Phase 3B: Follow-up research using depth EEG
In some cases, we need more information to determine if epilepsy surgery is possible. We must very precisely determine where the focus of the epilepsy is in the brain, to see if a neurosurgeon can remove something from that area without affecting or damaging important brain functions. In phase 3, there are two types of tests. Your doctor will inform you which test applies to you. For these tests, you will be admitted to MUMC+ for surgery. This is special because this surgery is not intended for treatment, but to further establish the diagnosis.
In a stereo EEG (link), we place electrodes deeper into the brain through small holes in the skull. This allows us to better localize the deeper functions in the brain. To properly place the deep electrodes, a frame needs to be firmly attached to the head. This is a painful part of the procedure, but it is necessary to direct the electrodes to the right spot. Even a very small movement causes a deviation in the area of the brain where we need to be. We want to avoid that, of course.
For most patients, the registration and further testing take place at Kempenhaeghe. The day after the surgery, you will be brought there by ambulance. During the registration, we stimulate certain deep brain areas. We do this with small electrical pulses on the electrodes. This temporarily shuts down brain function in that area. This allows us to test whether there are specific brain functions in that area that the neurosurgeon needs to be especially careful with during surgery. Or it becomes clear that surgery is not possible because the risks are too high.
In some exceptional cases, during this test, we can see where the epileptic seizure starts. In such cases, we can try to apply enough electricity to that specific spot to destroy certain proteins in the brain. In this way, the major surgery may no longer be necessary.
Once all tests at Kempenhaeghe are completed, the patient returns to Maastricht. There, the electrodes are removed from the brain. The next day, if everything goes well, you can go home.
Processing all the data from the tests takes 2 to 3 months. At that point, we will know whether surgery is possible.