Diagnosis -Intracranial Brain Electrode Recording

For patients undergoing epilepsy surgery it is critical that the epilepsy doctor identify the correct area of abnormal brain to be removed. Sometimes enough information can be obtained from routine epilepsy monitoring and other outpatient testing to allow the patient to go directly to surgery. However, in other cases there may be some uncertainty in identifying the abnormal brain area. In most instances the abnormal area can then be identified by placing electrodes on the surface of the brain underneath the skull (subdural electrodes) or within the substance of the brain (depth electrodes). The placement of the electrodes inside the skull is a safe procedure that allows the physician to pinpoint the area of seizure onset. Another reason to use intracranial electrodes are sometimes used is to allow the physician to make sure it is safe to remove the area of abnormal brain before surgery. This is accomplished by putting tiny currents of electricity through the intracranial electrodes to test the function of the underlying brain (e.g., speech, hearing, vision, feeling, etc.) and determine if it can be safely removed.