Intracranial Monitoring

Reviewed by: HU Medical Review Board | Last reviewed: November 2023 | Last updated: November 2023

If medicine does not control your seizures, your doctor may suggest epilepsy surgery. But before you can have the operation, you may need extensive testing. It will help doctors in figuring out where in your brain seizures begin.

What is intracranial monitoring?

Planning for epilepsy surgery requires a wide range of tests, divided into 2 phases. The first phase includes non-invasive tests like an EEG (electroencephalogram) or MRI (magnetic resonance imaging).1

Sometimes, these tests do not provide enough information for doctors to carry out surgery. This is when they may advise you to move to intracranial monitoring. During this more thorough testing phase, a surgeon will implant electrodes inside your skull.1

Your healthcare team uses imaging guidance to make sure they place the electrodes in the right area. Then they attach the electrodes to brain tissue. After you recover from surgery, you will stay in the hospital. Staff will monitor your brain activity around the clock for days to weeks. You will be able to move around your room and use the bathroom with the help of a portable monitoring device.1

Leading up to the procedure, you will meet with an anesthesiologist, neurologist, and neurosurgical team. You will also have a physical exam. You may have to take extra tests to ensure you are healthy for the procedure, such as blood and urine tests or an electrocardiogram (ECG) to check your heart's electrical activity. Your doctor may also adjust your anti-seizure medicine before the procedure. The entire testing process may take weeks or months.2

How does it help with epilepsy?

Intracranial monitoring helps doctors pinpoint where seizures start in your brain. This type of testing happens pre-surgery and takes into account:2

  • Type of seizures
  • Type of surgery
  • Increasing the benefits of surgery while lowering the risks

Types of intracranial monitoring

There are 3 types of intracranial monitoring:2

  • Stereo-EEG (SEEG) – A surgeon places electrodes deep in your brain. They help doctors figure out exactly where your seizures are happening. Wires attached to the electrodes send electrical activity to a computer. You could wear the electrodes for up to 3 weeks.
  • Subdural strip or grid electrodes – Several EEG electrodes are attached to either a thin plastic strip or a grid. Your surgeon may use both to reach larger areas of the brain.
  • Electrocorticography (ECoG) or intracranial electroencephalography (iEEG) – These procedures map brain functions like speech and memory and find where in your brain seizures begin. This information helps your doctor know how much brain tissue to remove during surgery.

What are the possible risks?

Every surgery comes with potential side effects. With intracranial monitoring, risks include:1

  • Bleeding
  • Infection
  • Brain swelling (edema)
  • Neurological damage

You may be prescribed antibiotics or other medicines to reduce the risk of potential side effects.1,2

These are not all the possible risks of intracranial monitoring. Talk to your doctor about what to expect. You also should call your doctor if you have any changes that concern you about intracranial monitoring.

Things to know about intracranial monitoring

Intracranial monitoring is not necessary for everyone having epilepsy surgery. Your doctor may find a brain lesion is causing your seizures. It does not require as much EEG monitoring before surgery.2

You will likely need intracranial monitoring if it is not clear where in your brain your seizures start. Doctors use imaging, exams, medical history, and non-invasive EEG before moving to surgery.2

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Treatment results and side effects can vary from person to person. This treatment information is not meant to replace professional medical advice. Talk to your doctor about what to expect before starting and while taking any treatment.