Electroencephalography and epilepsy

Objective: To describe the role of die eleciroeneephalograia (EEG) in the evaluation of patients with epifepsy. The EEG is the most,fluently performed neurodiagnostic study in the patient with recurrent unpro- voked seizures ie epilepsy. EEG studies typically record interictal changes in patients with epilepsy because of the paroxysmal nature of the disorder. The mterictal EEG may be useful in the diagnosis of epilepsy and in clessifying seizure type. Ictal EEG recordings are most Commonly obtained in epilepsymonitoring units dutirig long-term EEG studies. The ictal EEG is essential in the preoperative evaluation of patients with intractable patial or localization-related epilepsy in order to localize the epileptogenic zone, ie, the site of seizure onset and initial seizure propagation. Selected patients may require prior chronic intracranial EEG recordings, using depth or subdural electrodes, to determine surgical candidacy. Intracranial EEG monitortrig may be used to identify the epileptogenic zone and to allow delineation of the normal functional cortex that must be spared in a surgical resection.