University of Washington Regional Epilepsy Center at Harborview Medical Center

The intra-carotid amobarbital "Wada" test is performed primarily on epilepsy surgical candidates to determine which side of the brain speech, memory, and motor functions reside. The Wada decides if a patient can be sedated during brain surgery or must be awake in order to have cognitive testing during surgery. The cognitive testing pinpoints the precise areas of the brain associated with speech and memory.

The patient is settled in a neuro-angiography suite and under no sedative, a catheter is placed in the femoral artery and guided to either the left or right side of the brain. A dye is injected into the catheter which allows the radiologist to view either side of the brain in the search for abnormalities, particularly of a vascular nature.

Dr. Carl Dodrill, neuropsychologist, screens the patient's responses before amobarbital is injected into the catheter. Here he asks the patient to raise both hands and point all ten fingers to the ceiling while naming objects in front of the patient's view.

Once Dr. Dodrill feels he has enough information to proceed, he advises the radiologist to inject 100 mg of amobarbital into the catheter which puts the left side of the patient's brain to sleep. This causes the right hand of the patient to drop and indicates the patient's left hemisphere has been adequately anesthetized. He then asks the patient to name objects.

On the picture to the right, Dr. Dodrill asks the patient to read from a card.

The neuropsychometrist scores the patient's responses. After the Wada is completed, she compiles the data obtained from the score sheet. A determination will be made by the physicians on how they will proceed with surgery using this data.

After a few minutes, the amobarbital wears off and the left hemisphere of this patient's brain "wakes up". Dr. Dodrill encourages and praises the patient after the first half of the Wada is completed.

The catheter is repositioned in the right side of the brain and dye is again injected into the catheter. X-rays are taken of the right side of the brain and once x-rays have been reviewed, amobarbital is again injected into the catheter. Dr. Dodrill repeats the steps in phase 1.

The patient's left hand falls as the right side of the brain is put to sleep. Objects are shown to the patient. The patient is asked to read a card and then is asked to recall the word.

The test is almost completed. The patient's right brain has woken up and she now can follow instructions, name objects correctly, read cards accurately and recall objects.