Do you or someone you know have a condition called epilepsy that is difficult to control despite medication? Sometimes doctors have a hard time pinpointing where in the brain the seizure is starting. That's when we're going to talk about a slightly complicated but very important test that can help. It's called SEEG. Don't worry, the name may sound a bit long. Let's keep it simple.
What does SEEG simply mean?
Simply put, Stereoelectroencephalography (SEEG) is a surgical test that goes deep into your brain and uses tiny incisions to pinpoint where intractable epileptic seizures (fits) begin.
You've probably heard of an EEG test. It involves placing small electrodes on the top of the head, that is, on the skull, to measure the electrical activity of the brain. But in SEEG, neurosurgeons insert these electrodes not on the surface of the brain, but deep and diverse areas of the brain. This allows information to be obtained from areas that are too deep for a regular EEG to capture.
After the electrodes are inserted, you will be kept in a special unit of the hospital for a few days. During this time, a medical team will closely monitor your brain activity during your seizures.
The main purpose of this test is to determine whether the brain cells causing the fits can be surgically removed, and if so, exactly where to remove them.
In what cases is the SEEG test performed?
Doctors use SEEG testing mainly for a few special cases.
- Drug-resistant epilepsy: Some people cannot control their seizures even after using two or three types of medication. We call this drug-resistant epilepsy. In children over 2 years of age and adults with this condition, SEEG is very important to determine if surgery is possible.
- Brain mapping: Imagine that the seizure is coming from a critical part of the brain that controls speech, movement, or sensation. If you are going to have surgery, you need to be careful not to damage those critical parts. Using SEEG electrodes, you can map these critical areas precisely before surgery.
- Guide other treatments: Sometimes SEEG testing is also used as part of a treatment. For example:
- Radiofrequency thermocoagulation: This uses radio waves and heat to destroy the brain cells that are causing the seizure. This treatment can be done using SEEG electrodes.
- Thermoablation (LITT): A method that uses laser heat energy to deactivate the parts of the brain that are causing the seizure.
- Responsive neurostimulation: In this, a device is implanted in the brain that delivers a small electrical stimulus to the point where the seizure begins and then stops it. SEEG helps to find the exact location of the device.
Who is eligible for this test?
The SEEG test is not for everyone. Your doctor will consider several factors before recommending it.
Imagine you have a seizure that starts in a specific area of your brain (`(focal epilepsy)`). But even with an MRI scan, that area is not clearly visible. That's when SEEG becomes most useful.
However, if you have a seizure that starts in many areas of the brain at once (`(generalized epilepsy)`), you are not suitable for this test.
| Possible situations for SEEG testing | |
|---|---|
| Status | Description |
| If you are a candidate for epilepsy surgery | If you think surgery can cure the condition, this test may be necessary before it happens. |
| A fit that is not controlled by medication | If the fit cannot be controlled despite trying two or more medications. |
| If not clear from other tests | When tests like MRI and EEG cannot give a clear picture of where the fit begins. |
What are the main differences between EEG and SEEG?
Although both of these tests measure the electrical activity of the brain, there are big differences. Typically, a doctor will first perform an EEG. Only if the information obtained from that is not enough will they proceed to a second-stage test, such as a SEEG.
The main changes are:
- Where the electrodes are placed: In EEG, the electrodes are placed on the skin surface, above the skull. In SEEG, the electrodes are inserted deep into the brain.
- Information received: EEG only provides information about the surface activity of the brain. SEEG can obtain information at different depths in both hemispheres of the brain. This allows us to pinpoint the exact location of the seizure.
One study found that people who underwent epilepsy surgery after a SEEG scan spent less time in the operating room than those who underwent other methods (such as opening the skull and placing electrodes on the surface of the brain). They also spent less time in the hospital and used less pain medication.
What to expect before SEEG?
Since this is a test related to surgery, several tests will be performed to check your health status beforehand.
- Blood tests
- An EKG (Electrocardiogram) test that checks the heartbeat
- Imaging tests such as CT scans (computed tomography scans) and MRI scans (magnetic resonance imaging)
One of the fears that many people, especially parents, have when doing something like this to their child is , "Will they cut off all their hair?" There may also be questions about whether they will have to stop taking the medication they are taking for the fit for a while.
Be sure to discuss any concerns or fears you may have with your medical team before your surgery. They will do their best to keep you as stress-free and relaxed as possible.
How is SEEG surgery performed?
SEEG surgery usually takes about four to six hours. On the day of surgery, the anesthesiologist will give you medication. You will be completely asleep throughout the procedure. So you won't feel any pain.
After you are asleep, the surgical team will follow these steps:
1. First, a special frame (`(stereotactic frame)`) is attached to your head to keep your head in one place.
2. Next, about 10 to 20 very small holes, about the width of a strand of spaghetti, are drilled in the skull. These do not cause much bleeding.
3. Through those small holes, flexible plastic-like electrodes connected to thin wires are inserted into the brain.
4. These electrodes are precisely placed in the areas of the brain where the seizure is suspected to be starting, as identified in previous scans.
5. Finally, the head frame is removed and the head is tightly bandaged.
6. You will then be taken to the recovery room and a CT scan and X-ray will be taken to make sure the electrodes are in the right places.
What happens after SEEG?
After surgery, you will usually be transferred to an Epilepsy Monitoring Unit. There, a team of specialists will monitor you 24/7. Electrodes on your head will be connected to machines that record your brain activity. When you have a seizure, a computer can show you where it starts in your brain and how it spreads, using 3D images.
You may need to stay in the hospital for a few days to a week or two, depending on how often you have the fit.
At the end of the test period, the electrodes will be removed from your head. Don't worry, this isn't a major operation. It's just a simple procedure that numbs those areas and takes about 10-15 minutes.
Are there any risks to the SEEG test?
SEEG is generally considered a very safe procedure, but as with any brain surgery, there are very small risks.
- Bleeding inside the brain (intracranial hemorrhage)
- Infection
- Stroke
But remember, these are very rare events. The medical team takes every precaution to minimize these risks.
How long does it take to heal?
You should usually be back to normal within a day or two (24-48 hours). However, talk to your medical team about when you can resume your normal activities.
What can you expect from SEEG results?
In many cases, a SEEG test can successfully pinpoint the underlying cause of the seizure. Doctors will then carefully study the data recorded from your brain activity and decide whether you are eligible for surgery or other treatment.
Surgery to treat epilepsy usually takes place four to eight weeks after the SEEG test, to give you time to recover properly.
You may receive preliminary test results before you leave the hospital. This will give you and your family time to discuss these results with the medical team and make a decision before a final treatment plan is decided.
Living with a seizure that can't be stopped with medication can be very challenging. But with modern testing methods like SEEG, it's now possible to pinpoint the exact cause of the seizure and start the appropriate treatment. These treatments can help you reduce your seizures and live a normal life.
Take-Home Message
- SEEG is a specialized test for epileptic seizures (fits) that are difficult to control with medication.
- What is done here is to insert electrodes deep into the brain through small holes and find the exact point where the fit begins.
- Based on the results of this test, doctors will decide whether surgery or other treatment is right for you.
- Although this is generally a very safe procedure, as with any surgery, there are some minor risks.
- Always talk openly with your doctor about any questions or concerns you have.
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