Response – Focal seizures and consciousness


In the first proposal for an international classification of epileptic seizures (Gastaut et al., 1964) elementary (later replaced by simple) versus complex partial seizures were introduced as the two major classes of partial (now focal) seizures, but without unequivocal definitions. The international seizure classification of 1981 (Commission on Classification and Terminology of the ILAE, 1981)) which was for the first time based upon an analysis of video recorded seizures established retention versus impairment of consciousness as the distinguishing feature because impaired consciousness was the only symptom common to all seizures the experts had rated as complex partial. This definition was not met by unanimous agreement. Two major arguments against were that the concept of consciousness was elusive and in praxis difficult to separate from awareness and responsiveness, and that the state of consciousness during a seizure, though of great practical consequence, did not reflect a pathophysiological difference fundamental enough for a major dichotomy. Especially the latter point was emphasized when the ILAE Classification Task Force in 2001 recommended abandoning the term (Engel, 2001).

Whereas Alvarez-Rodriguez et al. add to the conceptual discussion of consciousness focusing on the aspect of self-awareness during a seizure, Blumenfeld & Jackson propose that in the light of newer research the Engel, 2001 reasoning was wrong and there are enough differences in anatomical involvement to justify using impairment of consciousness to dichotomize. However, the data they discuss seem to be mostly related to seizure spread which is not different from the 1981 classification. Primary differences of seizure generation or differences of the ictogenic networks at rest would make a much stronger case for a dichotomy. Such differences may well be established in the future but we are not yet there. Thus, the discussion emphasizes once more that our nosological understanding of the epilepsies is in transition and undergoing rapid changes.

Generalizations are always problematic. If it were true, as Alavarez-Rodriguez et al. state, that auras always produce absolute passiveness, the entire therapeutic field of self-control, e.g. by seizure arrest (Wolf, 2002) or by acute drug application (Wolf, 2011) would not exist, and the indispensible cooperation of patients in identifying an operable epileptogenic focus were impossible. Also, this commentator who has always been fascinated by auras, discussing their details with hundreds of patients cannot confirm their “invariable” suddenness. Especially in experiential auras it is often impossible for patients to define where the normal flow of thoughts and memories ends and the aura experience begins. During antiepileptic drug therapy, as aura symptoms dwindle patients may become aware of more subtle perceptions preceding what they were used to consider their first aura symptoms. These perceptions have none of the qualities described here. Patients tend not to pay any attention to them. Isolated auras may for many years be the only seizure type, perceived as a mere curiosity. But the type of aura experiences the authors discuss does exist and it is meritorious that they draw attention to epileptic impairments of consciousness that are qualitative rather than quantitative producing a narrowing of the field of consciousness. It is thought-provoking that they have to go back to Kinnier Wilson, Karl Jaspers and Henri Ey to find these discussed. Of the features they mention only the strangeness of the experience seems to have been studied in recent years (Schwabe et al., 2009). More research into these aspects is certainly desirable.


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