43. Non convulsive status epilepticus and EEG

Abstract

Over 50 years ago, EEG revealed nonconvulsive status epilepticus (NCSE). There is no universal agreement on EEG characteristics of NCSE. Lack of consensus arises as NCSE does not exist in isolation, but reflects SE under various conditions occurring with age, cerebral development, encephalopathy, and epilepsy syndrome. Current definitions include “boundary conditions”, with EEG seizure activity without clinical seizures. EEG interpretation is an art; what appears to one as SE, is not to another. Seizures and epilepsy syndromes evolved beyond classification as focal or generalized conditions, into a syndromic approach, with similar evolution of EEG analysis. The NCSE syndromic approach is a clinical and EEG correlation addressing the neonatal period, infancy, childhood, adulthood, and late adulthood based on age, encephalopathy, cerebral development, etiology, and syndrome. Proceeding from a classification of SE, a systematic search for reports with EEG patterns of NCSE using the online medical search engine PubMed for 22 search strategies produced 4328 results, and 123 cases with corresponding EEG patterns of epilepsy syndromes. A synthesis of EEG morphologies and evolutions of individual NCSE syndromes according to the NCSE classification can be found in “Electroencephalographic criteria for nonconvulsive status epilepticus: Synopsis and comprehensive survey” (Sutter and Kaplan, 2012).