Usefulness of an aura for classification of a first generalized seizure.

In 67 of 149 patients with a generalized first seizure, the occurrence of some kind of sensation immediately preceding the loss of consciousness was the only clue that possibly indicated focal onset of the seizure. We studied the interobserver agreement between six neurologists regarding the interpretation of these preceding feelings as either a nonspecific symptom or an aura implicating a focal onset of the seizure. The observers also classified the seizures as generalized from onset, undetermined, or partial secondarily generalized. To assess the accuracy of the classification, we obtained a standard EEG, an EEG after partial sleep deprivation, a computed tomography (CT) scan, and a follow-up report after 1 year. The subclassification on clinical grounds of a generalized first seizure is too unreliable and probably too invalid as well to be useful in clinical practice or in epidemiologic research.