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Epilepsy Program: Monitoring seizures

At the UCI Health Comprehensive Epilepsy Program, your doctors will have you undergo comprehensive testing prior to surgery using implanted — or intracranial — electrodes.

We offer subdural electrode monitoring (SGDE) and stereo-encephalography (SEEG) monitoring. While standard EEG and other noninvasive tests, such as MRI or PET scans, can indicate which side of the brain a seizure is coming from, intracranial monitoring helps pinpoint the exact part of the brain producing the seizures.

Intracranial monitoring is also used by surgeons to map the brain and to help them avoid sensitive areas of the brain that control functions, such as movement and speech, during surgery.

Your intracranial test plan is developed for your specific needs by our team, which includes neurologists, neurosurgeons, neuroradiologists and other specialists. They will select one of the two types of pre-surgical intracranial testing.

Subdural electrode grid testing

Some patients undergo subdural grid monitoring. This test consists of placing a group of tiny electrodes mounted in thin plastic on the surface of the brain to record electrical activity.

The electrodes are sometimes arranged in a square grid formation or in straight lines called strips.

While the patient is under anesthesia, the surgeon makes small burr holes in the skull, or sometimes a larger a larger opening, which is called a craniotomy. This is done to allow the insertion of the grid or strips under the skull.

The electrodes are typically placed under the temporal or frontal lobes of the brain.

After surgery, the patient is moved to the epilepsy monitoring unit, where seizure activity is recorded over days or weeks. After the monitoring period is complete, the electrodes are removed.

Subdural electrode grid testing is typically used to determine the specific part of the brain that is responsible for producing seizures, as well as to help map the locations of critical brain functions, such as speech, in relation to the part of the brain causing the seizure.

Subdural grid testing may be a good choice for patients whose seizures are thought to originate on the surface of the brain, but it may be less effective for seizures that originate deep in the brain.

Stereo-encephalography (SEEG)

This type of intracranial monitoring also involves placing electrodes in the brain to locate the origins of seizure activity.

Surgeons place a stereotactic frame on your head and conduct imaging tests, such as MRI or CT, to identify where they will place the electrodes.

The patient is then placed under anesthesia and the surgeon makes a dozen or more burr holes in the skull and inserts tiny electrodes into the brain with a wire.

After surgery, the patient is taken to the epilepsy monitoring unit, where the electrodes are connected to devices that record seizure activity for a period of days or weeks. After the monitoring is complete, the electrodes are removed in a short procedure.

As a minimally invasive procedure, SEEG is being is recommended more frequently today based on studies showing the technique's success in identifying the part of the brain triggering seizures in a majority of patients.

Studies indicate that SEEG may be useful to identify deep areas of the brain producing seizures that can’t be identified using subdural electrode grid testing. This type of testing is useful when doctors need to examine both sides of the brain. The risks of SEEG include a small chance of infection or hemorrhage.

Expert, team-based care

Intracranial seizure monitoring is only performed at centers equipped with the necessary expertise and facilities.

At the UCI Health Comprehensive Epilepsy Program, we evaluate more patients than any other program in the region. We are designated as a Level 4 — the highest level possible — comprehensive epilepsy center by the National Association of Epilepsy Centers.

Our six-bed epilepsy monitoring unit offers both subdural grid and SEEG monitoring, which means we are able to use the most appropriate form of monitoring for each individual patient.

Contact us

For more information or to make an appointment, call 714-456-6203 or request an appointment online.

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