Mesial temporal subdural electrode as a substitute for depth electrode.

As a substitute for depth electrodes, mesial temporal subdural electrodes were devised. This electrode has a slender trapezoid shape and is easily introduced to the inner uppermost portion of the parahippocampal gyrus. Our results have shown that mesial temporal electrodes can detect not only interictal spikes but also subclinical and clinical seizure discharges from the mesiolimbic structures, and they have excellent capability for lateralization of the mesial temporal epileptic focus. If mesial temporal subdural strips are used in combination with lateral temporal subdural grids, comprehensive understanding of the focus distribution throughout the temporal lobes will be possible without using depth electrodes.