The importance of semiological information based on epileptic seizure history

Semiology is the backbone of any correct categorization of seizures, as epileptic or not, focal or bilateral, and is fundamental to elucidating how they are anatomically generated in the brain. An anatomical hypothesis derived from seizure history is the precondition for optimally designed ancillary studies. Without understanding seizure semiology, no rational therapy is possible. This article describes the semiological approach using patient history based on full use of patients' self-reports as well as descriptions by witnesses. Auras represent the subjective aspects of seizures and provide important semiological clues as observable signs, sometimes including rather precise direct anatomical information. Methods of extracting, facilitating and analysing self-reports including linguistic conversation analysis are presented in detail. It is highlighted that prodromes, seizure triggers and reflex epileptic mechanisms can provide crucial information for diagnostics and therapy. Special issues considering seizure semiology in children are discussed in a separate section. Other sections are dedicated to the two most important issues of differential diagnosis: how to distinguish (1) focal from "generalized" epilepsies, particularly when focal seizure phenomena appear in a bilateral epilepsy; and (2) epileptic from a series of non-epileptic events.