What is stereoelectroencephalography (SEEG)?

Stereoelectroencephalography (SEEG) is a minimally invasive surgical procedure that is used to identify areas of the brain where epileptic seizures originate. During SEEG, doctors place electrodes in targeted brain areas, which are then monitored to precisely locate the source of the seizure. A SEEG can find seizure sites deep in the brain that a regular electroencephalography (EEG) test may not reach. It covers both sides (hemispheres) of the brain.

When the source of the seizure is found, another brain surgery can be planned to help get seizures under control. This second surgery is usually done four to eight weeks after the SEEG. The ultimate goal of this surgery is to make the patient seizure-free, even with triggers.

Who is a candidate for a SEEG?

If you have generalized epilepsy, SEEG surgery is not an option. SEEG may help if you:

• Have focal epilepsy and seizures (complex partial seizures) that do not respond to two anti-convulsant medications or medical treatment.
• Are a potential candidate for epilepsy surgery.
• If the origin sites of your seizures can’t be found with other tests.

What are the benefits of SEEG?

• SEEG is a minimally invasive approach for epilepsy localization. To implant the electrodes, the surgeon makes 10 to 20 (depending on the patient) small incisions in the scalp and skull, with minimal blood loss.
• While SEEG surgery lasts about four hours and requires general anesthesia, removal of the electrodes is a simple procedure that only takes 10 to 15 minutes under local anesthesia.
• SEEG reaches areas deep in the brain.
• SEEG can be used to monitor both sides of the brain.

What are the risks of a SEEG?

Though SEEG is safe and less invasive it is still brain surgery, which has risks. The main risks are:

• Infection.
• Bleeding.
• Stroke.

What should I expect before undergoing a SEEG procedure?

Here is a general guide (procedure details may vary depending on your healthcare institution) on what you can expect from undergoing a SEEG:

• Before you are admitted into the hospital, expect to have your history taken and a physical to medically clear you for surgery.
• On the day you have your presurgical appointments, you will also have lab work, an EKG, a magnetic resonance imaging (MRI) with contrast and CT (computed tomography) angiography. These imaging tests are done to help in the placement of the electrodes.

What happens during SEEG?

You’ll meet with the anesthesiologist, who will give you a medication to help you sleep. After you’re asleep:

1. A stereotactic frame will be placed on your head.
2. The healthcare team uses all the information from your previous testing as they plan to place electrodes in the part of your brain where they think your seizures are originating. The electrodes are placed through tiny holes that can explore large areas of the brain with minimal tissue damage.
3. Once doctors have placed the electrodes, your head frame is removed. You will be woken up and transported to the recovery area.
4. A postoperative CT scan and skull X-ray will be performed in the recovery room.

What happens after the SEEG is done?

After the procedure you’ll be transferred to an epilepsy monitoring unit. There the electrodes are connected to equipment that records your brain activity.

The length of the monitoring phase varies depending on the frequency of your seizures, but can last a month. After recording has been completed:

• The electrodes are removed under local anesthesia and sedation. Usually this simple procedure takes 10 to 15 minutes in the operating room.
• Your recorded data will be reviewed and epilepsy specialists will form a plan for subsequent treatment of the seizure site, if needed.
• You’ll be discharged with instructions to return in four to eight weeks for the surgery. This “holiday” period will allow for recovery and fewer complications after surgery.

What is the outlook after SEEG?

The kind of epilepsy surgery needed (if any) depends on what the monitoring shows. Your healthcare providers will likely give you preliminary results before you are discharged so that you can be scheduled for further treatment.