Evolving Concepts of Nonconvulsive Status Epilepticus

Abstract

Nonconvulsive status epilepticus (NCSE) may have existed as long as humans have, but it was probably conceptualized first about two centuries ago. Only after Berger’s development of the EEG in the mid twentieth century, however, were the classic syndromes of absence and complex partial (focal) NCSE described conclusively. Nevertheless, there were also “borderline” conditions such as atypical absence status and electrical status epilepticus in sleep, in which it was unclear how much the epileptiform discharges contributed to alterations of consciousness or behavior. More recently, with expanding use of continuous EEG monitoring in ICUs, most diagnosed NCSE is of a very “non-classic” type, occurring in patients with concomitant medical, neurologic, and traumatic illnesses contributing to and confounding the diagnosis of NCSE. Currently, various forms of periodic discharges are the most common borderline states. The complexity of concomitant illnesses makes it very difficult to define NCSE precisely in these non-classic cases—which also defy classification. These complexities also make it hard to determine the likely consequences of most forms of NCSE and to plan for the best treatment of so many varieties of NCSE. Nevertheless, the knowledge of NCSE is expanding rapidly, and better understanding seems likely to lead to better treatment decisions.