Most seizures stop. Failure to do so implies that the mechanisms needed to stop seizures are ineffective or treatment simply fails. Defining status epilepticus (SE) clinically is virtually impossible, and many recommendations have included time periods, but the time periods are artificial and not clinically useful. In epidemiologic studies, a definition of ongoing or recurrent seizure without return to baseline level of consciousness for a period of 30 minutes or longer has been us.1 In clinical practice, however, deferring treatment for 30 minutes is unacceptable, and most physicians have adopted an operational definition of seizures persisting beyond 5 to 10 minutes.2 Generally, treatment of convulsive SE should be well on its way before the results of the first electroencephalogram (EEG) become available.
Generalized convulsive status epilepticus (GCSE) is the most common and potentially harmful type of SE. GCSE can evolve from primary generalized or partial seizures with secondary generalization. Convulsive and nonconvulsive SE is the leading indication for emergency EEG and for prolonged video-EEG monitoring (VEM) in the intensive care unit.3–5 Whereas GCSE is diagnosed on clinical grounds, EEG plays a crucial role in determining progression to subtle or nonconvulsive SE, guiding pharmacologic treatment, and in prognostication. The causes, outcome, and management of GCSE in children and adults are quite distinct, and this chapter will focus on adults.
The true frequency of GCSE is somewhat difficult to determine. Case series from tertiary care hospitals are misleading because of selection bias, whereas population-based studies have generally combined GCSE with partial and nonconvulsive SE types. Prospective and retrospective population-based studies from the United States and Europe have estimated an incidence for SE in general of 8.0 to 41.0 cases per 100,000 persons per year.6–12 The incidence is greatest in the first year of life and after the age of 60.6–9,11 GCSE represents 34 to 75% of the SE cases in these reports.6–9 A review of GCSE identified from a California hospital discharge diagnosis database reported an incidence rate of 4.58 per 100,000 for adults ages 20 to 54, increasing to 22.32 per 100,000 for patients older than 75.12 The incidence of SE appears to be greater in men, for reasons that are unclear.6–8,13,14 The impact of race, socioeconomic status, and rural versus urban environment remains uncertain. Most cases (75%) will resolve with treatment in <24 hours.7,9 SE persisting beyond 24 hours is more often seen in elderly patients and in those with acute underlying pathology.7
More than half of all patients with SE have no prior history of epilepsy.6,9,15 This is particularly the case in the elderly. For 70% of those 60 years and older, SE is the initial seizure.6 Among persons of all ...