Within the framework of preparations for surgery of pharmacoresistant epilepsy EEG recording by means of sphenoidal electrodes is an irreplaceable examination method. Its wider use in EEG labora- tories is, however, frequently hampered by inadequate confidence in the asset or exact localization of sphenoidal electrodes as compared with other extracranial electrodes. By comparison of results of semiinvasive EEG with results of examinations with electrodes applied to the scalp and invasive examinations the authors tried therefore to summarize their two-year experience with EEG registra- tion using sphenoidal electrodes. They evaluated retrospectively a group of 35 patients incl. 27 patients with epilepsy of the temporal lobe. They confirmed a significantly higher yield of EEG examinations using sphenoidal electrodes as compared with classical EEG examination. Analysis of interictal records in the group of patients with temporal epilepsy revealed a greater sensitivity of lateralization of a specific focus by 30 %. On evaluation of ictal records the advantage of sphenoidal electrodes in the differentiation of a mesiotemporal onset of ictal activity from a neocortical one was even more marked. The findings were verified by subsequent examination using intracerebral electrodes. Special attention was devoted to the character of ictal EEG patterns in sphenoidal electrodes.

        Key words: sphenoidal electrodes, semiinvasive EEG, SEEG, surgery of epilepsy