Stereoelectroencephalography, also called stereo-EEG or sEEG, is a minimally invasive procedure. It uses electrodes placed directly in the brain to identify where epileptic seizures start.

For patients with difficult-to-treat seizures, epilepsy monitoring with sEEG before epilepsy surgery can help pinpoint the precise source of the seizure activity. Surgeons can then remove the part of the brain that is causing the seizures.

sEEG is one tool your child's team in the CHOP Neuroscience Center can use to help achieve the best seizure control while minimizing risk and discomfort and maximizing your child's quality of life. This advanced diagnostic procedure requires state-of-the-art equipment and technology. An experienced neurosurgeon and clinical team with expertise diagnosing and monitoring children with epilepsy should perform the procedure.

Before sEEG was available, this type of epilepsy monitoring required a craniotomy. The neurosurgeon removed a portion of the skull to expose the brain, and then placed strips or grids onto the brain. sEEG is much less invasive.

How does sEEG work?

• sEEG will happen in an operating room, with the patient under general anesthesia.
• Neurosurgeons place thin wires called electrodes directly into the brain. These electrodes can reach areas of the brain that aren't accessible through other techniques.
• Electrodes record the electrical activity in the brain during a seizure.
• Brain activity is closely monitored to find patterns and locate the origin of the seizure.
• Once the source of the seizure is identified, surgeons may be able to remove (resect) that section of the brain with the goal of eliminating seizures or reducing the number and severity of seizures.

Advantages of stereo-EEG

• sEEG is minimally invasive - Doctors can implant electrodes into the brain without having to remove the skull, unlike older techniques such as craniotomy. This leads to fewer complications, less post-operative pain, and a shorter length of stay in the hospital.
• sEEG allows for precise, targeted treatment - With stereo-EEG, neurosurgeons and epilepsy specialists can more precisely identify where seizures originate and safely reach areas of the brain that can't be reached with grids and strips.
• Surgical planning is improved with stereo-EEG - sEEG helps to identify areas of the brain that must be preserved, including those responsible for language, motor and sensory function. 

In some cases, a surgical robot may be used to help place the electrodes. The primary benefit of robotic-assisted stereotactic EEG is that it can significantly reduce the length of the surgery.

What to expect during sEEG

If your child has been determined to be a good candidate for epilepsy surgery, they will first have a thorough evaluation with the team in CHOP's Neuroscience Center.

If your child is scheduled for stereo-EEG monitoring, they will be admitted to the Children's Hospital of Philadelphia. An expert pediatric anesthesiologist will administer general anesthesia to make sure your child is comfortable and safe throughout the procedure.

Steps in the sEEG procedure:

• A stereotactic frame is placed on the head.
• Using the information collected from MRI and CT scans, doctors determine where they think seizures are occurring, and use this to guide placement of electrodes.
• Tiny openings are drilled in the skull. The small electrode wires are inserted through these openings, and electrodes are placed directly into the brain in the areas where it appears seizures are originating.
• After the electrodes are placed, the head frame is removed and your child proceeds to the recovery room.
• In our state-of-the-art Epilepsy Monitoring Unit, electrodes are connected to equipment that monitors brain activity. Your child will have continuous video-EEG monitoring for anywhere from a few days to a few weeks while seizure activity is monitored.
• Epilepsy specialists, including neurologists, neuroradiologists and neurosurgeons, will carefully review these data to determine if the area of the brain causing the seizures can be safely resected (surgically removed).
• After sEEG monitoring is complete, your child will continue to the next step in their treatment plan. This could include minimally invasive surgery, vagal nerve stimulation or medical management.