Wada (Intracarotid sodium amytal) test
The Wada Test is used to determine the side of the brain responsible for language and to assess how much of a patient’s memory is supported by each side of the brain. This is performed in most patients where temporal lobe surgery is proposed. The Wada test can help determine the amount of memory reserve on the “good” side of the brain. This is needed because part of the temporal lobe is an integral component of the memory function, but is routinely removed during temporal lobe epilepsy surgery. In these cases, having adequate memory reserve on the brain’s opposite temporal lobe is reassuring that the patient will not develop devastating memory difficulty following surgery.
On the day of the test, the patient is admitted to the Ambulatory Treatment Unit (ATU) at Harper University Hospital. This requires a hospital stay from early morning to mid afternoon. During this test, a very short-acting anesthetic medication (sodium amobarbital or amytal) is injected into the blood stream going to the brain, in order to temporarily put half of the brain to sleep. The Wada test helps neurosurgeons know if epilepsy surgery will produce lasting deficits to the patient’s speech or memory.
As part of the test, a thin catheter is inserted into the artery in the right groin region and then threaded up to the carotid artery in the patient’s neck. A dye is injected into the catheter to help visualize the blood vessels of the head. After this, medication is delivered into the catheter to put half of the brain to sleep. At this point, patients sometimes find that one side of their body is weak or that they have trouble speaking. This is a temporary effect, which resolves as the medication is removed from the blood. During the test, the epilepsy team asks the patient several questions to evaluate language function and asks the patient to remember certain objects. After about 30 minutes, which is the time it may take to fully recover from the medicine, the epilepsy team injects the medicine into the other side of the brain and repeats the testing. During the entire test, EEG is monitored to study effects of the medication on the brain. The EEG is performed using scalp electrodes only.
Electrocorticography and Cortical Stimulation
Essentially, this is intracranial brain mapping performed either in the operating room or over a longer period of time with surgically implanted electrodes. Fortunately, advances in neuro-imaging have reduced the need for intracranial monitoring. But, when necessary, electrodes applied directly to the cerebral cortex can be a valuable diagnostic tool for identifying the motor, sensory, language, and visual parts of the brain as well as the areas of the brain causing seizures. By mapping these areas, epilepsy surgery can be performed with a high margin of functional safety.
Quantitative EEG (qEEG)
Intracranial EEG recorded with the help of depth or subdural electrodes can be analyzed using powerful quantitative techniques to learn more about the interaction of EEG changes at the time of seizures and in between seizures known as interictal abnormalities. Our physicians and researchers are at the forefront of these techniques and are actively engaged in research funded by the National Institutes of Health (NIH). Combining information from advanced imaging techniques and qEEG in a composite 3D image provides an even more powerful tool clinically and helps researchers advance our understanding of epilepsy.
The Comprehensive Epilepsy Program combines structural neuroimaging studies such as MRI with various functional imaging studies and electrophysiological data. This approach provides precise knowledge of where the seizure is starting and where important neurological functions are located — providing the best possible chance for excellent outcomes following epilepsy surgery.
In addition, researchers at the WSU School of Medicine provide a depth of knowledge and cutting-edge technologies to advance our scientific knowledge of epilepsy. The epilepsy research team at WSU includes:
- Neuromiaging specialists
- Computer science experts
- Research nurses
- Research assistants
- Graduate students
They use advanced structural and functional neuroimaging techniques such as MRS, PET scanning with various ligands, advanced electrophysiology techniques and multimodal imaging to understand the molecular mechanisms of seizure onset, interictal epileptiform activity and the role of inflammation in epilepsy.