Staged epilepsy surgery Intracranial EEG monitoring and resection of an epileptogenic zone (1475)

Intracranial EEG Monitoring and Resection of an Epileptogenic Zone

Recent tests show that a specific area of your child’s brain is causing seizures. This area is called a seizure focus.  Sometimes surgery can be done to remove the seizure focus.  The surgery may stop or improve your child’s seizures.  

Before surgery can happen, we need to study the seizure focus. This study is called Intracranial EEG Monitoring with electrodes.  

There are two different types of intracranial electrodes. The type of electrode study recommended for your child depends on where their seizure focus is. One uses depth electrodes and one uses subdural electrodes.

Intracranial EEG monitoring with depth electrodes  

Depth electrodes are thin plastic tubes lined with electrodes that can be placed inside the brain.  They record the brain’s electrical activity. 
These electrodes can be used 
-to study many areas of the brain at the same time.
-to study both sides of the brain at the same time.
-to study areas deep inside the brain.
Before your child’s surgery date, the neurologist and the neurosurgeon will meet to plan placement of the electrodes.

How is the surgery to place depth electrodes done?

• This surgery is done under general anesthesia.
• After your child is asleep, a round frame is placed around their head and kept in place with screws. 
• Next, your child will have a CT scan of the head with this frame in place.
• The pictures from the CT scan guide the exact placement of the depth electrodes.
• Each electrode is placed by making a small incision in the scalp and a small hole in the skull.
• Once the electrodes are all in place, your child will have another CT scan. 
• Your child’s head will then be wrapped with gauze.  It looks much like what is done during long-term monitoring in the Epilepsy Monitoring Unit (EMU). 

Intracranial EEG monitoring with subdural electrodes 

Subdural electrodes are thin plastic strips with electrodes built into them. These electrodes are used if we think a seizure focus is on the surface of the brain or between the two sides of the brain. 

How is the surgery to place subdural electrodes done?  

This surgery is also done under general anesthesia. The neurosurgeon will carefully remove a piece of your child’s skull and put a square grid or rectangle strips on the brain. This is called a craniotomy. 

After the electrodes are placed, the piece of skull is replaced and the skin is closed.

What happens after the intracranial electrodes are placed?  

Your child will recover in the ICU for the first 1 or 2 nights.  Your child will then go to a hospital room in the Epilepsy Monitoring Unit (EMU) to be observed for seizures. Seizures must happen while the electrodes are in place. It is not possible to predict how soon your child will have a seizure. 

These electrodes can also be used for functional brain mapping. This mapping helps to find the areas of your child’s brain that control movement and language. These areas are called eloquent brain. This brain tissue must be left alone to avoid any change in your child’s abilities. Mapping is done in your child’s hospital room after seizures have been captured. The electrodes are still in. 

While the electrodes are in place

• An adult who knows your child and their seizures must be with your child at all times.  This person must:
  – know when you child is having a seizure.
  – tell the nurse when your child is having a seizure. 
• Your child can wear their own clothes as long as shirts or pj tops will button up.
• Your child can talk on the phone, watch TV, read books and play games. 
• Your child can eat and drink. 
• Your child will not be allowed to get out of bed. 
  – Depending on their age, your child might be able to use a commode.
  – A nurse will help your child get on to the commode so that the electrodes don’t get pulled or tugged. 
• A neurologist and a neurosurgeon will talk with you every day during the testing. We will tell you what the doctors are learning from your child’s EEG.  You will help with deciding the next steps of your child’s treatment plan. 

What happens after seizures have happened with the electrodes in place?

The doctors will look at all of the information from the study.  Then they will talk with you about your child’s second surgery. The doctors may: 

1. recommend removal of the seizure focus.   This is called a resection.
2. find that a seizure focus cannot be removed. There are a few reasons this could happen. It can be very disappointing for families.  But the doctors will only recommend removal of a seizure focus if they feel it is safe for your child. 

Depth electrode removal

• After seizures have happened with the electrodes in place, the electrodes are removed.  This is done under anesthesia. Children usually go home from the hospital that same day. 
• If a seizure focus is able to be removed, this is done during a separate surgery, at least three weeks after removal of the electrodes. 
  - This helps lessen the risk of infection. 

Subdural electrode removal:

• If the doctors find that your child’s seizure focus can be removed safely, resection of this brain tissue is done during the same surgery to remove electrodes. 
- This helps lessen the risk of infection. 

Please call the epilepsy surgery coordinator with any questions or concerns you have about the epilepsy surgery process at Children’s Wisconsin.