System epilepsy: Reply to Lüders et al., 2009

Abstract

To the Editors: In an article recently published in Epilepsia, Lüders et al. (2009) propose a diagrammatic representation of their views on region-specific multifactorial epileptogenicity. In the same article, Lüders et al. comment on the report of a workshop—“Conceptual dichotomies in classifying epilepsies: Partial versus generalized and idiopathic versus symptomatic” (Capovilla et al., 2009)—also published in Epilepsia. In particular, Lüders et al. express their disagreement about the proposed definition of “system epilepsy” by saying that “simply coining a term and talking about system epilepsy will not be necessarily of any help” for understanding the pathophysiologic bases of the classification of epilepsy. I would like to point out that “system epilepsy” is not proposed as a mere linguistic expression but as a concept to designate those types of epilepsy in which seizures are accounted for by discharges involving a specific system, defined according to anatomic and physiologic criteria. The concept implies a specific susceptibility of the involved system as a whole, although within that system some trigger areas may be identified. Examples are childhood absence epilepsy (CAE) and benign epilepsy with centrotemporal spikes (BECTS). These epilepsy syndromes are presently classified into two separate categories (generalized and partial epilepsies, respectively), although many epileptologists agree that BECTS shares more characteristics with CAE than with other focal epilepsies due to known external causative factors. Quite interestingly, recent information from experimental studies suggests that bilateral synchronous spike–wave discharges of CAE actually have a localized origin within the involved thalamocortical circuitry at the somatosensory cortex (Meeren et al., 2002; Polack et al., 2007). Until further evidence clarifies this matter, everyone is obviously free to keep his/her own view. Personally, however, I believe that the concept of “system epilepsy” could generate more productive testable hypotheses than the waving diagrams proposed by Lüders et al. (2009). I confirm that I have read the Journal’s position on issues involved in ethical publication and affirm that this letter is consistent with those guidelines. I have no conflicts of interest to disclose.