For epilepsy surgery candidates, an intracarotid sodium amobarbital procedure (Wada) may be ordered after an EEG and before surgery.
Both the left and right side of the brain control memory. The left side of the Brain often controls the ability to listen and speak, however this is not always the case. Research tells us that individuals with abnormalities in brain development may have atypical organization of cognitive functions, which can make it difficult to predict where certain skills are located in the brain. Because of these issues, the epilepsy team will sometimes recommend that a child undergo a Wada test to determine which cerebral hemisphere controls language and memory function. The goal of the Wada is therefore to identify the side of the brain that has stronger mastery of those skills.
The results of the test has to be taken into consideration during the planning process for surgery.
For example, if a child’s seizures are originating from the right side of the brain, which is also the side of the brain with stronger language and memory skills, additional testing may be required to ensure that neurosurgeons map the safest path into the brain before surgery.
Before WADA
Wada tests (or intracarotid amobarbital studies) are conducted by the neuropsychologist, epileptologist and neuro-interventionalist. Prior to the procedure, you and your child will meet with the neuropsychologist to review the details of the test and rehearse how the test will be conducted. This serves to prepare your child for the procedure, and it allows the neuropsychologist to establish your child’s baseline level of functioning. Only children that can participate and are of a specific maturity can participate.
During the WADA
On the day of the Wada test, the neuro-interventionalist will perform an angiogram on your child, which requires the insertion of a catheter into the femoral artery. The catheter is subsequently maneuvered through the vascular system until it reaches one of the internal carotid arteries. Once your child is ready, a short-acting anesthetic is released into the internal carotid artery that essentially puts to sleep one half of your child’s brain for a period of 3 to 4 minutes. During this time, the epileptologist monitors the EEG to ensure that the anesthetic has the desired effect, and the neuropsychologist presents stimuli to your child, such as pictures, words, and objects. After the anesthetic wears off, the neuropsychologist test for Memory and Language by asking your child to remember object shown and to name objects or read sentences. This will be repeated on the other side after the initial side of the Brain is fully awake.
The test usually lasts approximately 30-60 minutes.
After WADA
Your child will be on bed rest with bathroom privileges for several hours in the hospital. The nurses and doctors will be checking the pulses in the leg where the catheter was inserted and will also check under the dressing.
The concept of an Epilepsy Passport should be considered as with UK child health as with the example below:
