Advances in EEG: home video telemetry, high frequency oscillations and electrical source imaging.

Over the last two decades, technological advances in electroencephalography (EEG) have allowed us to extend its clinical utility for the evaluation of patients with epilepsy. This article reviews three main areas in which substantial advances have been made in the diagnosis and pre-surgical planning of patients with epilepsy. Firstly, the development of small portable video-EEG systems have allowed some patients to record their attacks at home, thereby improving diagnosis, with consequent substantial healthcare and economic implications. Secondly, in specialist centres carrying out epilepsy surgery, there has been considerable interest in whether bursts of very high frequency EEG activity can help to determine the regions of the brain likely to be generating the seizures. Identification of these discharges, initially only recorded from intracranial electrodes, may thus allow better surgical planning and improve surgical outcomes. Finally we discuss the contribution of electrical source imaging in the pre-surgical evaluation of patients with focal epilepsy, and its prospects for the future.