Terminology

Underlying cause: Current terms used for identifying broad classes of cause and mode of presentation will likely to be revised in the future.  The terms idiopathic (presumed genetic and largely benign), symptomatic (secondary to another condition, often a structural lesion), and cryptogenic (presumed symptomatic in the 1989 Classification document) are still in use but increasingly problematic.  All epilepsy is symptomatic of something, and often many different influences, some as yet unidentified, may play a role.  Not all genetic epilepsies are benign either from the perspective of seizure control or in terms of accompanying psychiatric and cognitive co-morbidities.  Not all symptomatic epilepsies are “malignant.”  The substitution of outcome for nature of cause is a serious error that should be addressed.  As for cryptogenic, many genetic epilepsies have been identified from among the “presumed symptomatic” epilepsies (e.g. Dravet, GEFS+, ADNFLE, ADPEAF) suggesting that the presumption is not justified and cryptogenic would perhaps be better construed as “unknown.”  Specific plans for replacing these terms have not been finalized; however, the intention is to have terms that accurately reflect our understanding of the nature of the cause on the basis of the best available evidence.  Of note, a deterministic understanding of causation in epilepsy is something we have not yet achieved at this time.  Any classification of cause or origin will reflect our understanding of the central, essential causal factors and not the entire cascade of causation, at least for now.

Mode of presentation or ictogenesis and spread: The terms focal and generalized suggest a simple dichotomy but belie a more diverse range of phenomena. No specific proposals have been developed to replace these terms, which are deeply entrenched in our vocabulary and in our thinking about seizures, epilepsy, and treatment. The Commission is considering how best to acknowledge and distinguish epilepsy and seizures secondary to an anatomically demonstrable lesion versus epilepsy and seizures that occurs in association with a functional disruption. Multifocal, hemispheric, and diffuse are other variants that may need to be more explicitly acknowledged. The bilaterally symmetric, centrally generated rhythm of the IGEs is aptly described as generalized even if some asymmetries or frankly focal findings can occasionally be demonstrated. GEFS+ or epilepsy secondary to a GLUT1 deficiency, West syndrome and many other forms of epilepsy are generalized, but not in the same sense. The use of these terms in reference to specific seizure types versus electroclinical syndromes will likely require some further consideration. How best to capture these distinctions in our terminology remains unresolved.