Resection surgery for partial epilepsy. Relation of surgical outcome with some aspects of the epileptogenic process and surgical approach

Abstract

In spite of the progressive improvement of the results of resective surgery for epilepsy, the number of not significantly benefited patients remains high. An attempt was made to find out a relation between outcome and some aspects of the pathophysiological organization of the epileptogenic process and of the surgical procedure. Chi-square and logistic regression statistic analyses were utilized. The study was retrospectively performed on 138 surgically treated patients having a minimum follow-up of three years. Three classes of surgical outcome were considered: completely seizure free (including aura; 86 cases, 62.3%), significant seizure reduction (31 cases, 22.5%), and no significant improvement (21 cases, 15.2%). What follows was brought into evidence by the study. 1) On the diagnostic side, the spatial arrangement (focal, unilateral, multifocal) of both the interictal and the ictal epileptic electrocerebral activities are significantly associated with the surgical outcome. Their relative impact on outcome is related to the presence of a structural lesion: when a lesion is documented, the interictal activity has the higher value: vice versa, when no lesion is apparent, the role of the ictal activity is prevalent. However, the presence, as well as the nature of the lesion, per se, are not significantly associated with outcome. 2) On the surgical side, the extent of resection of both the structural lesion and of the epileptogenic zone are highly associated with the surgical result; the extent of lesion resection prevails on that of the epileptogenic zone. The type of surgical approach (hemispherectomy: 17 cases; temporal lobectomy: 67 cases; extratemporal resection: 54 cases) has no significant relation to the outcome. The value and the limits of the results obtained are discussed.