The evolving classification of seizures and epilepsies

Authors


  • Controversial Issues
    The following commentaries on the Shorvon and Berg/Scheffer articles in this issue, and the responses from Shorvon and Berg/Scheffer, were invited by the Editors-in-Chief

Berg and Scheffer (2011) advocate a new classification of the epilepsies, and propose to highlight causes that may be identified with modern investigatory methods—principally genetics, imaging, and metabolic. They recognize that the classification is fluid and will be living, adapting to new developments and understanding. The recognition that epileptic seizures may arise in a malfunctioning network is to be welcomed, as is the acceptance that not all epilepsies maybe conveniently pigeon-holed into focal or generalized categories. The “structural/metabolic” classification is indeed a bit of a ragbag and needs to be appreciated as such. Some of these epilepsies—for example, associated with tuberous sclerosis or inherited metabolic disorders—will have a genetic cause. Furthermore, the genetic basis of many of these conditions is yet to be elucidated. The “unknown cause” classification has the attraction of being what it says on the box, and without any subtext meaning—actual or intended.

In terms of seizure classification, I am not enthusiastic about giving up the terms “simple partial” and “complex partial,” which are straightforward and clear. Certainly, the features of the seizures and their likely localization and lateralization should be described. But I do not find the term “focal seizures with dyscognitive features” intuitively superior to “complex partial.”

It will certainly be useful, as Shorvon (2011) suggests, to build a catalog of causes of the epilepsies, and to recognize that this listing will expand, that parts may wither as more knowledge unfolds, and that there will be genotypic and phenotypic heterogeneity. I am not convinced, however, of the utility of the concept of provoked epilepsy, and suggest that the concept of provocation be confined to seizures.

Precision of use of language is critical if a classification system is to be useful and widely adopted. It is regrettable that many authors, including the authors of the articles under discussion, make inappropriate usage of the term “etiology” as a synonym for “cause.”“Etiology” is the study of causation, not a cause in its own right—any more than physiology and psychology are specific processes.

Disclosure

I have received Institutional support from UCB Pharma, Eisai, GSK, Janssen-Cilag, Cyberonics, MedTronic, and GE Healthcare. I confirm that I have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

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