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Intracranial Monitoring

Editorial Team's avatar image

By Editorial Team

3 min read

Reviewed by: HU Medical Review Board | Last reviewed: December 2024 | Last updated: March 2025

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 – electrodes can be placed on the surface of the brain or deep in the 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

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Before the procedure, you may need to adjust your medicines as directed by your care team. You will meet with an anesthesiologist. 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 the health of your heart. The entire testing process may take weeks or months.2

During the procedure, you will be asleep under anesthesia. Your surgical team will access the brain by creating openings in the skull. The openings can be very small or large depending on the requirements of the procedure. For some procedures, you may recover in a neurologic intensive care unit (NICU) and then transfer to an epilepsy monitoring unit (EMU) where you will have additional monitoring.

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 2 main types of intracranial monitoring:2

  • Depth electrodes  – This procedure is minimally invasive and is performed when seizures are thought to originate deep in the brain. A surgeon places electrodes deep in your brain through small holes drilled in the skull. Wires connect the electrodes to a monitoring device which can identify areas of the brain where seizures originate and also important areas of the brain that must be preserved during surgical planning (for example areas important for language).
  • Subdural electrodes – This procedure is performed when seizures are thought to originate near the surface of the brain. Electrodes are attached to the surface of the brain, specifically underneath the brain’s membrane cover called the dura. This procedure typically requires a large opening in the skull called a craniotomy.

What are the possible risks?

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

  • Bleeding
  • Infection
  • Brain swelling (edema)
  • Headache
  • Damaged brain tissue

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 clear 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

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.