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Spatial Distribution of Neuronal Complexity Loss in Neocortical Lesional Epilepsies
Author(s) -
Widman G.,
Lehnertz K.,
Urbach H.,
Elger C. E.
Publication year - 2000
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1157.2000.tb00247.x
Subject(s) - ictal , neocortex , temporal lobe , epilepsy surgery , epilepsy , neuroscience , stereoelectroencephalography , psychology , medicine
Summary:Purpose : Nonlinear EEG analysis is valuable in characterizing the spatiotemporal dynamics of the epilepto‐genic process in mesial temporal lobe epilepsy. We examined the ability of the measure neuronal complexity loss ( L *) to characterize the primary epileptogenic area of neocortical lesional epilepsies during the interictal state. Methods : Spatial distribution of L * ( L * map) was extracted from electrocorticograms (n = 52) recorded during presurgical assessment via subdural 64‐contact grid electrodes covering lesions in either frontal, parietal, or temporal neocortex in 15 patients. The exact location of recording contacts on the brain surface was identified by matching a postimplant lateral x‐ray of the skull with a postoperatively obtained sagittal MRI scan. Reprojecting L * maps onto the subject's brain surface allowed us to compare the spatial distribution of L * with the resection range of the extended lesionectomy. Results : In each of the six patients who became seizure‐free, maximum values of L * were restricted to recording sites coinciding with the area of resection. In contrast, L * maps of most patients who had no benefit from the resection indicated a more widespread extent or the existence of additional, probably autonomous, foci. The mean of L * values obtained from recording sites outside the area of resection correctly distinguished 13 patients (86.7 %) with respect to seizure outcome. Conclusions : Relevant information obtained from long‐lasting interictal electrocorticographic recordings can be compressed to a single L * map that contributes to a spatial characterization of the primary epileptogenic area. In neocortical lesional epilepsies, L * allows for identification and characterization of epileptogenic activity and thus provides an additional diagnostic tool for presurgical assessment.