This chapter describes the diagnosis, types, and management of nonconvulsive status epilepticus using a case-based approach. Generalized status epilepticus including nonconvulsive status epilepticus (NCSE) is a medical emergency that is best managed in an intensive care unit with continuous EEG monitoring. Refractory status epilepticus (RSE) is defined as the failure of seizure activity to terminate despite initial benzodiazepines and additional intravenous antiseizure medications. Refractory status epilepticus is an indication for intravenous anesthetics such as midazolam and propofol with the goal of titrating to burst suppression. Highly epileptiform bursts seen are associated with status epilepticus recurrence despite treatment with intravenous anesthetics, a condition known as super-refractory status epilepticus (SRSE). Additionally, this chapter also describes how to recognize status epilepticus cessation and an uncommon form of NCSE called absence status epilepticus.

The electroencephalogram (EEG) is created by differential amplification of cortical postsynaptic excitatory and inhibitory potentials. As a neurophysiologic monitor, it can be used as a bedside tool to assess an unresponsive patient in an emergency setting, particularly in the case of a patient with a history of epilepsy or an unexplained coma. Use of EEG in the emergency department (ED) can be technically challenging; both obtaining and interpreting the study may pose difficulty in small community hospitals or remote settings.

SE is defined as 5 minutes or longer of continuous clinical and/or electrographic seizure activity or recurrent seizures without interval recovery; t1 refers to the time point beyond which there is failure of mechanisms responsible for seizure termination or initiation of mechanisms which lead to abnormally prolonged seizures, and t2 refers to the time point beyond which there are long term consequences due to neuronal injury, death, and alteration of neuronal networks. Semiologically, SE can be classified as with or without prominent motor features. Convulsive SE may evolve into NCSE in a significant minority after convulsive activity ceases. NCSE may be diagnosed on EEG in a significant minority of critically ill patients. EPC may not be associated with ictal activity on surface EEG. De novo absence SE may be seen in older individuals in the setting of abrupt benzodiazepine withdrawal. They may have a previous or family history of IGE.