning of the test to provide informed consent.
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You should not eat anything after midnight the evening before your test. You may drink clear liquids, such as water, but do not drink liquids like orange juice after midnight.
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If you normally take your regular medications in the morning, you should take them the morning of the procedure with just a sip of water. DO NOT take aspirin the morning of your procedure. If you take a blood thinner such as Coumadin (Warfarin) or Luvenox (Enoxaparin) notify your doctor as soon as you receive these instructions for further directions.
What Happens During The Test?
The IAP is done in two parts.
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The first part is called an angiogram.A thin, plastic tube is inserted into an artery at the top of your right leg (this is called a catheter), after this area has been numbed with novocaine. Then, the tube is moved up through your body. You should only feel mild pressure at the insertion site. A dye is injected through the tube and into the carotid artery. This dye makes it possible for the doctors to take pictures of the blood vessels in your brain. Both sides of your brain will be x-rayed by the radiologist.
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In the second part, a medication, sodium amobarbital, is injected into the carotid artery through the tube in your leg.Sodium amobarbital is a short-acting sedative. It is directed to one side of your brain and will numb that side of your brain. You will be asked to perform simple tasks, such as naming objects, reading a short sentence, or recalling objects. This procedure evaluates the functions on the side of your brain that remains active. After the effects of the sedation have worn off, the catheter will be moved to the other side and the procedure will be repeated. The catheter is moved inside your body, so it is only placed once, in your right leg. Again, the neuropsychologist will ask you to perform the same simple tasks. Some patients feel groggy, weak or confused immediately after the injection of the sedative. It usually takes some effort to focus on the task, but the material presented to you will be simple and you will be familiar with the procedure from the practice session. You should do your best to follow directions, but this is not a "pass" or "fail" test. The doctors are interested in analyzing and comparing the responses from the two separate sides of your brain. You should not worry about how well you perform.