[Topographic analysis of interictal spikes in the presurgical evaluation of severe partial epilepsy]

Fifteen patients have been examined: ten suffered from partial epilepsy of presumed mesiotemporal origin (group 1) and the other five presented partial epilepsy with non mesiotemporal or extra temporal epileptic focus (group 2). But in all cases, visual inspection of EEG traces demonstrated focally temporal interictal spikes. We have studied the spike voltage distributions and their corresponding scalp current density fields. Spike voltage topography revealed no significant difference between the two groups. Conversely SCD fields pointed out different specific characteristics according to the group. In the group 1, the gradient was always transversal, between the anterior temporal and the homolateral pre-frontal zones whereas in the group 2 it was antro-posterior in four patients. A more complete analysis of interictal spike by SCD representation should be useful in présurgical evaluation of patients with focal epilepsy.