Traditionally, status epilepticus (SE) was defined as continuous or repetitive seizure activity persisting for at least 30 minutes without recovery of consciousness between attacks. More recently, authors have suggested that seizures exceeding 5 to 10 minutes should be considered SE.1,2 For all practical purposes, a patient should be considered to be in SE if a seizure persists for >5 minutes, as very few single seizures last this long.3
This chapter will focus on patients with status epilepticus that does not respond to initial therapy, known as refractory status epilepticus (RSE). RSE can be defined loosely as failure of any of the standard regimens for SE.4 The exact definition of RSE is controversial. Major points of controversy are the number of antiepileptic drugs (AEDs) required to have failed (usually two or three) with or without a requirement for a certain amount of time to have passed. We use the following definition, as do many others: RSE is convulsive or nonconvulsive SE that continues clinically or electrographically despite first- and second-line therapy,4 with no minimum amount of time required.
Patients with RSE primarily have clinically subtle electrographic or nonconvulsive seizures. Another term for nonconvulsive status epilepticus (NCSE) is subtle status epilepticus, defined as consisting of “nystagmus, eye blinking, and/or mild motor movements with marked impairment of consciousness and continuous or nearly continuous, usually bilateral, ictal patterns on the EEG [electroencephalogram].”5 The same authors later described a continuum of SE from convulsive to subtle to only electrographic,6 a common scenario in RSE. Although subtle status epilepticus has been applied broadly to any SE with subtle clinical manifestations, the 2006 International League Against Epilepsy proposed classification uses the term for the more specific scenario described by Treiman,5,6 in which convulsive SE is followed by periodic epileptiform discharges with subtle or no clinical manifestations.7,8 We have suggested the following term (after Latin consultation) and definition for this phenomenon.8
Status epilepticus terminans: A condition after an overt convulsive seizure in which the patient is comatose for at least 30 minutes and has periodic epileptiform discharges on EEG and subtle or no clinical correlate other than coma. The preceding convulsive seizure can be of any duration, and the periodic discharges can be lateralized or generalized.
Prior to the widespread use of EEG monitoring, the incidence of RSE was estimated at 2000 to 6000 cases per year in the United States.9 Exact incidence and prevalence numbers are difficult to obtain in the absence of a population-based study conducting continuous EEG monitoring for all patients with status epilepticus. The results of the Veterans Affairs (VA) Cooperative study,10 a randomized trial that compared four different first-line interventions for generalized convulsive status epilepticus (GCSE), indicated that RSE may be ...