Background
Localization of the source of brain activity using an electroencephalograph (EEG) enables non-invasive visualization of the generators of epilepsy in an anatomical 3‑D space. Initially the localization of interictal epileptic discharges with high-density EEG (hdEEG) was established, before techniques are also now being looked for, in order to localize ictal events.
Objective
This article summarizes the current state of the literature on localization of interictal discharges and gives an overview of the current questions.
Material and methods
The most important articles on various parameters, such as documentation of the discharge, marking the time point, role of head models and number of electrodes are discussed and the most important studies with patient cohorts are presented.
Results
In several studies with large patient cohorts, the localization of the source of interictal epileptic discharges was successfully proven with hdEEG. When this is combined with a head model based on the magnetic resonance imaging (MRI) of the patient, a high sensitivity (84%) and specificity (88%) can be achieved, which is superior to the other imaging techniques, such as MRI, PET and SPECT.
Conclusion
The EEG source localization of interictal epileptic discharges is precise and powerful. In view of the clinical relevance EEG source localization should be an established component in the presurgical clarification of patients with drug-refractory epilepsy, in addition to the other widely used imaging techniques.