Management of Status Epilepticus in Adults

Non-convulsive SE (NCSE) is defined as the presence of altered consciousness or behavior for ≥ 30 minutes, the absence of overt clinical signs of convulsive activity during that period, and the electroencephalographic (EEG) confirmation of seizures or activity that responds to treatment together with improvement of consciousness [12–15]. Two major types of NCSE can be encountered: the one in patients with epileptic encephalopathy/coma and the one in patients with absence or complex partial seizures, who are not usually admitted to ICU and are functional yet impaired. Because of the confusion between these 2 extremes in the NCSE spectrum, working criteria for standardization of reporting, utilizing the frequency of electroencephalographic epileptiform discharges or delta/theta waveforms have been proposed [15]. A recent compendium of 123 cases of NCSE with clinical descriptions and EEG patterns following a syndromic classification approach has also been published [16].

Types of SE

Three major categories of SE have been described: generalized convulsive SE (GCSE), focal motor SE (FMSE or epilepsia partialis continua [EPC]) of Kojevnikov, and NCSE. GCSE and FMSE are easily recognized due to overt convulsions. NCSE, however, has a more obscure phenotype and can be subdivided into a spectrum encompassing typical absence and complex partial SE, atypical absence SE and tonic SE (usually in children with learning disabilities), epileptic behavioral disturbance and psychosis, including Balint–like syndrome [17], confusional states or delirium with epileptiform discharges) and SE in coma (after significant brain injuries, such as hypoxia-ischemia, most commonly encountered in ICUs) [13,18]. The 2 extremes in this NCSE spectrum have completely different prognoses, with absence SE the most benign and SE in coma the most dismal.

Lastly, SE presents either spontaneously or can be “semi-intentional” iatrogenic, encountered either in the neuro-ICU or epilepsy monitoring unit, when AEDs are withdrawn under continuous EEG recording in order for seizures to emerge and be recorded with surface or intracranial electrodes.

Incidence of SE

In a prospective population-based epidemiological study, the incidence of SE was estimated at 41–61/100,000 patients/year. For the US, this translates to 125,000 to 195,000 episodes per year [19].

The highest incidence of SE occurs during the first year of life and during the decades beyond 60 years, and is also dependent on the SE subtype. Partial SE occurs in 25% of cases of SE and NCSE accounts for another 4% to 26 % [19,20], but the incidence for the latter is considered an underestimate due to the need for continuous EEG monitoring (which is not widely available). For example, NCSE was discovered in no patient with acute stroke [21], 8% of comatose ICU patients [22], 7% of patients with intracerebral hemorrhage [23], 3% to 8% of patients with subarachnoid hemorrhage [24–26], 6% of patients with metastatic cancer [27], and 6% of patients with head trauma [28].

The incidence of RSE and SRSE is also unknown. In a recent retrospective study from a neuro-ICU in a West China hospital, the percentage of non-refractory SE, RSE, and SRSE were 67.3%, 20.4% and 12.2%, respectively [29]. Other retrospective studies have shown that 12% to 43% of SE cases become refractory [30–33] and that approximately 10% to 15% of all cases of hospital-admitted SE will become super-refractory at some point, but no prospective studies have been published.