Definition

     Recording brain waves using electrodes placed in or on the surface of the brain.

Alternative Names

     Intracranial Monitoring; Depth Electrodes; Subdural Electrodes; Grid Placement; Extraoperative Electrocoritcography

How the test is performed

     If scalp EEG recordings do not localize your seizure, intracranial electrodes may be necessary to acquire further information.

     The epilepsy team will determine the number,the type and the exact placement of electrodes needed to further evaluate the seizure focus.

     The different types of intracranial electrodes include depth electrodes, subdural strips, and subdural grids all of which are placed by the neurosurgeon.

• Depth Electrodes are fine wires placed into the brain tissue.
• Subdural strips are strands of electrodes placed on the surface of your brain via burr holes in the skull. Usually four to eight strips are placed at a given time, covering different brain regions.
• A subdural grid is a rectangular sheet of electrodes placed on the surface of the brain. The grid records seizure activity, and can also be used to map speech and motor areas to help guide the surgeon in the resection.

How to prepare for the test

     You will need to wash your hair the night before the procedure. After washing your hair, do not use any oils, sprays, or conditioner on your hair.

     Part of your head will be shaved. This is done to prevent infection.

     You will be admitted to the hospital at least a day beforethe placement of the intracrainal electrodes.

     You will have had a chance to speak to your neurologist and neurosurgeon before the placement of the electrodes.

     Plan to stay in the hospital for at least 5 to 7 days after the electrodes are placed (longer in case of a grid).

     After the electrodes you will be in a private monitored room such as the onel you were in for video-EEG recordings.

How the test will feel

     You may experience scalp pain and headaches after the procedure. You may also experience some scalp or face swelling, especially with a grid. Your nurses and doctors will do all they can to make you comfortable.

Why the test is performed

     This test is performed to further localize your seizure focus and to map areas of speech and motor function.