After your initial evaluation at the Epilepsy Center, your doctor may order various tests to locate the exact cause of your seizures and determine the best treatment for you. Testing usually happens in three phases.
Phase 1: Preliminary tests
This testing is done to more clearly define your epilepsy. It is also used in preparation for surgery.
You will usually stay in the hospital for five to seven days. During that time
- You will be admitted to a private room in the Neuroscience unit of the hospital.
- We will obtain a detailed seizure history and determine your medication levels.
- Non-invasive gold discs will be placed on your scalp to record the electrical activity of your brain during an electroencephalogram (EEG).
- You may have neuropsychological tests (see below) to help find the affected area of your brain.
- A psychiatrist may see you to help determine how epilepsy affects your quality of life.
- You may be taken off your anticonvulsant medication to promote seizures. Three or more seizures are recorded on video and EEG. Before you leave, you will go back on medication. If all appropriate medications fail, your doctor will consider surgery.
- If you do not have at least one seizure after a week, you may be discharged and readmitted later.
- In some cases, you may be able to take portable EEG equipment home with you for a period of time.
Neuropsychological testing is often helpful in locating the part of the brain that may be causing seizures.
These pen-and-paper tests measure motor skills, language abilities, and memory, and can take four to six hours to complete. They can be done in one day or over several days.
Phase 2: Wada test
If phase 1 testing indicates that surgery may help you, the team will use the Wada test (developed by neurologist Juhn Wada in the 1940s) to evaluate whether you are a good candidate for surgery. This test is also used in preparation for surgery.
The test is the only known way to examine how a specific side of the brain works. It does this by:
- Determining the memory and language functions in each side of your brain
- Mapping how each side of your brain works
- Tracing the arteries that supply blood to each side of your brain
The Wada test involves injecting a short-acting sedative through a catheter in the carotid artery. This puts one half of the brain "to sleep" for up to five minutes while the other side of the brain continues to function as usual. This allows the neurologist and neuropsychologist to test each side of the brain separately for speech and memory.
Before the Wada test, you will have an angiogram, which takes X-ray pictures of the arteries that supply blood to your brain.
Ictal SPECT scan
If necessary, you will have an ictal SPECT (single photon emission computed tomography) scan following the Wada test. Ictal means relating to seizures. The SPECT scan helps your doctor find out where the seizures are beginning.
Often those with epilepsy have seizures because certain areas of the brain experience changes in blood flow. During this test, your doctor will inject a radioisotope into your vein during a seizure, and then you will have a SPECT scan to measure blood flow to the brain. The procedure will be repeated when you are not having a seizure so your doctor can compare the two scans.
This test requires being admitted for video/EEG monitoring. It is unlikely that you would stay in the hospital longer than five days. The length of stay depends largely on how frequently your seizures occur. Your medication may be reduced before you are admitted to encourage seizure activity.
Phase 3: Electrode placement
If the epilepsy team determines that you need more detailed testing, they will recommend electrode placement to better determine where in the brain the seizures are happening. This testing involves surgically placing electrodes into and over your brain.
Because this is a surgical procedure, you will have the following tests several days beforehand:
Your medications may be decreased or discontinued prior to electrode placement.
During the test, the neurosurgeon will place special electrodes on the surface of your brain or deep within the brain, or both, depending on your particular type of epilepsy. Seizures are recorded as they occur.
Your doctor will determine which of two types of tests you will take:
- Type 1: Your surgeon will implant electrodes into your brain. During the procedure, you will be awake but given sedation and local anesthesia. These electrodes can be removed at your bedside, so you do not need additional surgery to remove them. You will undergo video/EEG monitoring and be observed closely by our nursing staff. You will stay between five and ten days or until your doctor gathers enough information.
- Type II: Your doctor will implant a "grid" of electrodes over the surface of your brain while you are under general anesthesia. Grid electrodes allow for greater coverage over the surface of your brain. Your doctor must remove a small portion of bone to place the electrodes. This bone is replaced after the video/EEG monitoring when you go back to the operating room. Usually, you will have the electrodes in place for a week while your doctor gathers the necessary information. Then you will have surgery to remove the abnormal brain tissue.
If you need surgery in particular areas of the brain, you will have a functional mapping test to show where vital functions in the brain such as speech, motor function (the ability to move your arms, leg, and face), and sensory function (such as tingling feelings) originate.
During this testing phase, you are restricted to bed to ensure your safety during the monitoring process. At times, light cloth restraints may be necessary to protect you from injury during a seizure.