Foramen Ovale Electrode Recordings

Abstract

The success of surgical treatment of patients suffering from drug-resistant focal epilepsies depends on the precise localization of the epileptic focus. As has been shown already by early attempts of epilepsy surgery, routine scalp-EEG recordings are, as a rule, not sufficient to determine exactly the location of the initiating structure(s) of a seizure event. Therefore, several special extracranial recording techniques were developed in order to overcome this problem. In case of temporal lobe epilepsy this, however, proved to be difficult for several reasons. Firstly, temporal lobe activity, especially in its basal and medial parts, can be recorded only in part even by sphenoidal and nasopharyngeal electrodes. Secondly, temporal lobe seizures often run in parallel with oral automatisms, which result in severe artifacts in recordings from the types of extracranial electrodes mentioned above. In addition, mediobasal temporal lobe epilepsy, the most difficult to record by extracranial electrodes, has proved to be the most common type of temporal lobe epilepsy (Wieser 1983).