Diagnostic EEG

Video-EEG monitoring allows your doctor to see exactly how many seizures you’re having and where your seizures begin. If you undergo continuous monitoring, you’ll be admitted to the hospital for observation.

EEG (electroencephalogram) electrodes are placed on your head or sometimes inserted into your cheek. They’ll stay in place for three to seven days. The electrodes are connected to EEG monitoring equipment and a video camera records you the whole time. Doctors compare the video to the electrical activity recorded by the EEG to get a better understanding of your seizures. You’ll be able to move around in your room but you won’t be able to leave it.

During monitoring, your anti-seizure medicine will be reduced, and we may also use sleep deprivation to induce seizures.

If you haven’t already, you may also have an MRI and PET scan during your stay, along with a SPECT scan and other tests.

Your Hospital Stay for EEG Monitoring

We encourage you to wear your regular clothes, but please avoid anything you have to pull on over your head. You’re invited to bring plenty of reading material and your favorite hobbies to help pass the time. The team will take a look at any personal items for safety reasons.

After the Diagnosis

If you’re here for diagnosis, you’ll go home with a plan for a follow-up visit.

If you’re here for surgical evaluation, you’ll be discharged once the level of medicine in your blood returns to normal. The epilepsy team will review all the findings and decide on the next stage of testing. If we can identify the location of your seizures, you’ll be invited in for a Wada test (see below). If not, we may admit you later for evaluation with intracranial electrodes.

Intracranial Electrodes

Intracranial electrodes are fine wires placed inside the brain to record electrical activity. The electrodes may be single-depth electrodes, subdural strips with six to eight contact points that lie on the surface of the brain, or subdural grids of up to 64 contact points that help doctors map speech and movement areas.

The electrodes will be surgically inserted and will be removed once we have enough information about where your seizures begin.

Placing Intracranial Electrodes

The surgery typically lasts between four to six hours and you will be able to get out of bed within 24 to 48 hours. You may have some side effects, including a headache and some scalp or eyelid swelling. Some patients may experience a leak of clear spinal fluid, which is completely harmless.

EEG Recording With Intracranial Electrodes

We start recording 24 to 48 hours after the electrodes are inserted. You can expect to stay in hospital for about 10 days, depending on the number of seizures you have. To ensure we can monitor your seizures, your medication will be reduced, and we may use sleep deprivation, just as with your initial evaluation.

You might be asked to read or carry out tasks to help us map out important areas of your brain.

Going Home After Evaluation

Once the level of medication in your blood is back to normal, you’ll be able to go home. Most patients return to work or school after a few days. Meanwhile, the team will review the findings and decide whether epilepsy surgery is a good option for you.

Wada Test

You must tell your doctor if you are allergic to iodine or shellfish before taking this test.

For the Wada test, we inject dye through a catheter in your groin. The dye travels to your head and allows us to see the blood vessels in your brain. Once the dye is in place, we’ll connect you to an EEG machine and use medicine to put half of your brain to sleep. We’ll ask you some questions and to remember some words or pictures. We’ll then repeat the test on the other side.

After the test, you’ll need to lie in bed with your leg up for six to eight hours to prevent bleeding from the catheter site.