Does semiology tell us the origin of seizures consisting mainly of an alteration in consciousness?

Abstract

Purpose: Studies on seizures only with an alteration of consciousness were limited mainly to generalized epilepsy. This seizure type has been described rarely in focal epilepsy. We aimed to analyze the semiologic features of this seizure type in focal and generalized epilepsies in a blinded design. Methods: A total of 338 seizure videos in 100 patients were included exclusively by semiologic criteria. Two investigators evaluated the seizure semiology (aura, seizure duration, blinking, mild motor phenomena including automatisms, and so on) from the videos. Primarily the ictal electroencephalography (EEGs) studies and all laboratory findings were evaluated for the localization of the epileptogenic zone and delineating the syndromes, in the second step. Key Findings: Of the focal epilepsy patients (n = 57), the epileptogenic zone could be localized to the temporal (n = 20), frontal (n = 9), and parietooccipital (n = 3) regions. The most common etiology of the generalized epilepsy patients (n = 43) was presumably genetic (n = 33). The presence of aura (none in generalized epilepsy vs. 35% in focal epilepsy; p = 0.0008), lack of blinking (19.3% in focal vs 65.1% in generalized epilepsy; p = 0.01), and longer seizure duration (generalized 14.3 +/- 17.7 s vs focal 54.9 +/- 40.1 s; p < 0.0001) are significantly associated with focal epilepsy, whereas high seizure frequency (p = 0.002), family history of epilepsy (p = 0.016), and responsiveness to therapy (p = 0.004) point to generalized epilepsy with logistic regression analysis. Significance: Seizures consisting mainly of an alteration in consciousness may originate from any brain lobe in focal epilepsies and also occur in generalized epilepsies. Several semiologic and clinical features that help to differentiate between focal and generalized epilepsy should be considered in the syndrome diagnosis.