Evaluation for Epilepsy Surgery
In order to decide if epilepsy surgery can help you to control your seizures, we need to do a number of tests. These tests help us locate where in the brain seizures may be starting. They also tell us if any part of the brain is abnormal in other ways. We evaluate each person individually before we decide which tests you will need.
Diagnostic EMU Evaluation – We need to determine first whether or not your typical spells/events are truly epileptic seizures and if they are the right types of seizures for the epilepsy surgery.
Phase I Evaluation – If we think you should be evaluated for possible surgery to help control your seizures, we bring you into the hospital for another EMU evaluation with additional tests. Ultimately, we need to capture 3-5 seizures to ensure all of your seizures are coming from one focus. In addition, we conduct an ictal SPECT study during this admission.
SPECT Study – SPECT is a special type of brain scan. SPECT stands for Single Photon Emission Computed Tomography. A small amount of a radioactive isotope is given intravenously when the seizure occurs. This isotope goes to the part of the brain where the seizure is occurring. We often obtain inter-ictal SPECT for the baseline. This is a very safe test. This type of radioactivity only lasts a couple of hours in the body before it is eliminated. There are no special precautions after the injection.
MRI of Brain – High resolution MRI is performed to evaluate any structural abnormalities or lesions, which may be responsible for seizure foci.
Inter-ictal PET Scan – This special brain scan is similar to the SPECT scan. PET stands for Positron Emission Tomography. It is also very safe and usually conducted as an outpatient study. The scan reveals any functional abnormality in the brain.
Neuropsychological Testing – Neuropsychological tests show us how the different areas of the brain work. A neuropsychologist performs the tests in the office. The tests include thinking, problem solving, reading, visual identification, naming, other language function, memory, and movement. Testing helps identify areas where the patients may have problems, which are usually the areas where your seizures are happening. These tests may take several hours to complete so plan on getting a good night’s sleep and having a meal before coming.
Psychiatric Evaluation – Having epilepsy may cause many emotional problems for you and your family. In addition, many of anti-epileptic medications may cause emotional problems, such as depression and suicidal thought. Epilepsy surgery may result in many changes in your life. For this reason, a psychiatrist conducts an evaluation to assess the patient’s emotional readiness for epilepsy surgery and how much support they will receive after the procedure.
WADA Test and Angiogram – The WADA test is named after Dr. Juhn Wada. The test is conducted while the patient is awake. A barbiturate or other anesthetic medication is introduced into one of the internal carotid arteries via angiogram. The drug is injected into one hemisphere at a time in order to shut down temporarily any language and/or memory function in that hemisphere. The patient is engaged in a series of language and memory-related tests to understand which hemisphere support these functions.
Functional MRI – This specialized MRI helps to understand how the different areas of your brain work. It measures the hemodynamic response (change in blood flow) related to neural activity in the brain with various activities.
MEG – Magnetoencephalogram (MEG) is a record of magnetic fields, measured outside the head, produced by electrical activity within the brain. The magnetic fields are produced by the same underlying electrical changes that give rise to the electroencephalogram (EEG). This technique is also used for mapping brain activity.
Surgery Conference – Once the patient completes all of the tests, our team meets to discuss the results. Team members include neurologists, neurosurgeons, nurses, neuro-psychologists, psychiatrists, neuro-radiologists, social workers or case managers, and EEG technologists. Together we review all of the information gathered and decide on the best treatment options. We later discuss this information with the patient and their family.
Phase II – After the Phase I evaluation, the care team may determine that more intensive monitoring is needed. The Phase II evaluation uses continuous video-EEG monitoring with intracranial electrodes instead of scalp electrodes to measure seizures. An operation is needed to place special electrodes into or onto the brain in order to perform this evaluation.
Video-EEG monitoring helps us pinpoint the starting point of the seizures within a few millimeter radiuses. This evaluation also helps us to know if the seizures are coming from more than one area of the brain. In addition, we may also perform brain mapping with electrocorticography and stimulation, which can tell us if the seizure focus has any important function such as controlling language, movement, or vision.